JV-ODE Physics Thread 8

Now available for Blitz3D & BlitzMax (Win32)

The JV-ODE Physics Wrapper is an advanced user library supporting almost all of the Open Dynamics Engine functions wrapped inside a DLL (Dynamic Link Library).

The library can be used with any programming language that supports DLL's, including Blitz3D and BlitzMax (Win32). The Euler rotation system in JV-ODE has been adapted to match the left-handed Euler rotation used in Blitz3D, however functions for accessing Quaternion and Axis Angle rotation systems are also included. The full versions contain all of the necessary files to get you started, including over 30 demos showing the various features found in ODE and a complete Function Reference document.

The BlitzMax (Win32) version also features a built-in 'bare-bones' OpenGL 3D engine module and B3D mesh loader module for demo purposes.

To view more information and screenshots click here.

Options are now available to purchase the wrapper using either PayPal or Share*it.

The Blitz3D restricted demo version is now available for download here (211KB)

The BlitzMax (Win32) restricted demo version is now available for download here (290KB)

Have Fun :)

Previous JV-ODE Threads: 1 2 3 4 5 6 7
JV-ODE Player Factory Forum

Useful Links: ODE.org Website - ODE Wiki - ODE User Guide (PDF) - ODE User Guide (HTML)

Thanks for the reply in the old post... I suppose it could be nice to have some sort of FAQ file or something in your own website. Blitzforums are bit difficult place to deal with your customer support ;) It's quite difficult to find the answers by searching (and believe me - I'm trying to do that!) - so we end up asking you over and over.

Rightio, me again... :)

According to the official docs, when a collision occurs a temporary 'contact joint' is created (for the duration of the step).

Is this contact joint (and it's data) accesible through jv-ode?!?

If so, it could possible help me obtain accurate information of the forces involved when two rigid bodies collide - ie. if I then would be able to get some Feedback on that joint?!

thanks,
Danny.

Yes it is Dan,
Luckly for us back in JV-ODE v1.11 Vip3r added support for joint feedback back. Check out the Car Demo joint feedback.

The update included:

Added new joint feedback functions...

dJointFeedbackEnable(joint)
dJointFeedbackDisable(joint)
dJointFeedbackIsEnabled(joint)
dJointSetFeedback(joint,feedback)
dJointGetFeedbackForce1(joint)
dJointGetFeedbackTorque1(joint)
dJointGetFeedbackForce2(joint)
dJointGetFeedbackTorque2(joint)

Added new demos...

Demo-RagDolls (Update)
Demo-RagDolls-Zombie
CarDemo-JointFeedback

@Game Producer: You're welcome :) - It would be very difficult and time consuming to create an all encompassing JV-ODE FAQ, anyway I don't mind being asked over and over.

@Danny: The contact joint is used internally in JV-ODE and is supplied with data, it doesn't return any data. Collision depth provides values which you can interpret easily and are directly related to the force of the impact.

@Wayne, thanks mate. I'm familiar with the jointfeedback functions, but I was hoping to get feedback on the contact joints created when rigid bodies collide... But that won't be possible..

@Vip3r, ok you sold me dude! When I did first tests the collision Depth would give me weird and useless off-the-scale values. But I found out if you do NOT set any global 'dContactXXX' settings when initialising the simulator, it DOES give you values VERY close to what the collision FORCE should be!!! Especially when you multiply the collision Depth values by twice the mass of the rigid bodies. Check this examples where you will notice 'some' but very acceptable inaccuracies between Depth vs Force calculations:

; ###################################################################################################

AppTitle "JV-ODE - COLLISION FORCE / DEPTH / MASS test"

Include "JV-ODE.bb"

Graphics3D 800,600,0,2

Type ODEGeom
	Field body
	Field geom
	Field mesh
End Type

; ###################################################################################################

; ### Setup ODE

Global World=dWorldCreate()
Global Space=dHashSpaceCreate(0)
Global ContactGroup=dJointGroupCreate(0)

dWorldSetAutoDisableFlag(World,1)
dWorldSetGravity(World,0,-0.98,0)
;dContactSetMode(dContactBounce)		; Do NOT enable these!! It will cause the Collision Depth values
;dContactSetBounce(0.1)					; to go nuts and off the scale !!!!!
;dContactSetMu(48)


	RedWeight# = 1.0
	BlueWeight# = 10.0


; ### Create RED Test object

	ode.ODEGeom=New ODEGeom
	ode\body=dBodyCreate(World)
	dBodySetRotation(ode\body,0,0,0)
	dBodySetPosition(ode\body,-30,90,0)
	dBodySetAutoDisableFlag(ode\body,1)
	ode\geom=dCreateSphere(Space,4)
	dGeomSetBody(ode\geom,ode\body)
	ode\mesh=CreateSphere()
	ScaleMesh ode\mesh,4,4,4
	RotateMesh ode\mesh,0,0,0
	PositionMesh ode\mesh,0,0,0
	EntityColor ode\mesh,255,0,0

	RedBody = ode\body
	RedGeom = ode\geom

	;create RED mass
	mass = dMassCreate()
	dMassSetSphereTotal mass, RedWeight, 4
	dBodySetMass ode\body, mass

; ### Create BLUE Test object
	
	ode.ODEGeom=New ODEGeom
	ode\body=dBodyCreate(World)
	dBodySetRotation(ode\body,0,0,0)
	dBodySetPosition(ode\body,30,90,0)
	dBodySetAutoDisableFlag(ode\body,1)
	ode\geom=dCreateSphere(Space,4)
	dGeomSetBody(ode\geom,ode\body)
	ode\mesh=CreateSphere()
	ScaleMesh ode\mesh,4,4,4
	RotateMesh ode\mesh,0,0,0
	PositionMesh ode\mesh,0,0,0
	EntityColor ode\mesh,0,150,255

	BlueBody = ode\body
	BlueGeom = ode\geom
	
	;set BLUE mass
	mass = dMassCreate()
	dMassSetSphereTotal mass, BlueWeight, 4
	dBodySetMass ode\body, mass

; ### Create light
Global Light=CreateLight()
RotateEntity Light,45,-90,0
LightColor Light,255,255,255
AmbientLight 130,130,130

; ### Create camera
Global Camera=CreateCamera()
CameraClsColor Camera,0,0,0
CameraRange Camera,1,1000
PositionEntity Camera,0,90,-100
RotateEntity Camera,30,0,0

; ### Create plane
dCreatePlane(Space,0,1,0,0)
Plane=CreatePlane()
PlaneTexture=CreateTexture(128,128,9)
ClsColor 0,200,80
Cls
Color 255,255,255
Rect 0,0,64,64,1
Rect 64,64,64,64,1
CopyRect 0,0,128,128,0,0,BackBuffer(),TextureBuffer(PlaneTexture)
ScaleTexture PlaneTexture,80,80
EntityTexture Plane,PlaneTexture,0,0

CreateMirror()

Color 255,0,0
; ###################################################################################################

While Not KeyHit(1)

	PTime=MilliSecs()

	UpdateGeoms()

	dSpaceCollide(Space,World,ContactGroup)
	dWorldQuickStep(World,0.1)
	dJointGroupEmpty(ContactGroup)

	PhysicsTime#=MilliSecs()-PTime

	UpdateWorld
	RenderWorld

	Color 255,255,0
	Text 0,0,"JV-ODE Version "+dGetVersion()
	Text 0,15,"Physics Time:"+PhysicsTime

	HaveHit = False

	;get RED's vertical velocity
	If dGeom1CountCollisions(RedGeom)>0 Then
		dBodyGetLinearVel(redBody)
		nx# = dVectorX#()
		ny# = dVectorY#()
		nz# = dVectorZ#()
		rVel# = Sqr( nx*nx + ny*ny + nz*nz )
		rForce# = rVel# * RedWeight# ; F=M*A
		rPen# = dGeom1CollisionDepth(redGeom,1)
		HaveHit = True
	EndIf
	
	;get BLUE's vertical velocity
	If dGeom1CountCollisions(BlueGeom)>0 Then
		dBodyGetLinearVel(blueBody)
		nx# = dVectorX#()
		ny# = dVectorY#()
		nz# = dVectorZ#()
		bvel# = Sqr( nx*nx + ny*ny + nz*nz )
		bForce# = bVel# * BlueWeight ; F=M*A
		bPen# = dGeom1CollisionDepth(blueGeom,1)
		HaveHit = True
	EndIf
	
	If HaveHit Then
		HaveHit = False
		;multiply collision depth by MASS to get some sort of difference
		;then scale it up to get some more 'workable' value
		rPen# = ( RedWeight#*2) * rPen#
		bPen# = (BlueWeight#*2) * bPen#
		
		Text 0,50, "RED  BODY (1  kg!): velocity = "+rVel#+"  collision Force = "+rForce#+"  collision DEPTH ="+rPen#
		Text 0,65, "BLUE BODY (25 kg!): velocity = "+bVel#+"  collision Force = "+bForce#+"  collision DEPTH ="+bPen#
		
		Color 0,0,0
		Text GraphicsWidth()/2,GraphicsHeight()/2,"< PRESS ANY KEY - for next collision's info..>",1,1
		Flip
		WaitKey()
	EndIf
	Flip
Wend

dJointGroupDestroy(ContactGroup)
dSpaceDestroy(Space)
dWorldDestroy(World)
dCloseODE()

End

; ###################################################################################################

Function UpdateGeoms()

	For ode.ODEGeom=Each ODEGeom
		If dBodyIsEnabled(ode\body)
			RotateEntity ode\mesh,dGeomGetPitch#(ode\geom),dGeomGetYaw#(ode\geom),dGeomGetRoll#(ode\geom)
			PositionEntity ode\mesh,dGeomGetPositionX#(ode\geom),dGeomGetPositionY#(ode\geom),dGeomGetPositionZ#(ode\geom)
		End If
	Next
	
End Function

sweet! :)

You're getting there :)

However, you should be able to use 'Penetration*Mass' as a guide to the impact force and ignore the velocity stuff completely.

The reason for the odd results when used with the contact settings (which you will need to use), is the bounce value. Try it with the contact settings enabled but with '0.0' bounce. With bounce enabled, the objects will gradually penetrate further into another object before moving away from it, hence your wild values.

To return all collision depth data, you will need to cycle through all of the collisions using the index parameter. The spheres in your example will only register one contact each, but if you changed them for cubes you will notice each cube registers approx three contacts.

You will also need to use the dGeom2CollisionDepth() function to return the collision depth data for collisions with smaller objects.

Yep, got all that covered in my engine now with relatively little tweaking..
Work pretty good and 1000 times faster than using those cursed Sqr's ;)

Thanks for your troubles,
Danny

Stop!

I've thought of another way to get an indication of impact forces and it works perfectly using Joint Feedback, much better than collision depth. I'd even go as far as saying much better than using Joint Feedback on contact joints themselves.

But... while testing this idea, I've noticed that the Joint Feedback feature in JV-ODE isn't working correctly when multiple joints are feedback enabled.

The good news is it will be fixed and released very soon. I'll include a Collision Force demo showing the above idea too.

SHTOPPED! :)

You've made me very curious!
Guess it's a bit early for a drum roll? :)

Danny
p.s. Use the Force dude!

JV-ODE V1.18 Update Released

Please check your inbox :)

The new update corrects an issue found in the Joint Feedback feature of JV-ODE.

Please let me know if you experience any problems with the new update.

