2d Polygon collision Module

This is a Polygon Collision module that uses code written by Gosse Corrupted (ported from Blitz to BlitzMax)

Unzip the attached files to your "BlitzMax Directory\mod\"

There is a demo in the zip file.

http://www.indiepath.com/tim/indiepath.mod.zip

you know, I really need line collision as I am doing a platform game, so this will be a great help I think.

However I placed the mod in blitzmax\mods and tried the demo but it wouldn't work

Skunk, What error is BMAx giving you?

i have an error, too:

[ERROR]: Compile Error:Can't find interface for module 'indiepath.poly'

(using protean for blitzmax)

Does your path look something like this?

Blitzmax\mod\indiepath.mod\poly.mod

I've uploaded a new file which might work :)

sniff, still the same error. i double checked the paths etc. but it didn't help...

I am now confused. I can only replecate your error if I move the files elsewhere.

Have you had any problems with other Modules?

Simply put the directory "indiepath.mod" in the mod folder of Bmax.

Nice work! ;)

Yeah, someone got it working.. and they did exactly what I originally said ?!?!

I get this error:It compiles fine, but the example crashes.

Ouch, that looks to me like