:)

@Danny: Here's the Collision Forces demo to work with JV-ODE V1.18

; ###################################################################################################
; #								   JV-ODE - Collision Forces Demo									#
; #									Code by Jim Williams (VIP3R)									#
; #								Devious Codeworks - Copyright © 2006								#
; ###################################################################################################

AppTitle "JV-ODE - Collision Forces Demo"

Include "JV-ODE.bb"

Graphics3D 800,600,0,2

Type ODEGeom
	Field body
	Field geom
	Field mesh
End Type

Dim Force(10)
Dim Joint(10)

; ###################################################################################################

; ### Setup ODE

Global World=dWorldCreate()
Global Space=dHashSpaceCreate(0)
Global ContactGroup=dJointGroupCreate(0)

dWorldSetAutoDisableFlag(World,1)
dWorldSetGravity(World,0,-0.98,0)
dContactSetMode(dContactBounce)
dContactSetBounce(0.95)
dContactSetMu(48)

; ### Create light

Global Light=CreateLight()

RotateEntity Light,45,-90,0
LightColor Light,255,255,255
AmbientLight 130,130,130

; ### Create camera

Global Camera=CreateCamera()
CameraClsColor Camera,0,0,0
CameraRange Camera,1,1000
PositionEntity Camera,0,40,-30
RotateEntity Camera,30,0,0

; ### Create plane

dCreatePlane(Space,0,1,0,0)

Plane=CreatePlane()

EntityAlpha Plane,0.5

PlaneTexture=CreateTexture(128,128,9)

ClsColor 0,200,80
Cls

Color 255,255,255

Rect 0,0,64,64,1
Rect 64,64,64,64,1

CopyRect 0,0,128,128,0,0,BackBuffer(),TextureBuffer(PlaneTexture)
ScaleTexture PlaneTexture,20,20
EntityTexture Plane,PlaneTexture,0,0

Mirror=CreateMirror()

AddObjects()

; ###################################################################################################

While Not KeyHit(1)

	PTime=MilliSecs()

	UpdateGeoms()

	dSpaceCollide(Space,World,ContactGroup)
	dWorldQuickStep(World,0.1)
	dJointGroupEmpty(ContactGroup)

	PhysicsTime#=MilliSecs()-PTime

	UpdateWorld

	RenderWorld

	Text 0,0,"JV-ODE Version "+dGetVersion()
	Text 0,15,"Physics Time:"+PhysicsTime

	Text 10,280,"Collision Force:"

	For count=1 To 10
		dJointGetFeedbackForce1(Joint(count))
		ShowBar(78+(count*58),320,dVectorY())
	Next

	Flip

Wend

dJointGroupDestroy(ContactGroup)
dSpaceDestroy(Space)
dWorldDestroy(World)
dCloseODE()

End

; ###################################################################################################

Function AddObjects()

For count=1 To 10
	; ### Body + Geom
	ode.ODEGeom=New ODEGeom
	ode\body=dBodyCreate(World)
	ParentBody=ode\body
	dBodySetRotation(ode\body,0,0,0)
	dBodySetPosition(ode\body,-55+(10*count),45,30)
	mass=dMassCreate()
	dMassSetSphereTotal(mass,0.5,4)
	dBodySetMass(ode\body,mass)
	dMassDestroy(mass)
	dBodySetAutoDisableFlag(ode\body,0)
	ode\geom=dCreateSphere(Space,4)
	dGeomContactSetMode(ode\geom,dContactBounce)
	dGeomContactSetBounce(ode\geom,count*0.1)
	dGeomSetBody(ode\geom,ode\body)
	ode\mesh=CreateSphere()
	ScaleMesh ode\mesh,4,4,4
	EntityColor ode\mesh,Rand(255),Rand(255),Rand(255)
	EntityAlpha ode\mesh,1
	EntityShininess ode\mesh,0.7

	; ### Core Body
	ode.ODEGeom=New ODEGeom
	ode\body=dBodyCreate(World)
	CoreBody=ode\body
	dBodySetRotation(ode\body,0,0,0)
	dBodySetPosition(ode\body,-55+(10*count),45,30)
	mass=dMassCreate()
	dMassSetSphereTotal(mass,0.5,4)
	dBodySetMass(ode\body,mass)
	dMassDestroy(mass)
	dBodySetAutoDisableFlag(ode\body,0)

	; ### Join Core + Parent
	Joint(count)=dJointCreateFixed(World,0)
	dJointAttach(Joint(count),CoreBody,ParentBody)
	dJointFeedbackEnable(Joint(count))
Next

End Function

; ###################################################################################################

Function ShowBar(xpos,ypos,yvec,size=8)

If yvec<0
	Color 240,0,140
	Else
	Color 0,240,140
	End If

Rect xpos,ypos,size,size+Abs(Int(yvec*2))

Color 255,255,255

End Function

; ###################################################################################################

Function UpdateGeoms()

For ode.ODEGeom=Each ODEGeom
	If ode\geom
		If dBodyIsEnabled(ode\body)
			RotateEntity ode\mesh,dGeomGetPitch#(ode\geom),dGeomGetYaw#(ode\geom),dGeomGetRoll#(ode\geom)
			PositionEntity ode\mesh,dGeomGetPositionX#(ode\geom),dGeomGetPositionY#(ode\geom),dGeomGetPositionZ#(ode\geom)
			End If
		End If
Next

End Function

; ###################################################################################################

You will notice in the AddObjects() function I've created an extra ODE body (with no geom), it is then connected to the parent ODE body using a fixed joint. To read the force and torque, you can call Joint Feedback on these fixed joints. The benefit to this method over Joint Feedback directly on contact joints is that you only need to deal with one value, rather than one value per contact (up to 4+ contacts per body). Let me know if it works well for you ;)

!!!super duper cool viper!!!

I'm gonna dive it to it right away... I'm especially curious to see if the joint feedback takes the body's mass into account as well...

thanks dude!!
d.

oooookay.... What about this then?!

If you print the forces in numbers by replacing this for..next in the main loop:

For count=1 To 10
	dJointGetFeedbackForce1(Joint(count))
	ShowBar(78+(count*58),320,dVectorY())
	Text 0,100 + (count*15), "Force = "+dVectorY#()
Next

Then you'll see that ALL bodies give EXACTLY the same numbers! AT THE SAME TIME! My feeling is that ALL 'dJointGetFeedBackForce' calls return only the value of the FIRST joint ?!?!
You'll see that the numbers stop changing as soon as the first ball comes to a rest - whilst the other, more bouncy ones on the right are still hapilly going up 'n down!

Might this be because of the double-rigid-fixed-joint technique you're using... or perhaps something wrong with the forcefeedback internals???

Danny
p.s. If you set all the body mass' to 1.0 in stead of 0.5 - you'll see that the eventual force when the bodies are at rest, is 0.98 ie. gravity! that's pretty cool!

Er... Danny you must still be using V1.17, the problem you've described is the exact issue that has been fixed in V1.18 ;)

Update your JV-ODE.dll

DOH!

Thanks for the update,Viper.
I have a question:
I create a sphere in the camera position to simulate I am throwing a grenade in the direction the camera is pointing, and then apply a force. I use dbodysetrotation (ode\body,entitypitch(camera),entityyaw(camera),entityroll(camera)) ,( I don´t remember the correct syntax,sorry) , but it doesn´t work and the sphere-grenade is always 0,0,0 rotated, and the force is applied in the same direction (pointing 0,0,0).
How can I create and rotate the sphere-grenade to match the direction the camera is facing?
Thanks.

I've always wondered about the car demos included in this package. The car always seems to act a bit strange for me, it's difficult to describe. I've never really played a car simulation that behaves like this one does, and I guess it just bothers me. It seems very "jerky", at times it seems like the car becomes almost weightless and flips over on its back as if it were made of cardboard.
Is this the way these demos are intended to behave? I just can't imagine someone wanting to use a car that behaves this way in a game so perhaps I'm missing something.
Great work on the library otherwise though, its nice to see this thing being continually updated.

@angel martinez: It sounds like you're always applying the force in the same direction (not relative to the current rotation). It's difficult to help without some code showing your problem, there could be several factors involved. If you still can't get it to work, post (or email) an example so that I can help you.

@chaduke: Thanks :) The car demo isn't intended to be a realistic car simulation, but to show new users how the 'hinge2' joints are used to create a wheeled vehicle. If a real car was made from four spheres and an evenly weighted rectangle, would that handle a bit strange? Almost definitely :)

Creating an accurate car simulation is very complex and thus unsuitable to use as demos for new users. You would have to create the car body using several ODE bodies, each with the correct mass etc. The weight in a real car is distributed, for example there's more mass near the engine. You also need to apply force and torque to the wheels properly, simulating the transmission etc, something which often gets overlooked. You then need to setup the contact surfaces correctly for both the tyres and ground surface, plus tweak the suspension. All of the above will affect the way the car will handle in the real world and it's the same in ODE. The more complex the simulation, the closer to reality it will be, but that's way beyond the purpose of the demos ;)

The code is like:

rx#=entityPitch(camera)
ry#=entityYaw(camera)
rz#=entityRoll(camera)
x#=entityX(camera)
y#=entityY(camera)
z#=entityZ(camera)

if keyhit(34) ; ////////////////////////
ode.ODEGeom=New ODEGeom
ode\body=dBodyCreate(World)
dBodySetRotation(ode\body,rx#,ry#,rz#)
dBodySetPosition(ode\body,x#,y#,z#)
dBodySetAutoDisableFlag(ode\body,1)
ode\geom=dCreateSphere(Space,1)
dGeomSetBody(ode\geom,ode\body)
ode\mesh=CreateSphere()
ScaleMesh ode\mesh,.5,.5,.5
EntityAlpha ode\mesh,1
EntityShininess ode\mesh,0.7

dBodyAddForce ode\body,0,0,50
end if ; /////////////////////////////

The sphere is throwed always in the direction 0,0,0 and not in the camera direction.

You're always applying the force in the same direction (z axis), not relative to the current rotation of the camera.

To add force relative to the camera body you should use...

dBodyAddRelForce(ode\body,0,0,50)

:)

Thanks for the reply VIP3R, that explains a lot. Has anyone coded a more realistic car simulation using your library in Blitz3d yet? If so I'd love to look at it. If not, perhaps its a project I can work on, possibly porting someone elses code from C++.

No problem :)

Well, I've seen a few good car sims (mostly work in progress) but there are probably lots of projects using JV-ODE that I've not seen yet. The best JV-ODE car simulation I've seen so far has to be Tricky Tracks.

There are quite a few ODE car projects listed here. Porting C++ ODE stuff should be painless too as most functions in JV-ODE use the original API names and parameters.

I've started work on a JV-ODE car editor. You can load cars/wheel meshes into the garage, tweak your ODE settings with sliders, test your settings by cruising around a bit and tweak them even while driving... you can even lift the car and drop it to test the suspension. In the end you have the option to export your settings.

Anyway, I'm looking for ideas from you all as to what features you'd like to see.

I'm not in the car business myself but I'm guessing it would be cool if the editor can simply export the settings and build the car in the form of blitz code. Or in the form of some 'data file' with load/save_car() functions.

If you then supply some basic support functions (accelerate car, steer left/right, dunno) then I think a lot of people would be very greatfull to you :) ?!

http://static.4players.de/premium/Screenshots/2d/8a/98321-vollbild.jpg




just kidding :)


say a word, if you need any help! e.g. i've got a highly improved version of blitzui over here, if you need a decent gui...

Is that Live for Speed? Sweet game.

Free this wrapper!!!

We want it for free!!! :D

J/K

I have a question: (very noobish I know)
How can I test wether 2 geoms are colliding?
And can I test with how much force they are colliding?

I used the spheresample "BouncyWorld" and changed it a little. I changed the "Addobject"-function and made:

Function AddObject()
  ;Create Body Geom and Mesh
  Return ode\geom
End function

Now I want to do this:

global Testball=Addobject()

For ode.odegeom=each odegeom
   If Objectscollides(Testball,ode\geom)
      ode\damage=ode\damage+Getcolforce()
  endif
next

Good question FreeTimeCoder..

Just scroll up and the answer is there, I just asked the same question recently :)
You might also wat to check the posts at the end of the previous thread #7..

hope it helps and you figure it out, if not let me know..

d.

@FreetimeCoder: You can get full collision feedback. Check the 'CarDemo-CCount' and 'CarDemo-DetailedC' demos included with the wrapper. Also check the JV-ODE Function Reference under 'Unique JV-ODE Functions>Collision Functions' for more info. Note these features are not included in the demo version of JV-ODE.

For the second question, yes as Danny says we've just been working on getting some collision force feedback. There's a new demo a few posts up ^ to show the feature. Again this feature will only work with the full version of JV-ODE.

XD Sorry I haven't seen this.
Great it works!
But i have 1.16 ?
I have to check my E-mails again..

It was sent to the email address you registered during the purchase, which is different to the one in your profile.

Let me know if you didn't get it, or if you need your email address updating ;)

Got it!
When I purchased it i haven't got an email adress..
It is registered on my fathers adress. Will be nice, if you change it.

Forcedetection works GREAT!

No problem, I've updated it for you.

:)

Can you show how to create a static collision trimesh from a vertex and indice array? I don't want to use .b3d files.

--EDIT--

I can't see to get ODE trimesh creation function to work.

StaticGeom is a big collapsed section of the map. It has a vertex and an indice buffer:

'Buid physics collision data
        For staticgeom:TStaticGeom=EachIn TStaticGeom.list
                trimeshdata=dGeomTriMeshDataCreate()
                staticgeom.odevertexarray:TBank=CreateBank(staticgeom.rendersurface.vertexarray.size()/12*12)
                For n=0 To staticgeom.rendersurface.vertexarray.size()/4-1'12-1
                        PokeFloat staticgeom.odevertexarray,n*4,PeekFloat(staticgeom.rendersurface.vertexarray,n*4)*ODE_WORLDSCALE
                Next
                staticgeom.odeindicearray:TBank=CreateBank(staticgeom.rendersurface.indicearray.size()*2)
                For n=0 To staticgeom.rendersurface.indicearray.size()/6-1
                        PokeInt staticgeom.odeindicearray,n*12+0,PeekShort(staticgeom.rendersurface.indicearray,n*6+0)
                        PokeInt staticgeom.odeindicearray,n*12+4,PeekShort(staticgeom.rendersurface.indicearray,n*6+2)
                        PokeInt staticgeom.odeindicearray,n*12+8,PeekShort(staticgeom.rendersurface.indicearray,n*6+4)
                Next

                dGeomTriMeshDataBuildSimple trimeshdata,staticgeom.odevertexarray.buf(),staticgeom.odevertexarray.size()/12,staticgeom.odeindicearray.buf(),staticgeom.odeindicearray.size()/4
                trimesh=dCreateTriMesh(ODE_space,trimeshdata)

        Next

I tried flipping the faces, and objects pass right through the scene, with no collision.

Here you go, this is the CreateTriMesh() function from JV-ODE BMax which should provide all of the info needed...

' ###################################################################################################

Function CreateTriMesh:Int(trispace:Int,xscale:Float=1.0,yscale:Float=1.0,zscale:Float=1.0)

Global TriBank:TBank=CreateBank(NTris*3*4)
Global VertBank:TBank=CreateBank(NVerts*4*4)

Local Offset:Int=0
Local TriOffset:Int=0

Local VertData:Vrts
Local TriData:Tris

For VertData:Vrts=EachIn B3DVrtsList
	PokeFloat(VertBank,Offset,xscale*VertData.X)
	Offset:+4
	PokeFloat(VertBank,Offset,yscale*VertData.Y)
	Offset:+4
	PokeFloat(VertBank,Offset,zscale*VertData.Z)
	Offset:+8
Next

For TriData:Tris=EachIn B3DTrisList
	PokeInt(TriBank,TriOffset,TriData.V0)
	TriOffset:+4
	PokeInt(TriBank,TriOffset,TriData.V1)
	TriOffset:+4
	PokeInt(TriBank,TriOffset,TriData.V2)
	TriOffset:+4
Next

Local TriMeshData:Int=dGeomTriMeshDataCreate()

dGeomTriMeshDataBuildSimple(TriMeshData,BankBuf(VertBank),NVerts,BankBuf(TriBank),NTris*3)

Return dCreateTriMesh(trispace,TriMeshData)

End Function

' ###################################################################################################

B3DVrtsList contains the vertex array list and B3DTrisList contains the indice array list.

Note the vertex array (X/Y/Z) is poked into the bank, then you offset the bank by an extra 4 bytes as ODE expects (X/Y/Z/*).

Let me know if you need more help with it ;)

Thank you.

Hmm, that's exactly what I am doing, but my collisions still fail.

Double check you are supplying the correct data to the dGeomTriMeshDataBuildSimple() function...

Vertex Array (X/Y/Z/0) 16 bytes per vertex
Vertex Quantity (*1)
Indice Array (V0/V1/V2) 12 bytes per indice
Indice Quantity (*3)

If you don't supply the function with the exact data structure above, then the collisions will fail due to the mesh geom being built incorrectly internally.

What type of mesh are you using?

There was another CreateTriMesh() function by another user (KronosUK) for the BMax version, it's in the previous JV-ODE thread (7). Take a look at that and see if it helps too.

If you still have no luck, feel free to send a copy of the mesh over and I'll take a closer look at it for you.

JV-ODE V1.20 Update Released

Please check your inbox :)

JV-ODE is now compiled using ODE V0.7 which was released recently. To view the changes made to ODE, please visit the following ODE Wiki link: http://opende.sourceforge.net/wiki/index.php/Changelog

Added new functions:
dCreateHeightfield()
dGeomHeightfieldDataCreate()
dGeomHeightfieldDataDestroy()
dGeomHeightfieldDataBuildSingle()
dGeomHeightfieldDataSetBounds()
dGeomHeightfieldSetHeightfieldData()
dGeomHeightfieldGetHeightfieldData()
dJointCreatePlane2D()
dJointSetPlane2DXParam()
dJointSetPlane2DYParam()
dJointSetPlane2DAngleParam()

Added new demos:
CarDemo-See-Saw
Demo-2DSpheres
Demo-CollisionForces
Demo-TriMeshes

It should be easier to build 2D simulations now that an official 2D joint has been added.

'TriMesh to TriMesh' collisions are now working in ODE, but they're slow so use with care. The flat-ended cylinder geom now collides with TriMeshes in V0.7 of ODE, but they've broken the 'Cylinder to Cylinder' and 'Cylinder to Plane' collisions so I've used the previous stable version (the same as in previous JV-ODE versions) until they fix it.

Please let me know if you experience any problems with the new update.

:)

Thanks again vip3r,

Is there a clear overview (or a list) somewhere to find out exactly which geometry shapes don't collide properly with each other? Like trimesh vs pillshaped or flat-capped cylinders.... And now introducing the new 'heightfield' type of geometry and 2D stuff... ?!?

It's getting a tad confusion, and I'd like to know what 'not to use' untill they've been fixed and proven to work...

Danny

You're welcome :)

Flat-ended cylinders have always had collision issues and should be avoided if possible, in most cases you can use capsules (capped cylinders) instead.

The heightfield geom is bound to have teething problems as it's a new addition to the library, I haven't tried them yet so I've no idea.

Everything else (cubes, spheres, capsules, rays, trimeshes and planes) should collide fine.

Super big up for a serious guy. Thanks.. (heu french people. Don't worry about my english)

JPierre

Cool, thanks! Can I now create [heightfield type of] terrain (or something) using Heightfield functions? Would that be faster than trimesh-trimesh or more stable? Give me a demo! :)

You're welcome Mustang :)

No idea about the speed or stability compared to TriMesh, as soon as I've figured out how it works I'll build a demo for you ;)

Firstly thank you for the latest update. JV-ODE has been the best addon purchase I've made since being a Blitz3D user.

I've built a 3D scene with various static geometry, and a single ball bouncing around happily inside it.

I want to control the ball separately from the rest of the scene, i.e. the angle and velocity it moves at. I assume I would need to stop it being affected by gravity too - but I'm thinking that forcibly setting the angle and velocity would override gravity?

I have been trying to use the command:

dGeomGetRotation(geom)

The manual states this returns a vector, but I'm not sure how to define a vector and hence get the angle. Could you give an example?

You're welcome sonic, thanks :)

Gravity will counteract your forces, so you may need to disable it depending on your needs. You can use the dBodySetGravityMode(body,mode) function to disable gravity per body. Use mode '0' to disable.

To return a vector from the geom rotation, you first call the rotation function, then you call the JV-ODE vector functions to return the vector values...

dGeomGetRotation(geom)
Pitch#=dVectorX()
Yaw#=dVectorY()
Roll#=dVectorZ()

Or, alternatively you can call the following unique JV-ODE functions instead...

Pitch#=dGeomGetPitch(geom)
Yaw#=dGeomGetYaw(geom)
Roll#=dGeomGetRoll(geom)

Ah that's great - thanks! Will give it a go.

Ok thanks - I'm making progress now!

Next question is - say I want to introduce another object (say a bat, ala breakout games) to my scene, to be controlled by the player's mouse. This will be the player's piece.

I'm using:
dGeomSetPosition(obj\geom, (MouseX() - graphicswidth/2) / 8, 10, 0)

This positions the bat in the right place... however I get unpredictable results when moving the bat quickly and hitting the ball. For example, a very fast movement of the bat may mean the collision is missed, or the wrong side of the player's piece collides.

Any ideas what I can do to fix it? I'm looking at the hi speed car demo, however once again I've had a couple of beers and my concentration is drifting again :)

Manual positioning of geoms in real-time will upset the ODE simulation, the correct way would be to add force to the bat to make it move. You also might need to zero (or counteract) the forces on the Z and Y axis of the bat to prevent the ball from pushing it up/down etc. A slider joint might work to lock the bat onto the X axis.

To improve the accuracy of the collisions you should use multiple calls to the step/collide functions, the same as in the main loop of the CarDemo-HighSpeed demo.

Ah, I'd guessed as much. I'll change my input so I apply force depending on the speed of the mouse.

I often use transformed geometry but noticed a memory leak when 'trying' to destroy transformed geometry.
Or, let me put it like this; 'What is the proper way to dispose of transformed geometry'?
I thought the 'dGeomTransformSetCleanup(tgeom,1)' would automatically take care of it. But it seems it doesn't. :(

Any ideas anyone??

Here's a little example that when monitored in the Task Manager, you'll see the megabyte disappear in front of your eyes....

; ###################################################################################################

Include "JV-ODE.bb"

Graphics3D 800,600,0,2

; ### Setup ODE

Global World=dWorldCreate()
Global Space=dHashSpaceCreate(0)
Global ContactGroup=dJointGroupCreate(0)

dWorldSetAutoDisableFlag(World,1)
dWorldSetGravity(World,0,-0.98,0)
dWorldSetERP(World,WorldERP)

; ### Options

Cls
Color 255,255,255
Print "RigidBody / Geometry purging test"
Print ""
Print "Note: Watch the Blitzcc.exe process in TaskManager to see the memory crawling up an up :/"
Print ""
Print ""
Print "Choose Option:"
Print " 0 = create rigidbody and main geometry  - 
Print "     purge by removing geometry and rigid body (IS OK)."
Print ""
Print " 1 = create rigidbody and geometry plus a transformed geometry - 
Print "     purge by removing goemetry and rigid body (LEAKY!)"
Print ""
Print ""

; ### options
op$ = Input$("select option: ")
If op<0 Or op>2 Then End
Print ""

Print "Running test - press Escape to stop"
; ### Do test
num = purgingtest(op)
Print "Stopping.."

Print ""
Print "Did "+num+" runs.."

; ### done

Print ""
Print "<any key to exit>"
WaitKey()



; ###################################################################################################

dJointGroupDestroy(ContactGroup)
dSpaceDestroy(Space)
dWorldDestroy(World)
dCloseODE()

End

; ###################################################################################################

Function PurgingTest( option=0)

	While Not KeyHit(1)

		num = num + 1
		
		;-------------------

		;create RIGID BODY
		body = dBodyCreate(world)
		dBodySetRotation body, 0,0,0
		dBodySetPosition body, x,y,z

		;create main GEOMETRY
		geom = dCreateBox(space, 10,10,10)
		dGeomSetBody geom, body
		
		If option = 1 Then
			;add TRANFORMED GEOMETRY
			tgeom = dCreateGeomTransform(space)
			geomObject = dCreateBox(0,1,1,1)
			dGeomSetPosition geomObject, 0,0,0
			dGeomTransformSetGeom tgeom, geomObject
			dGeomTransformSetCleanup tgeom, 1			;SHOULD take care of automatic destruction!?!
			dGeomSetBody tgeom, body
		End If
		
		;-------------------
		;remove geometry then body
		;If tgeom <> 0 Then dGeomDestroy tgeom ;This doesn't help! :(
		dGeomDestroy geom
		dBodyDestroy body

	Wend
	
	FlushKeys
	Return num
	
End Function

; ###################################################################################################

danny

Ah bugger, well done you've found a memory leak indeed.

The collision data isn't being freed by the transform cleanup, that's all done internally in ODE (it isn't aware of the external data structure though).

The only way around this problem will probably be a new unique function, something like...

dGeomTransformDestroyData(tgeom)

...which will need to be called prior to destroying the parent geom.

It'll be fixed in the next update ;)

ok, cheers vip3r,

It would be even greater (if possible) when you'd only have to destroy the main or 'first' geometry - or the rigid body to which the other tgeom's are linked to (or something like that) because else I'd have to store & keep every tgeom handle as well... It's not an impossible task to store the pointers/handles of the geom created, but since (I assume) that data is 'already' stored internally inside ODE, it would make my life easier :)))

thanks,
Danny

If it was possible that would be the way I'd do it, but as the cleanup process is internal it can't be done without hacking the internal ODE stuff. The manual method is the only decent solution I can think of, I certainly don't intend to interfere with the inner workings of ODE to solve the problem.

Besides, storing the handles of the transform geoms should be done in any case, what if you decide you need to retrieve the transform geom collision data at some point? You will need access to those handles to do it.

Sorry, don't completely understand, so is the leak a JV- problem or an internal ODE problem?

If I need to store all handles, then I've got no choice but to do so ofcourse. But can't I get the tgeom handle (to check a collision) from using the 'getCollisionGeom' functions for example?! (sorry - havent got ode here, don't know the exact function name). In each body or geometry I create, I always use the 'user data' field to store a pointer to my internal game-database, so at collision time, I can retrieve 'what object' collided with what other object, and ode can tell me where and with what force... The slightly anoying thing is that my game objects can have anything between 0 and n geometries, and so far I have been able to get away with storing only 1 pointer to the 'main/first' geometry which I use to position my entities during the main loop. So if I can have a working system without having to store all other 'unknown amount' of geoms, that'd be nice - if you know what I mean..

thanks dude,
D

Well the data structure is defined by ODE itself, but it's up to the user to create it for each geom object. In JV-ODE this is done for you automatically whenever you create a geom, then when you destroy any geom, JV-ODE will also cleanup any data structure associated with the geom too. The problem here is that when ODE automatically cleans up the transform geoms, it doesn't cleanup any data structures associated with the geom object. There's no way to tell it to do so either, so this is clearly a problem within the transform cleanup process in ODE. Ideally it should be detecting and cleaning up the associated data structure too. It's unlikely that they will do anything about it now as the new Geom Offset feature is a replacement for Geom Transforms.

I've been testing the idea of destroying the data structure manually as I mentioned above, but alas it doesn't work at all. There's definitely something wrong in the ODE transform cleanup process somewhere.

But, I do have a solution which doesn't require modification to JV-ODE and it works 100%.

First you -must- set the transform cleanup mode to zero (disable) for this to work correctly...

dGeomTransformSetCleanup tgeom,0

Next, when you want to destroy the transform and parent geoms, you should do it in the following order...

dGeomDestroy geomObject
dGeomDestroy tgeom
dGeomDestroy geom
dBodyDestroy body

Then you will see that everything is cleaned up correctly and thus there's no memory leak.

Doing the above means you would need access to both the GeomObject and TGeom handles. If you didn't want to store all of the handles (they would only use 4 bytes each btw), you're right it might be possible to use dGeomTransformGetGeom(geom) instead.

ok that's cool. Thanks for explaining that...
I can check & test this tomorrow..

But before I do that, you did touch another question I've been wanting to ask for a while.. :)

You mention that the 'geom transforms' (which require you to create a Geometry to 0-space PLUS a tranformed geometry in your default 'Space' -as in my example code above) have been replaced by the Geom-Offset functions - this (and the docs) suggested to me that I can create 1 single geometry (as you normally do) and simply offset it's position & rotation using those two functions... But that doesn't seem to work!?!?! In my situation at least...

So, am I doing something wrong? Are there any examples on how to use them? I was starting to think those offset functions were made to 'further offset' or 'alter' an already off-set trans geom at run-time or something.. But I haven't tested this yet.. dunno.. Bit stuck on that one.. :)

D.

No problem :)

I haven't experimented with Geom Offsets yet, although it's simple enough to add the API for these features to JV-ODE, there's very little (if any) info on their usage at the moment as they're mostly undocumented. As far as I know you would create the geom normally, add it to the body, then offset it. For multiple geoms I'd imagine you add each of them to the body and offset them as needed.

The same is the case for the new heightfield geoms, I've no idea how those work either yet because again there's not enough info available on their usage.

As soon as I've figured out the correct usage of these features I'll provide demos to show them in action if possible, but until I have the necessary info it's going to be very difficult to put something together unfortunately.

I am trying to make a AI for cars using the ODE, but, unhappyly I am not obtaining to make the cars point to the Waypoints, or either, I do not obtain to make the vehicles follow the track.

Maybe somebody that already made this could help me or show the way for me?

@EmerGki: KuRiX has done some great AI work in his Granada Racer with ODE, he would probably be the best person to help you.

Here's four new demos to show how Geom Offsets are used. Geom Offsets are the replacement for the now obsolete Geom Transforms in ODE.

Geom Offset - Car

; ###################################################################################################
; #										  JV-ODE Car Demo											#
; #									Code by Jim Williams (VIP3R)									#
; #								Devious Codeworks - Copyright © 2006								#
; ###################################################################################################

AppTitle "JV-ODE Car Demo - Geom Offset - Car"

Include "JV-ODE.bb"

Graphics3D 800,600,0,2

Global CMass#=200			; ### Car Mass
Global WMass#=14			; ### Wheel Mass

Global WorldERP#=1			; ### World Error Correction
Global WorldFriction#=140	; ### World Friction

Global Torque#=24			; ### Joint Torque
Global SuspensionHS#=0.01	; ### Suspension Hardness/Softness (Higher=Softer - Lower=Harder)

Global Force#=0
Global Steer#=0

Global Car
Global CGeom
Global CMesh

Global CarStartY=20

Dim Wheel(4)
Dim WGeom(4)
Dim Joint(4)

Type ODEGeom
	Field body
	Field geom
	Field mesh
End Type

; ###################################################################################################

; ### Setup ODE

Global World=dWorldCreate()
Global Space=dHashSpaceCreate(0)
Global ContactGroup=dJointGroupCreate(0)

dWorldSetAutoDisableFlag(World,1)
dWorldSetGravity(World,0,-0.98,0)
dWorldSetERP(World,WorldERP)

dContactSetMode(dContactSlip1)
dContactSetMu(WorldFriction)

; ### Create car body

ode.ODEGeom=New ODEGeom
ode\body=dBodyCreate(World)
Car=ode\body
dBodySetRotation(ode\body,0,0,0)
dBodySetPosition(ode\body,0,CarStartY-1,0)
mass=dMassCreate()
dMassSetBoxTotal(mass,CMass,3,1,4)
dBodySetMass(ode\body,mass)
dMassDestroy(mass)
ode\geom=dCreateBox(Space,0,0,0)
CGeom=ode\geom
dGeomSetBody(ode\geom,ode\body)
ode\mesh=CreateCube()
CMesh=ode\mesh
ScaleMesh ode\mesh,1.5,0.5,2
RotateMesh ode\mesh,0,0,0
PositionMesh ode\mesh,0,0,0
EntityColor ode\mesh,255,40,80
EntityAlpha ode\mesh,0.4

GeomObject=dCreateBox(Space,3,1,4)
dGeomSetBody(GeomObject,ode\body)
dGeomSetOffsetPosition(GeomObject,0,1,0)

GeomMesh=CreateCube(ode\mesh)
ScaleMesh GeomMesh,1.5,0.5,2
RotateMesh GeomMesh,0,0,0
PositionMesh GeomMesh,0,1,0
EntityColor GeomMesh,40,80,255
EntityAlpha GeomMesh,0.7
EntityShininess GeomMesh,0.7

; ### Create wheels

For count=1 To 4
	ode.ODEGeom=New ODEGeom
	ode\body=dBodyCreate(World)
	Wheel(count)=ode\body
	dBodySetRotation(ode\body,0,0,0)
	dBodySetPosition(ode\body,0,0,0)
	mass=dMassCreate()
	dMassSetSphereTotal(mass,WMass,0.7)
	dBodySetMass(ode\body,mass)
	dMassDestroy(mass)
	ode\geom=dCreateSphere(Space,0.7)
	WGeom(count)=ode\geom
	dGeomSetBody(ode\geom,ode\body)
	ode\mesh=CreateCylinder(8)
	ScaleMesh ode\mesh,0.7,0.25,0.7
	RotateMesh ode\mesh,0,0,90
	PositionMesh ode\mesh,0,0,0
	EntityColor ode\mesh,255,255,255
Next

dBodySetPosition(Wheel(1),-2,CarStartY-0.5,+2)
dBodySetPosition(Wheel(2),+2,CarStartY-0.5,+2)
dBodySetPosition(Wheel(3),-2,CarStartY-0.5,-2)
dBodySetPosition(Wheel(4),+2,CarStartY-0.5,-2)

; ### Create some objects

SeedRnd MilliSecs()

For spheres=1 To 20
	ode.ODEGeom=New ODEGeom
	ode\body=dBodyCreate(World)
	dBodySetRotation(ode\body,0,0,0)
	dBodySetPosition(ode\body,Rnd(-100,100),30,Rnd(-100,100))
	ode\geom=dCreateSphere(Space,4)
	dGeomSetBody(ode\geom,ode\body)
	ode\mesh=CreateSphere()
	ScaleMesh ode\mesh,4,4,4
	RotateMesh ode\mesh,0,0,0
	PositionMesh ode\mesh,0,0,0
	EntityColor ode\mesh,Rnd(255),Rnd(255),Rnd(255)
	EntityAlpha ode\mesh,1
	EntityShininess ode\mesh,0.7
Next

For capsules=1 To 20
	ode.ODEGeom=New ODEGeom
	ode\body=dBodyCreate(World)
	dBodySetRotation(ode\body,90,0,0)
	dBodySetPosition(ode\body,Rnd(-100,100),30,Rnd(-100,100))
	ode\geom=dCreateCapsule(Space,1,8)
	dGeomSetBody(ode\geom,ode\body)
	ode\mesh=CreateCylinder(8)
	ScaleMesh ode\mesh,1,5,1
	RotateMesh ode\mesh,90,0,0	; <<< Mesh X-Axis must be rotated 90 degrees to fix cylinder alignment
	PositionMesh ode\mesh,0,0,0
	EntityColor ode\mesh,Rnd(255),Rnd(255),Rnd(255)
	EntityAlpha ode\mesh,1
	EntityShininess ode\mesh,0.7
Next

; ### Create light

Global Light=CreateLight()

RotateEntity Light,45,-90,0
LightColor Light,255,255,255
AmbientLight 130,130,130

; ### Create camera

Global CameraPivot=CreatePivot(CMesh)
PositionEntity CameraPivot,0,2,-7

Global Camera=CreateCamera()
CameraClsColor Camera,0,0,0
CameraRange Camera,1,1000

; ### Create plane

dCreatePlane(Space,0,1,0,0)

Plane=CreatePlane()

EntityAlpha Plane,0.8

PlaneTexture=CreateTexture(128,128,9)

ClsColor 0,200,80
Cls

Color 255,255,255

Rect 0,0,64,64,1
Rect 64,64,64,64,1

CopyRect 0,0,128,128,0,0,BackBuffer(),TextureBuffer(PlaneTexture)
ScaleTexture PlaneTexture,20,20
EntityTexture Plane,PlaneTexture,0,0

Mirror=CreateMirror()

; ###################################################################################################

; ### BLITZ STATIC OBJECT (White)

blitzobject=CreateCube()
ScaleMesh blitzobject,1,4,20
RotateMesh blitzobject,-10,8,4
PositionMesh blitzobject,10,5,40

EntityColor blitzobject,255,255,255
EntityAlpha blitzobject,1

; ### ODE STATIC OBJECT (Blue)

ode.ODEGeom=New ODEGeom
ode\geom=dCreateBox(Space,2,8,40)
dGeomSetRotation(ode\geom,-10,8,4)
dGeomSetPosition(ode\geom,20,5,40)
ode\mesh=CreateCube()
ScaleMesh ode\mesh,1,4,20
RotateMesh ode\mesh,0,0,0
PositionMesh ode\mesh,0,0,0

EntityColor ode\mesh,0,100,200
EntityAlpha ode\mesh,1

; ### ODE STATIC OBJECT (Red)

ode.ODEGeom=New ODEGeom
ode\geom=dCreateBox(Space,18,0.2,40)
dGeomSetRotation(ode\geom,-14,0,0)
dGeomSetPosition(ode\geom,-20,4.9,40)
ode\mesh=CreateCube()
ScaleMesh ode\mesh,9,0.1,20
RotateMesh ode\mesh,0,0,0
PositionMesh ode\mesh,0,0,0

EntityColor ode\mesh,200,0,100
EntityAlpha ode\mesh,1

; ###################################################################################################

SetupCar()

While Not KeyHit(1)

	UpdateKeys()

	PTime=MilliSecs()

	UpdateCar()

	UpdateGeoms()

	dSpaceCollide(Space,World,ContactGroup)
	dWorldQuickStep(World,0.1)
	dJointGroupEmpty(ContactGroup)

	PhysicsTime#=MilliSecs()-PTime

	UpdateCam()

	UpdateWorld

	RenderWorld

	Text 0,0,"JV-ODE Version "+dGetVersion()
	Text 0,15,"Physics Time:"+PhysicsTime
	Text 0,50,"Force:"+Force
	Text 0,65,"Torque:"+Torque
	Text 0,100,"Blue = Geom Offset"
	Text 0,115,"Red = Body/Mass Position"
	Text 640,0,"A - Accelerate"
	Text 640,15,"Z - Brake/Reverse"
	Text 640,30,"Arrows - Steering"
	Text 640,45,"Space - Reset Car"

	Flip

Wend

dJointGroupDestroy(ContactGroup)
dSpaceDestroy(Space)
dWorldDestroy(World)
dCloseODE()

End

; ###################################################################################################

Function SetupCar()

For count=1 To 4
	Joint(count)=dJointCreateHinge2(World,0)
	dJointAttach(Joint(count),Car,Wheel(count))
	dJointSetHinge2Anchor(Joint(count),dBodyGetPositionX(Wheel(count)),dBodyGetPositionY(Wheel(count)),dBodyGetPositionZ(Wheel(count)))
	dJointSetHinge2Axis1(Joint(count),0,1,0)
	dJointSetHinge2Axis2(Joint(count),-1,0,0)
	dJointSetHinge2Param(Joint(count),dParamSuspensionERP,0.8)
	dJointSetHinge2Param(Joint(count),dParamSuspensionCFM,SuspensionHS)
	If count>2
		dJointSetHinge2Param(Joint(count),dParamLoStop,0)
		dJointSetHinge2Param(Joint(count),dParamHiStop,0)
		End If
Next

Force=0

End Function

; ###################################################################################################

Function UpdateKeys()

If KeyDown(30)=1
	Force=Force+0.08
	If Force>30 Then Force=30
	End If

If KeyDown(44)=1
	Force=Force-0.1
	If Force<-10 Then Force=-10
	If Force>0 Then Force=Force*0.97
	End If

If KeyDown(30)=0 And KeyDown(44)=0 Then Force=Force*0.99

If KeyDown(203)=1 Or KeyDown(205)=1
	If KeyDown(203)=1
		Steer=0.5
		Else
		Steer=-0.5
		End If
	Else
	Steer=0
	End If

If KeyHit(57)=1
	Force=0
	dBodySetRotation(Car,dGeomGetPitch#(CGeom),dGeomGetYaw#(CGeom),0)
	End If

End Function

; ###################################################################################################

Function UpdateCar()

For count=1 To 4
	dBodyEnable(Wheel(count))
Next

dBodyEnable(Car)

For count=1 To 4
	dJointSetHinge2Param(Joint(count),dParamVel2,Force)
	dJointSetHinge2Param(Joint(count),dParamFMax2,Torque)
Next

For count=1 To 2
	angle#=Steer-dJointGetHinge2Angle1(Joint(count))
	dJointSetHinge2Param(Joint(count),dParamVel,angle)
	dJointSetHinge2Param(Joint(count),dParamFMax,400)
Next

End Function

; ###################################################################################################

Function UpdateCam()

PositionEntity CameraPivot,0,3,-12

camx#=EntityX(CameraPivot,1)-EntityX(Camera)
camy#=EntityY(CameraPivot,1)-EntityY(Camera)
camz#=EntityZ(CameraPivot,1)-EntityZ(Camera)

TranslateEntity Camera,camx*0.5,camy*0.5,camz*0.5

PointEntity Camera,CMesh

End Function

; ###################################################################################################

Function UpdateGeoms()

For ode.ODEGeom=Each ODEGeom
	RotateEntity ode\mesh,dGeomGetPitch#(ode\geom),dGeomGetYaw#(ode\geom),dGeomGetRoll#(ode\geom)
	PositionEntity ode\mesh,dGeomGetPositionX#(ode\geom),dGeomGetPositionY#(ode\geom),dGeomGetPositionZ#(ode\geom)
Next

End Function

; ###################################################################################################

Geom Offset - Cube

; ###################################################################################################
; #										  JV-ODE Car Demo											#
; #									Code by Jim Williams (VIP3R)									#
; #								Devious Codeworks - Copyright © 2006								#
; ###################################################################################################

AppTitle "JV-ODE Car Demo - Geom Offset - Cube"

Include "JV-ODE.bb"

Graphics3D 800,600,0,2

Global CMass#=200			; ### Car Mass
Global WMass#=14			; ### Wheel Mass

Global WorldERP#=1			; ### World Error Correction
Global WorldFriction#=70	; ### World Friction

Global Torque#=24			; ### Joint Torque
Global SuspensionHS#=0.01	; ### Suspension Hardness/Softness (Higher=Softer - Lower=Harder)

Global Force#=0
Global Steer#=0

Global Car
Global CGeom
Global CMesh

Global CarStartY=10

Dim Wheel(4)
Dim WGeom(4)
Dim Joint(4)

Type ODEGeom
	Field body
	Field geom
	Field mesh
End Type

; ###################################################################################################

; ### Setup ODE

Global World=dWorldCreate()
Global Space=dHashSpaceCreate(0)
Global ContactGroup=dJointGroupCreate(0)

dWorldSetAutoDisableFlag(World,1)
dWorldSetGravity(World,0,-0.98,0)
dWorldSetERP(World,WorldERP)

dContactSetMode(dContactSlip1)
dContactSetMu(WorldFriction)

; ### Create car body

ode.ODEGeom=New ODEGeom
ode\body=dBodyCreate(World)
Car=ode\body
dBodySetRotation(ode\body,0,0,0)
dBodySetPosition(ode\body,0,CarStartY,0)
mass=dMassCreate()
dMassSetBoxTotal(mass,CMass,3,1,4)
dMassTranslate(mass,0,-1,0)
dBodySetMass(ode\body,mass)
dMassDestroy(mass)
ode\geom=dCreateBox(Space,3,1,4)
CGeom=ode\geom
dGeomSetBody(ode\geom,ode\body)
ode\mesh=CreateCube()
CMesh=ode\mesh
ScaleMesh ode\mesh,1.5,0.5,2
RotateMesh ode\mesh,0,0,0
PositionMesh ode\mesh,0,0,0
EntityColor ode\mesh,40,80,255
EntityAlpha ode\mesh,1

; ### Create wheels

For count=1 To 4
	ode.ODEGeom=New ODEGeom
	ode\body=dBodyCreate(World)
	Wheel(count)=ode\body
	dBodySetRotation(ode\body,0,0,0)
	dBodySetPosition(ode\body,0,0,0)
	mass=dMassCreate()
	dMassSetSphereTotal(mass,WMass,0.7)
	dBodySetMass(ode\body,mass)
	dMassDestroy(mass)
	ode\geom=dCreateSphere(Space,0.7)
	WGeom(count)=ode\geom
	dGeomSetBody(ode\geom,ode\body)
	ode\mesh=CreateCylinder(8)
	ScaleMesh ode\mesh,0.7,0.25,0.7
	RotateMesh ode\mesh,0,0,90
	PositionMesh ode\mesh,0,0,0
	EntityColor ode\mesh,255,255,255
Next

dBodySetPosition(Wheel(1),-2,CarStartY-0.5,+2)
dBodySetPosition(Wheel(2),+2,CarStartY-0.5,+2)
dBodySetPosition(Wheel(3),-2,CarStartY-0.5,-2)
dBodySetPosition(Wheel(4),+2,CarStartY-0.5,-2)

; ### Create light

Global Light=CreateLight()

RotateEntity Light,45,-90,0
LightColor Light,255,255,255
AmbientLight 130,130,130

; ### Create camera

Global CameraPivot=CreatePivot(CMesh)
PositionEntity CameraPivot,0,2,-7

Global Camera=CreateCamera()
CameraClsColor Camera,0,0,0
CameraRange Camera,1,1000

; ### Create plane

dCreatePlane(Space,0,1,0,0)

Plane=CreatePlane()

EntityAlpha Plane,0.8

PlaneTexture=CreateTexture(128,128,9)

ClsColor 0,200,80
Cls

Color 255,255,255

Rect 0,0,64,64,1
Rect 64,64,64,64,1

CopyRect 0,0,128,128,0,0,BackBuffer(),TextureBuffer(PlaneTexture)
ScaleTexture PlaneTexture,20,20
EntityTexture Plane,PlaneTexture,0,0

Mirror=CreateMirror()

; ###################################################################################################

SetupCar()

SetupObjects()

While Not KeyHit(1)

	UpdateKeys()

	PTime=MilliSecs()

	UpdateCar()

	UpdateGeoms()

	dSpaceCollide(Space,World,ContactGroup)
	dWorldQuickStep(World,0.1)
	dJointGroupEmpty(ContactGroup)

	PhysicsTime#=MilliSecs()-PTime

	UpdateCam()

	UpdateWorld

	RenderWorld

	Text 0,0,"JV-ODE Version "+dGetVersion()
	Text 0,15,"Physics Time:"+PhysicsTime
	Text 0,50,"Force:"+Force
	Text 0,65,"Torque:"+Torque
	Text 640,0,"A - Accelerate"
	Text 640,15,"Z - Brake/Reverse"
	Text 640,30,"Arrows - Steering"
	Text 640,45,"Space - Reset Car"

	Flip

Wend

dJointGroupDestroy(ContactGroup)
dSpaceDestroy(Space)
dWorldDestroy(World)
dCloseODE()

End

; ###################################################################################################

Function SetupCar()

For count=1 To 4
	Joint(count)=dJointCreateHinge2(World,0)
	dJointAttach(Joint(count),Car,Wheel(count))
	dJointSetHinge2Anchor(Joint(count),dBodyGetPositionX(Wheel(count)),dBodyGetPositionY(Wheel(count)),dBodyGetPositionZ(Wheel(count)))
	dJointSetHinge2Axis1(Joint(count),0,1,0)
	dJointSetHinge2Axis2(Joint(count),-1,0,0)
	dJointSetHinge2Param(Joint(count),dParamSuspensionERP,0.8)
	dJointSetHinge2Param(Joint(count),dParamSuspensionCFM,SuspensionHS)
	If count>2
		dJointSetHinge2Param(Joint(count),dParamLoStop,0)
		dJointSetHinge2Param(Joint(count),dParamHiStop,0)
		End If
Next

Force=0

End Function

; ###################################################################################################

Function SetupObjects()

For count=1 To 30
	AddObjects((xp*34)-120,17,(zp*34)+100)

	xp=xp+1
	If xp>7
		xp=0
		zp=zp+1
		End If
Next

End Function

; ###################################################################################################

Function AddObjects(objectxp,objectyp,objectzp)

ode.ODEGeom=New ODEGeom
ode\body=dBodyCreate(World)
dBodySetRotation(ode\body,0,0,0)
dBodySetPosition(ode\body,objectxp,objectyp,objectzp)
ode\geom=dCreateBox(Space,14,14,14)
dGeomSetBody(ode\geom,ode\body)

ode\mesh=CreateCube()
ScaleMesh ode\mesh,7,7,7
RotateMesh ode\mesh,0,0,0
PositionMesh ode\mesh,0,0,0
EntityColor ode\mesh,255,255,255
EntityAlpha ode\mesh,0.8
EntityShininess ode\mesh,0.7

transxp=-7
transyp=0

For count=1 To 3
	GeomObject=dCreateBox(Space,7,7,7)
	dGeomSetBody(GeomObject,ode\body)
	dGeomSetOffsetPosition(GeomObject,transxp,transyp,0)

	GeomMesh=CreateCube(ode\mesh)
	ScaleMesh GeomMesh,3.5,3.5,3.5
	RotateMesh GeomMesh,0,0,0
	PositionMesh GeomMesh,transxp,transyp,0
	EntityColor GeomMesh,count*10,count*70,255
	EntityAlpha GeomMesh,1
	EntityShininess GeomMesh,0.7

	If count=2
		transxp=0
		transyp=-7
		Else
		transxp=transxp+14
		End If
Next

End Function

; ###################################################################################################

Function UpdateKeys()

If KeyDown(30)=1
	Force=Force+0.08
	If Force>30 Then Force=30
	End If

If KeyDown(44)=1
	Force=Force-0.1
	If Force<-10 Then Force=-10
	If Force>0 Then Force=Force*0.97
	End If

If KeyDown(30)=0 And KeyDown(44)=0 Then Force=Force*0.99

If KeyDown(203)=1 Or KeyDown(205)=1
	If KeyDown(203)=1
		Steer=0.5
		Else
		Steer=-0.5
		End If
	Else
	Steer=0
	End If

If KeyHit(57)=1
	Force=0
	dBodySetRotation(Car,dGeomGetPitch#(CGeom),dGeomGetYaw#(CGeom),0)
	End If

End Function

; ###################################################################################################

Function UpdateCar()

For count=1 To 4
	dBodyEnable(Wheel(count))
Next

dBodyEnable(Car)

For count=1 To 4
	dJointSetHinge2Param(Joint(count),dParamVel2,Force)
	dJointSetHinge2Param(Joint(count),dParamFMax2,Torque)
Next

For count=1 To 2
	angle#=Steer-dJointGetHinge2Angle1(Joint(count))
	dJointSetHinge2Param(Joint(count),dParamVel,angle)
	dJointSetHinge2Param(Joint(count),dParamFMax,400)
Next

End Function

; ###################################################################################################

Function UpdateCam()

PositionEntity CameraPivot,0,3,-10

camx#=EntityX(CameraPivot,1)-EntityX(Camera)
camy#=EntityY(CameraPivot,1)-EntityY(Camera)
camz#=EntityZ(CameraPivot,1)-EntityZ(Camera)

TranslateEntity Camera,camx*0.5,camy*0.5,camz*0.5

PointEntity Camera,CMesh

End Function

; ###################################################################################################

Function UpdateGeoms()

For ode.ODEGeom=Each ODEGeom
	RotateEntity ode\mesh,dGeomGetPitch#(ode\geom),dGeomGetYaw#(ode\geom),dGeomGetRoll#(ode\geom)
	PositionEntity ode\mesh,dGeomGetPositionX#(ode\geom),dGeomGetPositionY#(ode\geom),dGeomGetPositionZ#(ode\geom)
Next

End Function

; ###################################################################################################

Geom Offset - Mixed

; ###################################################################################################
; #										  JV-ODE Car Demo											#
; #									Code by Jim Williams (VIP3R)									#
; #								Devious Codeworks - Copyright © 2006								#
; ###################################################################################################

AppTitle "JV-ODE Car Demo - Geom Offset - Mixed"

Include "JV-ODE.bb"

Graphics3D 800,600,0,2

Global CMass#=200			; ### Car Mass
Global WMass#=14			; ### Wheel Mass

Global WorldERP#=1			; ### World Error Correction
Global WorldFriction#=70	; ### World Friction

Global Torque#=24			; ### Joint Torque
Global SuspensionHS#=0.01	; ### Suspension Hardness/Softness (Higher=Softer - Lower=Harder)

Global Force#=0
Global Steer#=0

Global Car
Global CGeom
Global CMesh

Global CarStartY=10

Dim Wheel(4)
Dim WGeom(4)
Dim Joint(4)

Type ODEGeom
	Field body
	Field geom
	Field mesh
End Type

; ###################################################################################################

; ### Setup ODE

Global World=dWorldCreate()
Global Space=dHashSpaceCreate(0)
Global ContactGroup=dJointGroupCreate(0)

dWorldSetAutoDisableFlag(World,1)
dWorldSetGravity(World,0,-0.98,0)
dWorldSetERP(World,WorldERP)

dContactSetMode(dContactSlip1)
dContactSetMu(WorldFriction)

; ### Create car body

ode.ODEGeom=New ODEGeom
ode\body=dBodyCreate(World)
Car=ode\body
dBodySetRotation(ode\body,0,0,0)
dBodySetPosition(ode\body,0,CarStartY,0)
mass=dMassCreate()
dMassSetBoxTotal(mass,CMass,3,1,4)
dMassTranslate(mass,0,-1,0)
dBodySetMass(ode\body,mass)
dMassDestroy(mass)
ode\geom=dCreateBox(Space,3,1,4)
CGeom=ode\geom
dGeomSetBody(ode\geom,ode\body)
ode\mesh=CreateCube()
CMesh=ode\mesh
ScaleMesh ode\mesh,1.5,0.5,2
RotateMesh ode\mesh,0,0,0
PositionMesh ode\mesh,0,0,0
EntityColor ode\mesh,40,80,255
EntityAlpha ode\mesh,1

; ### Create wheels

For count=1 To 4
	ode.ODEGeom=New ODEGeom
	ode\body=dBodyCreate(World)
	Wheel(count)=ode\body
	dBodySetRotation(ode\body,0,0,0)
	dBodySetPosition(ode\body,0,0,0)
	mass=dMassCreate()
	dMassSetSphereTotal(mass,WMass,0.7)
	dBodySetMass(ode\body,mass)
	dMassDestroy(mass)
	ode\geom=dCreateSphere(Space,0.7)
	WGeom(count)=ode\geom
	dGeomSetBody(ode\geom,ode\body)
	ode\mesh=CreateCylinder(8)
	ScaleMesh ode\mesh,0.7,0.25,0.7
	RotateMesh ode\mesh,0,0,90
	PositionMesh ode\mesh,0,0,0
	EntityColor ode\mesh,255,255,255
Next

dBodySetPosition(Wheel(1),-2,CarStartY-0.5,+2)
dBodySetPosition(Wheel(2),+2,CarStartY-0.5,+2)
dBodySetPosition(Wheel(3),-2,CarStartY-0.5,-2)
dBodySetPosition(Wheel(4),+2,CarStartY-0.5,-2)

; ### Create light

Global Light=CreateLight()

RotateEntity Light,45,-90,0
LightColor Light,255,255,255
AmbientLight 130,130,130

; ### Create camera

Global CameraPivot=CreatePivot(CMesh)
PositionEntity CameraPivot,0,2,-7

Global Camera=CreateCamera()
CameraClsColor Camera,0,0,0
CameraRange Camera,1,1000

; ### Create plane

dCreatePlane(Space,0,1,0,0)

Plane=CreatePlane()

EntityAlpha Plane,0.8

PlaneTexture=CreateTexture(128,128,9)

ClsColor 0,200,80
Cls

Color 255,255,255

Rect 0,0,64,64,1
Rect 64,64,64,64,1

CopyRect 0,0,128,128,0,0,BackBuffer(),TextureBuffer(PlaneTexture)
ScaleTexture PlaneTexture,20,20
EntityTexture Plane,PlaneTexture,0,0

Mirror=CreateMirror()

; ###################################################################################################

SetupCar()

SetupObjects()

While Not KeyHit(1)

	UpdateKeys()

	PTime=MilliSecs()

	UpdateCar()

	UpdateGeoms()

	dSpaceCollide(Space,World,ContactGroup)
	dWorldQuickStep(World,0.1)
	dJointGroupEmpty(ContactGroup)

	PhysicsTime#=MilliSecs()-PTime

	UpdateCam()

	UpdateWorld

	RenderWorld

	Text 0,0,"JV-ODE Version "+dGetVersion()
	Text 0,15,"Physics Time:"+PhysicsTime
	Text 0,50,"Force:"+Force
	Text 0,65,"Torque:"+Torque
	Text 640,0,"A - Accelerate"
	Text 640,15,"Z - Brake/Reverse"
	Text 640,30,"Arrows - Steering"
	Text 640,45,"Space - Reset Car"

	Flip

Wend

dJointGroupDestroy(ContactGroup)
dSpaceDestroy(Space)
dWorldDestroy(World)
dCloseODE()

End

; ###################################################################################################

Function SetupCar()

For count=1 To 4
	Joint(count)=dJointCreateHinge2(World,0)
	dJointAttach(Joint(count),Car,Wheel(count))
	dJointSetHinge2Anchor(Joint(count),dBodyGetPositionX(Wheel(count)),dBodyGetPositionY(Wheel(count)),dBodyGetPositionZ(Wheel(count)))
	dJointSetHinge2Axis1(Joint(count),0,1,0)
	dJointSetHinge2Axis2(Joint(count),-1,0,0)
	dJointSetHinge2Param(Joint(count),dParamSuspensionERP,0.8)
	dJointSetHinge2Param(Joint(count),dParamSuspensionCFM,SuspensionHS)
	If count>2
		dJointSetHinge2Param(Joint(count),dParamLoStop,0)
		dJointSetHinge2Param(Joint(count),dParamHiStop,0)
		End If
Next

Force=0

End Function

; ###################################################################################################

Function SetupObjects()

For count=1 To 30
	SeedRnd MilliSecs()

	AddObjects(Rnd(0,1),Rnd(0,1),Rnd(3,5),(xp*34)-120,17,(zp*34)+100)

	xp=xp+1
	If xp>7
		xp=0
		zp=zp+1
		End If
Next

End Function

; ###################################################################################################

Function AddObjects(objecttype,offsettype,transamount,objectxp,objectyp,objectzp)

ode.ODEGeom=New ODEGeom
ode\body=dBodyCreate(World)
dBodySetRotation(ode\body,0,0,0)
dBodySetPosition(ode\body,objectxp,objectyp,objectzp)

If objecttype=0
	ode\geom=dCreateSphere(Space,8)
	Else
	ode\geom=dCreateBox(Space,14,14,14)
	End If

dGeomSetBody(ode\geom,ode\body)

If objecttype=0
	ode\mesh=CreateSphere()
	ScaleMesh ode\mesh,8,8,8
	Else
	ode\mesh=CreateCube()
	ScaleMesh ode\mesh,7,7,7
	End If

RotateMesh ode\mesh,0,0,0
PositionMesh ode\mesh,0,0,0
EntityColor ode\mesh,255,255,255
EntityAlpha ode\mesh,0.8
EntityShininess ode\mesh,0.7

For count=1 To transamount
	If count=1 Then transxp=-7 : transyp=0 : transzp=0
	If count=2 Then transxp=7 : transyp=0 : transzp=0
	If count=3 Then transxp=0 : transyp=-7 : transzp=0
	If count=4 Then transxp=0 : transyp=0 : transzp=-7
	If count=5 Then transxp=0 : transyp=0 : transzp=7

	If offsettype=0
		GeomObject=dCreateSphere(Space,4)
		Else
		GeomObject=dCreateBox(Space,7,7,7)
		End If

	dGeomSetBody(GeomObject,ode\body)
	dGeomSetOffsetPosition(GeomObject,transxp,transyp,transzp)

	If offsettype=0
		GeomMesh=CreateSphere(8,ode\mesh)
		ScaleMesh GeomMesh,4,4,4
		Else
		GeomMesh=CreateCube(ode\mesh)
		ScaleMesh GeomMesh,3.5,3.5,3.5
		End If

	RotateMesh GeomMesh,0,0,0
	PositionMesh GeomMesh,transxp,transyp,transzp
	EntityColor GeomMesh,count*10,count*70,255
	EntityAlpha GeomMesh,1
	EntityShininess GeomMesh,0.7
Next

End Function

; ###################################################################################################

Function UpdateKeys()

If KeyDown(30)=1
	Force=Force+0.08
	If Force>30 Then Force=30
	End If

If KeyDown(44)=1
	Force=Force-0.1
	If Force<-10 Then Force=-10
	If Force>0 Then Force=Force*0.97
	End If

If KeyDown(30)=0 And KeyDown(44)=0 Then Force=Force*0.99

If KeyDown(203)=1 Or KeyDown(205)=1
	If KeyDown(203)=1
		Steer=0.5
		Else
		Steer=-0.5
		End If
	Else
	Steer=0
	End If

If KeyHit(57)=1
	Force=0
	dBodySetRotation(Car,dGeomGetPitch#(CGeom),dGeomGetYaw#(CGeom),0)
	End If

End Function

; ###################################################################################################

Function UpdateCar()

For count=1 To 4
	dBodyEnable(Wheel(count))
Next

dBodyEnable(Car)

For count=1 To 4
	dJointSetHinge2Param(Joint(count),dParamVel2,Force)
	dJointSetHinge2Param(Joint(count),dParamFMax2,Torque)
Next

For count=1 To 2
	angle#=Steer-dJointGetHinge2Angle1(Joint(count))
	dJointSetHinge2Param(Joint(count),dParamVel,angle)
	dJointSetHinge2Param(Joint(count),dParamFMax,400)
Next

End Function

; ###################################################################################################

Function UpdateCam()

PositionEntity CameraPivot,0,3,-10

camx#=EntityX(CameraPivot,1)-EntityX(Camera)
camy#=EntityY(CameraPivot,1)-EntityY(Camera)
camz#=EntityZ(CameraPivot,1)-EntityZ(Camera)

TranslateEntity Camera,camx*0.5,camy*0.5,camz*0.5

PointEntity Camera,CMesh

End Function

; ###################################################################################################

Function UpdateGeoms()

For ode.ODEGeom=Each ODEGeom
	RotateEntity ode\mesh,dGeomGetPitch#(ode\geom),dGeomGetYaw#(ode\geom),dGeomGetRoll#(ode\geom)
	PositionEntity ode\mesh,dGeomGetPositionX#(ode\geom),dGeomGetPositionY#(ode\geom),dGeomGetPositionZ#(ode\geom)
Next

End Function

; ###################################################################################################

Geom Offset - Sphere

; ###################################################################################################
; #										  JV-ODE Car Demo											#
; #									Code by Jim Williams (VIP3R)									#
; #								Devious Codeworks - Copyright © 2006								#
; ###################################################################################################

AppTitle "JV-ODE Car Demo - Geom Offset - Sphere"

Include "JV-ODE.bb"

Graphics3D 800,600,0,2

Global CMass#=200			; ### Car Mass
Global WMass#=14			; ### Wheel Mass

Global WorldERP#=1			; ### World Error Correction
Global WorldFriction#=70	; ### World Friction

Global Torque#=24			; ### Joint Torque
Global SuspensionHS#=0.01	; ### Suspension Hardness/Softness (Higher=Softer - Lower=Harder)

Global Force#=0
Global Steer#=0

Global Car
Global CGeom
Global CMesh

Global CarStartY=10

Dim Wheel(4)
Dim WGeom(4)
Dim Joint(4)

Type ODEGeom
	Field body
	Field geom
	Field mesh
End Type

; ###################################################################################################

; ### Setup ODE

Global World=dWorldCreate()
Global Space=dHashSpaceCreate(0)
Global ContactGroup=dJointGroupCreate(0)

dWorldSetAutoDisableFlag(World,1)
dWorldSetGravity(World,0,-0.98,0)
dWorldSetERP(World,WorldERP)

dContactSetMode(dContactSlip1)
dContactSetMu(WorldFriction)

; ### Create car body

ode.ODEGeom=New ODEGeom
ode\body=dBodyCreate(World)
Car=ode\body
dBodySetRotation(ode\body,0,0,0)
dBodySetPosition(ode\body,0,CarStartY,0)
mass=dMassCreate()
dMassSetBoxTotal(mass,CMass,3,1,4)
dMassTranslate(mass,0,-1,0)
dBodySetMass(ode\body,mass)
dMassDestroy(mass)
ode\geom=dCreateBox(Space,3,1,4)
CGeom=ode\geom
dGeomSetBody(ode\geom,ode\body)
ode\mesh=CreateCube()
CMesh=ode\mesh
ScaleMesh ode\mesh,1.5,0.5,2
RotateMesh ode\mesh,0,0,0
PositionMesh ode\mesh,0,0,0
EntityColor ode\mesh,40,80,255
EntityAlpha ode\mesh,1

; ### Create wheels

For count=1 To 4
	ode.ODEGeom=New ODEGeom
	ode\body=dBodyCreate(World)
	Wheel(count)=ode\body
	dBodySetRotation(ode\body,0,0,0)
	dBodySetPosition(ode\body,0,0,0)
	mass=dMassCreate()
	dMassSetSphereTotal(mass,WMass,0.7)
	dBodySetMass(ode\body,mass)
	dMassDestroy(mass)
	ode\geom=dCreateSphere(Space,0.7)
	WGeom(count)=ode\geom
	dGeomSetBody(ode\geom,ode\body)
	ode\mesh=CreateCylinder(8)
	ScaleMesh ode\mesh,0.7,0.25,0.7
	RotateMesh ode\mesh,0,0,90
	PositionMesh ode\mesh,0,0,0
	EntityColor ode\mesh,255,255,255
Next

dBodySetPosition(Wheel(1),-2,CarStartY-0.5,+2)
dBodySetPosition(Wheel(2),+2,CarStartY-0.5,+2)
dBodySetPosition(Wheel(3),-2,CarStartY-0.5,-2)
dBodySetPosition(Wheel(4),+2,CarStartY-0.5,-2)

; ### Create light

Global Light=CreateLight()

RotateEntity Light,45,-90,0
LightColor Light,255,255,255
AmbientLight 130,130,130

; ### Create camera

Global CameraPivot=CreatePivot(CMesh)
PositionEntity CameraPivot,0,2,-7

Global Camera=CreateCamera()
CameraClsColor Camera,0,0,0
CameraRange Camera,1,1000

; ### Create plane

dCreatePlane(Space,0,1,0,0)

Plane=CreatePlane()

EntityAlpha Plane,0.8

PlaneTexture=CreateTexture(128,128,9)

ClsColor 0,200,80
Cls

Color 255,255,255

Rect 0,0,64,64,1
Rect 64,64,64,64,1

CopyRect 0,0,128,128,0,0,BackBuffer(),TextureBuffer(PlaneTexture)
ScaleTexture PlaneTexture,20,20
EntityTexture Plane,PlaneTexture,0,0

Mirror=CreateMirror()

; ###################################################################################################

SetupCar()

SetupObjects()

While Not KeyHit(1)

	UpdateKeys()

	PTime=MilliSecs()

	UpdateCar()

	UpdateGeoms()

	dSpaceCollide(Space,World,ContactGroup)
	dWorldQuickStep(World,0.1)
	dJointGroupEmpty(ContactGroup)

	PhysicsTime#=MilliSecs()-PTime

	UpdateCam()

	UpdateWorld

	RenderWorld

	Text 0,0,"JV-ODE Version "+dGetVersion()
	Text 0,15,"Physics Time:"+PhysicsTime
	Text 0,50,"Force:"+Force
	Text 0,65,"Torque:"+Torque
	Text 640,0,"A - Accelerate"
	Text 640,15,"Z - Brake/Reverse"
	Text 640,30,"Arrows - Steering"
	Text 640,45,"Space - Reset Car"

	Flip

Wend

dJointGroupDestroy(ContactGroup)
dSpaceDestroy(Space)
dWorldDestroy(World)
dCloseODE()

End

; ###################################################################################################

Function SetupCar()

For count=1 To 4
	Joint(count)=dJointCreateHinge2(World,0)
	dJointAttach(Joint(count),Car,Wheel(count))
	dJointSetHinge2Anchor(Joint(count),dBodyGetPositionX(Wheel(count)),dBodyGetPositionY(Wheel(count)),dBodyGetPositionZ(Wheel(count)))
	dJointSetHinge2Axis1(Joint(count),0,1,0)
	dJointSetHinge2Axis2(Joint(count),-1,0,0)
	dJointSetHinge2Param(Joint(count),dParamSuspensionERP,0.8)
	dJointSetHinge2Param(Joint(count),dParamSuspensionCFM,SuspensionHS)
	If count>2
		dJointSetHinge2Param(Joint(count),dParamLoStop,0)
		dJointSetHinge2Param(Joint(count),dParamHiStop,0)
		End If
Next

Force=0

End Function

; ###################################################################################################

Function SetupObjects()

For count=1 To 30
	AddObjects((xp*34)-120,17,(zp*34)+100)

	xp=xp+1
	If xp>7
		xp=0
		zp=zp+1
		End If
Next

End Function

; ###################################################################################################

Function AddObjects(objectxp,objectyp,objectzp)

ode.ODEGeom=New ODEGeom
ode\body=dBodyCreate(World)
dBodySetRotation(ode\body,0,0,0)
dBodySetPosition(ode\body,objectxp,objectyp,objectzp)
ode\geom=dCreateSphere(Space,8)
dGeomSetBody(ode\geom,ode\body)

ode\mesh=CreateSphere()
ScaleMesh ode\mesh,8,8,8
RotateMesh ode\mesh,0,0,0
PositionMesh ode\mesh,0,0,0
EntityColor ode\mesh,255,255,255
EntityAlpha ode\mesh,0.8
EntityShininess ode\mesh,0.7

transxp=-7
transyp=0

For count=1 To 3
	GeomObject=dCreateSphere(Space,4)
	dGeomSetBody(GeomObject,ode\body)
	dGeomSetOffsetPosition(GeomObject,transxp,transyp,0)

	GeomMesh=CreateSphere(8,ode\mesh)
	ScaleMesh GeomMesh,4,4,4
	RotateMesh GeomMesh,0,0,0
	PositionMesh GeomMesh,transxp,transyp,0
	EntityColor GeomMesh,count*10,count*70,255
	EntityAlpha GeomMesh,1
	EntityShininess GeomMesh,0.7

	If count=2
		transxp=0
		transyp=-7
		Else
		transxp=transxp+14
		End If
Next

End Function

; ###################################################################################################

Function UpdateKeys()

If KeyDown(30)=1
	Force=Force+0.08
	If Force>30 Then Force=30
	End If

If KeyDown(44)=1
	Force=Force-0.1
	If Force<-10 Then Force=-10
	If Force>0 Then Force=Force*0.97
	End If

If KeyDown(30)=0 And KeyDown(44)=0 Then Force=Force*0.99

If KeyDown(203)=1 Or KeyDown(205)=1
	If KeyDown(203)=1
		Steer=0.5
		Else
		Steer=-0.5
		End If
	Else
	Steer=0
	End If

If KeyHit(57)=1
	Force=0
	dBodySetRotation(Car,dGeomGetPitch#(CGeom),dGeomGetYaw#(CGeom),0)
	End If

End Function

; ###################################################################################################

Function UpdateCar()

For count=1 To 4
	dBodyEnable(Wheel(count))
Next

dBodyEnable(Car)

For count=1 To 4
	dJointSetHinge2Param(Joint(count),dParamVel2,Force)
	dJointSetHinge2Param(Joint(count),dParamFMax2,Torque)
Next

For count=1 To 2
	angle#=Steer-dJointGetHinge2Angle1(Joint(count))
	dJointSetHinge2Param(Joint(count),dParamVel,angle)
	dJointSetHinge2Param(Joint(count),dParamFMax,400)
Next

End Function

; ###################################################################################################

Function UpdateCam()

PositionEntity CameraPivot,0,3,-10

camx#=EntityX(CameraPivot,1)-EntityX(Camera)
camy#=EntityY(CameraPivot,1)-EntityY(Camera)
camz#=EntityZ(CameraPivot,1)-EntityZ(Camera)

TranslateEntity Camera,camx*0.5,camy*0.5,camz*0.5

PointEntity Camera,CMesh

End Function

; ###################################################################################################

Function UpdateGeoms()

For ode.ODEGeom=Each ODEGeom
	RotateEntity ode\mesh,dGeomGetPitch#(ode\geom),dGeomGetYaw#(ode\geom),dGeomGetRoll#(ode\geom)
	PositionEntity ode\mesh,dGeomGetPositionX#(ode\geom),dGeomGetPositionY#(ode\geom),dGeomGetPositionZ#(ode\geom)
Next

End Function

; ###################################################################################################

Hmmm... interesting.. I tried using the dGeomSetOffsetPosition functions before but for some reason that didn't work as simple as you show in these demos. I obviously must have done something wrong..
I just spend 2 hours last weekend bypassing that geomTransform memoryleak stuff we talked about before :)
Anyway, I'm happy to see that these Offset functions DO work - and should only take a jiffy to implement as opposed to how I got things now :)

I got to check this, but I assume you'd still have to destroy every geometry you create - as opposed to 'just the body' they're attached to....

Cheers dude!

danny.

You're welcome :)

Yep, you will need to destroy every geom created to clean up correctly. Destroying the body only will not destroy the associated geoms, the geoms would become static objects unless they're also destroyed.

ok, first noob question, is there no "dCreateCone()" function?? If not, is there any other way to use a cone shape?

John

There's no cone geometry in ODE unfortunately. The easiest way to use a cone shape would be to create a cone mesh in a 3D mesh editor and save it as .b3d or .3ds etc. Then you can use it to create a TriMesh in ODE. You need to keep in mind that moving TriMeshes are not as fast as static TriMeshes.

If you look at the 'Demo-TriMeshes' demo, you can see that any geometry shape can be used if they're not natively provided within ODE. It just means that you would have to build the mesh in an editor and create a TriMesh from it.

There may be other solutions available, but I'd need more detail on how you would like to use the cones.

Hope this helps ;)

Thank you,

I've got it sorted now (almost). I made a trimesh using a blitz cone. Just wanted to add a cone the falling shapes demo.

Might have a go at ragdolls over the weekend. There's a few things I want to try out like clicking and dragging objects. Will let you know how I get on ;o)

More questions to come...

Could someone please explain to me what a "ray" is and how it is used?

A ray is an infinitely thin line in 3D space.

You can use it for pin point physics responses like forces from a bullet hitting a target.

Or, you can use it for line picking (same as Blitz3D line pick stuff). To do this without a physics response you will need to process the collisions without stepping the simulation.

Thanks VIP3R ;o)

I'm trying to do chain physics now, based on the example. I want to be able to make any number of chains so I'm putting the arrays for the chain links and joints into the ODE type. When I make the chain now, it's rigid and won't move. Any ideas?

EDIT

Removed code, got it working now :o)

[Reposted From Blitz3D Thread]

Kestrel (Posted 22 hours ago) Edit

Hi,
I was doing some tinkering with the Demo's for JV-ODE (With Blitz 3D 1.98), specifically Spheres, which just repeatedly drops spheres onto a plane and I get a Stack Overflow from Blitz after increasing the drop rate when I get to about 1500 objects.
I realize that my frame computation time at this stage is high and usefulness of 1500 balls rolling around a plane had limited uses (=P), but my RAM was far from exhausted and I would have anticipated that this would have been the sole restriction for this type of activity.
Is this expected behaviour, can the stack be increased, or it the demo doing something functionally recursive (apart from adding another ball to a list)?

Thanks =)



Wayne (Posted 21 hours ago)

I would expect that to happen.
I believe one could recompile with a larger stack, but as you pointed out it would be of little practical use.



Kestrel (Posted 21 hours ago) Edit

Ok,
I was looking at doing some 'many thousand object' experiments and just playing it back after computation even if each frame took several minutes.
I wonder if it would be possible to get the stack size as a command line argument (that defaults to current value) that was dynamically allocated so you could fully utilize your machine with more objects if you chose?



VIP3R (Posted 2 hours ago)

The problem you are experiencing is due to creating too many objects which are inside each others collision zone. It would also cause horrendous slow down.

To stop the Stack Overflow occurring you need to make sure they don't overlap during creation.

Btw, this should be in the JV-ODE threads really as it's not a Blitz3D issue ;)


JV-ODE Physics V1.20 - Official JV-ODE Threads: 1 2 3 4 5 6 7 8 - Available for Blitz3D & BlitzMax (Win32)
Specs: WinXP SP2 - Pentium 4 2.7GHz - ATI Radeon 9800 128DDR - DirectX 9.0c - 1GB DDR RAM


Kestrel (Posted 5 seconds ago) Edit

Thanks VIP3R,
I wasn't sure if it would be a JV-ODE issue as I figured it just wrapped the ODE library and there would be no reason there would be a limit the amount of objects, you're simply constrained by your own resources.
From what I see of the code, aren't the object already created in such a way that they don't overlap upon creation, i.e. X,Y = Rand(-8 to 8)? From what you said, I guess that would mean I could create 10,000 even spaced spheres for example and they would sit on a plane quite happily (this is not the restriction), but if I put a wall around them all and rolled them into one corner, the system would start to fall over once the collision zone intercepts became bigger than the stack could handle?
I realize the horrendous slowdown, but that is acceptable for what I'm doing. Any way I'll have to delve deeper in to the documentation of how the collision detection (zones) work.

Thanks for the feedback. =)

[I'll Repost this in a JV-ODE Thread]

You're correct, the objects are created within a small area of 16 units square (-8 to 8). There's more to it than that though, firstly there's the timer... If MilliSecs()-Timer>700 and secondly there's gravity. The timer is there to allow the objects to fall by gravity to a safe distance before the next object is added, increasing the rate as you did will not allow enough time for the objects to drop before the next is created thus causing the collision overlap and the overflow.

You could change the creation location by adding a much larger random coordinate area... X and Z = Rand(-2000,2000), then whatever timer rate you use it should be ok, if not increase the random area values accordingly.

That makes sense, Thanks VIP3R. I'll keep fiddling =P

Hi Vip3r,

I still have somewhat of a struggle when it comes to offsetting geometry. Do you have any inside knowledge of how ODE responds when the FIRST (ie. the 'main') geometry is off-set in relation to the rigidbody?

You demo's above illustrate that geom offsetting works fine. But, in those demos you create a 'first' geometry (that also acts to position the ode\mesh's later) and ONLY offset the following additional geometries.

When I offset the first geom, the rigid body behaves and moves around very unpredictably! It's not just as-if the body's Center of Gravity has moved, but on occasion the body starts moving, roling and bouncing around by itself as well. Good trick if you're looking to study the internal dynamics behind mexican jumping beans; But otherwise pretty useless for what I'm trying to do :)

For example, say you model a wine glass. In that case i want to model the bottom of the glass at 0,0,0 - makes more sense and easier to handle when placing, etc. But this means the center of gravity (or the center of the mesh) is NOT at 0,0,0 but a couple centimeters above it, so I need to offset my first and only geometry for that model...

Any insights -as always- appreciated!

Danny
p.s. I can come up with several workaround to this problem, so not a massive problem. I'd just like to understand what it's doing ;)

It doesn't make any difference if you use only one geom and offset it. The only demo which would be suitable to show this would be the GeomOffset-Car demo. It currently uses two geoms for a direct comparison to the GeomTransform-Car demo, but the final version to be released with a future update will only use one geom which is offset.

Wherever you create the body of the ODE object will be the center of gravity, adding one geom and offsetting it will have the exact same effect as moving the center of gravity, but the center of gravity will still be at the location of the body, not the geom.

Here's a version of the GeomOffset-Car demo which uses only one geom offset from the body...

; ###################################################################################################
; #										  JV-ODE Car Demo											#
; #									Code by Jim Williams (VIP3R)									#
; #								Devious Codeworks - Copyright © 2006								#
; ###################################################################################################

AppTitle "JV-ODE Car Demo - Geom Offset - Car"

Include "JV-ODE.bb"

Graphics3D 800,600,0,2

Global CMass#=200			; ### Car Mass
Global WMass#=14			; ### Wheel Mass

Global WorldERP#=1			; ### World Error Correction
Global WorldFriction#=140	; ### World Friction

Global Torque#=24			; ### Joint Torque
Global SuspensionHS#=0.01	; ### Suspension Hardness/Softness (Higher=Softer - Lower=Harder)

Global Force#=0
Global Steer#=0

Global Car
Global CGeom
Global CMesh

Global CarStartY=20

Dim Wheel(4)
Dim WGeom(4)
Dim Joint(4)

Type ODEGeom
	Field body
	Field geom
	Field mesh
End Type

; ###################################################################################################

; ### Setup ODE

Global World=dWorldCreate()
Global Space=dHashSpaceCreate(0)
Global ContactGroup=dJointGroupCreate(0)

dWorldSetAutoDisableFlag(World,1)
dWorldSetGravity(World,0,-0.98,0)
dWorldSetERP(World,WorldERP)

dContactSetMode(dContactSlip1)
dContactSetMu(WorldFriction)

; ### Create car body

ode.ODEGeom=New ODEGeom
ode\body=dBodyCreate(World)
Car=ode\body
dBodySetRotation(ode\body,0,0,0)
dBodySetPosition(ode\body,0,CarStartY-1,0)
mass=dMassCreate()
dMassSetBoxTotal(mass,CMass,3,1,4)
dBodySetMass(ode\body,mass)
dMassDestroy(mass)
ode\geom=dCreateBox(Space,3,1,4)
CGeom=ode\geom
dGeomSetBody(ode\geom,ode\body)
dGeomSetOffsetPosition(ode\geom,0,1,0)
ode\mesh=CreateCube()
CMesh=ode\mesh
ScaleMesh ode\mesh,1.5,0.5,2
RotateMesh ode\mesh,0,0,0
PositionMesh ode\mesh,0,0,0
EntityColor ode\mesh,40,80,255
EntityAlpha ode\mesh,0.7

BodyPosition=CreateCube(ode\mesh)
ScaleMesh BodyPosition,1.5,0.5,2
RotateMesh BodyPosition,0,0,0
PositionMesh BodyPosition,0,-1,0
EntityColor BodyPosition,255,40,80
EntityAlpha BodyPosition,0.4
EntityShininess BodyPosition,0.7

; ### Create wheels

For count=1 To 4
	ode.ODEGeom=New ODEGeom
	ode\body=dBodyCreate(World)
	Wheel(count)=ode\body
	dBodySetRotation(ode\body,0,0,0)
	dBodySetPosition(ode\body,0,0,0)
	mass=dMassCreate()
	dMassSetSphereTotal(mass,WMass,0.7)
	dBodySetMass(ode\body,mass)
	dMassDestroy(mass)
	ode\geom=dCreateSphere(Space,0.7)
	WGeom(count)=ode\geom
	dGeomSetBody(ode\geom,ode\body)
	ode\mesh=CreateCylinder(8)
	ScaleMesh ode\mesh,0.7,0.25,0.7
	RotateMesh ode\mesh,0,0,90
	PositionMesh ode\mesh,0,0,0
	EntityColor ode\mesh,255,255,255
Next

dBodySetPosition(Wheel(1),-2,CarStartY-0.5,+2)
dBodySetPosition(Wheel(2),+2,CarStartY-0.5,+2)
dBodySetPosition(Wheel(3),-2,CarStartY-0.5,-2)
dBodySetPosition(Wheel(4),+2,CarStartY-0.5,-2)

; ### Create some objects

SeedRnd MilliSecs()

For spheres=1 To 20
	ode.ODEGeom=New ODEGeom
	ode\body=dBodyCreate(World)
	dBodySetRotation(ode\body,0,0,0)
	dBodySetPosition(ode\body,Rnd(-100,100),30,Rnd(-100,100))
	ode\geom=dCreateSphere(Space,4)
	dGeomSetBody(ode\geom,ode\body)
	ode\mesh=CreateSphere()
	ScaleMesh ode\mesh,4,4,4
	RotateMesh ode\mesh,0,0,0
	PositionMesh ode\mesh,0,0,0
	EntityColor ode\mesh,Rnd(255),Rnd(255),Rnd(255)
	EntityAlpha ode\mesh,1
	EntityShininess ode\mesh,0.7
Next

For capsules=1 To 20
	ode.ODEGeom=New ODEGeom
	ode\body=dBodyCreate(World)
	dBodySetRotation(ode\body,90,0,0)
	dBodySetPosition(ode\body,Rnd(-100,100),30,Rnd(-100,100))
	ode\geom=dCreateCapsule(Space,1,8)
	dGeomSetBody(ode\geom,ode\body)
	ode\mesh=CreateCylinder(8)
	ScaleMesh ode\mesh,1,5,1
	RotateMesh ode\mesh,90,0,0	; <<< Mesh X-Axis must be rotated 90 degrees to fix cylinder alignment
	PositionMesh ode\mesh,0,0,0
	EntityColor ode\mesh,Rnd(255),Rnd(255),Rnd(255)
	EntityAlpha ode\mesh,1
	EntityShininess ode\mesh,0.7
Next

; ### Create light

Global Light=CreateLight()

RotateEntity Light,45,-90,0
LightColor Light,255,255,255
AmbientLight 130,130,130

; ### Create camera

Global CameraPivot=CreatePivot(CMesh)
PositionEntity CameraPivot,0,2,-7

Global Camera=CreateCamera()
CameraClsColor Camera,0,0,0
CameraRange Camera,1,1000

; ### Create plane

dCreatePlane(Space,0,1,0,0)

Plane=CreatePlane()

EntityAlpha Plane,0.8

PlaneTexture=CreateTexture(128,128,9)

ClsColor 0,200,80
Cls

Color 255,255,255

Rect 0,0,64,64,1
Rect 64,64,64,64,1

CopyRect 0,0,128,128,0,0,BackBuffer(),TextureBuffer(PlaneTexture)
ScaleTexture PlaneTexture,20,20
EntityTexture Plane,PlaneTexture,0,0

Mirror=CreateMirror()

; ###################################################################################################

; ### BLITZ STATIC OBJECT (White)

blitzobject=CreateCube()
ScaleMesh blitzobject,1,4,20
RotateMesh blitzobject,-10,8,4
PositionMesh blitzobject,10,5,40

EntityColor blitzobject,255,255,255
EntityAlpha blitzobject,1

; ### ODE STATIC OBJECT (Blue)

ode.ODEGeom=New ODEGeom
ode\geom=dCreateBox(Space,2,8,40)
dGeomSetRotation(ode\geom,-10,8,4)
dGeomSetPosition(ode\geom,20,5,40)
ode\mesh=CreateCube()
ScaleMesh ode\mesh,1,4,20
RotateMesh ode\mesh,0,0,0
PositionMesh ode\mesh,0,0,0

EntityColor ode\mesh,0,100,200
EntityAlpha ode\mesh,1

; ### ODE STATIC OBJECT (Red)

ode.ODEGeom=New ODEGeom
ode\geom=dCreateBox(Space,18,0.2,40)
dGeomSetRotation(ode\geom,-14,0,0)
dGeomSetPosition(ode\geom,-20,4.9,40)
ode\mesh=CreateCube()
ScaleMesh ode\mesh,9,0.1,20
RotateMesh ode\mesh,0,0,0
PositionMesh ode\mesh,0,0,0

EntityColor ode\mesh,200,0,100
EntityAlpha ode\mesh,1

; ###################################################################################################

SetupCar()

While Not KeyHit(1)

	UpdateKeys()

	PTime=MilliSecs()

	UpdateCar()

	UpdateGeoms()

	dSpaceCollide(Space,World,ContactGroup)
	dWorldQuickStep(World,0.1)
	dJointGroupEmpty(ContactGroup)

	PhysicsTime#=MilliSecs()-PTime

	UpdateCam()

	UpdateWorld

	RenderWorld

	Text 0,0,"JV-ODE Version "+dGetVersion()
	Text 0,15,"Physics Time:"+PhysicsTime
	Text 0,50,"Force:"+Force
	Text 0,65,"Torque:"+Torque
	Text 0,100,"Blue = Geom Offset"
	Text 0,115,"Red = Body/Mass Position"
	Text 640,0,"A - Accelerate"
	Text 640,15,"Z - Brake/Reverse"
	Text 640,30,"Arrows - Steering"
	Text 640,45,"Space - Reset Car"

	Flip

Wend

dJointGroupDestroy(ContactGroup)
dSpaceDestroy(Space)
dWorldDestroy(World)
dCloseODE()

End

; ###################################################################################################

Function SetupCar()

For count=1 To 4
	Joint(count)=dJointCreateHinge2(World,0)
	dJointAttach(Joint(count),Car,Wheel(count))
	dJointSetHinge2Anchor(Joint(count),dBodyGetPositionX(Wheel(count)),dBodyGetPositionY(Wheel(count)),dBodyGetPositionZ(Wheel(count)))
	dJointSetHinge2Axis1(Joint(count),0,1,0)
	dJointSetHinge2Axis2(Joint(count),-1,0,0)
	dJointSetHinge2Param(Joint(count),dParamSuspensionERP,0.8)
	dJointSetHinge2Param(Joint(count),dParamSuspensionCFM,SuspensionHS)
	If count>2
		dJointSetHinge2Param(Joint(count),dParamLoStop,0)
		dJointSetHinge2Param(Joint(count),dParamHiStop,0)
		End If
Next

Force=0

End Function

; ###################################################################################################

Function UpdateKeys()

If KeyDown(30)=1
	Force=Force+0.08
	If Force>30 Then Force=30
	End If

If KeyDown(44)=1
	Force=Force-0.1
	If Force<-10 Then Force=-10
	If Force>0 Then Force=Force*0.97
	End If

If KeyDown(30)=0 And KeyDown(44)=0 Then Force=Force*0.99

If KeyDown(203)=1 Or KeyDown(205)=1
	If KeyDown(203)=1
		Steer=0.5
		Else
		Steer=-0.5
		End If
	Else
	Steer=0
	End If

If KeyHit(57)=1
	Force=0
	dBodySetRotation(Car,dGeomGetPitch#(CGeom),dGeomGetYaw#(CGeom),0)
	End If

End Function

; ###################################################################################################

Function UpdateCar()

For count=1 To 4
	dBodyEnable(Wheel(count))
Next

dBodyEnable(Car)

For count=1 To 4
	dJointSetHinge2Param(Joint(count),dParamVel2,Force)
	dJointSetHinge2Param(Joint(count),dParamFMax2,Torque)
Next

For count=1 To 2
	angle#=Steer-dJointGetHinge2Angle1(Joint(count))
	dJointSetHinge2Param(Joint(count),dParamVel,angle)
	dJointSetHinge2Param(Joint(count),dParamFMax,400)
Next

End Function

; ###################################################################################################

Function UpdateCam()

PositionEntity CameraPivot,0,3,-12

camx#=EntityX(CameraPivot,1)-EntityX(Camera)
camy#=EntityY(CameraPivot,1)-EntityY(Camera)
camz#=EntityZ(CameraPivot,1)-EntityZ(Camera)

TranslateEntity Camera,camx*0.5,camy*0.5,camz*0.5

PointEntity Camera,CMesh

End Function

; ###################################################################################################

Function UpdateGeoms()

For ode.ODEGeom=Each ODEGeom
	RotateEntity ode\mesh,dGeomGetPitch#(ode\geom),dGeomGetYaw#(ode\geom),dGeomGetRoll#(ode\geom)
	PositionEntity ode\mesh,dGeomGetPositionX#(ode\geom),dGeomGetPositionY#(ode\geom),dGeomGetPositionZ#(ode\geom)
Next

End Function

; ###################################################################################################

As you can see the demo works exactly as expected, if you're experiencing strange effects it's very likely that you're doing something wrong somewhere.

Try changing the following two lines in the above demo...

dGeomSetOffsetPosition(ode\geom,0,1,0)
...
PositionMesh BodyPosition,0,-1,0

to

dGeomSetOffsetPosition(ode\geom,0,10,0)
...
PositionMesh BodyPosition,0,-10,0

Now you will see the position of the geom has been offset much higher, but the center of gravity (and the body/mass) still remains at its original location. You can test this by trying to overturn the car.

And no mexican jumping bean syndrome to be seen at all ;)

Are you using any mass? Zero mass could cause odd effects.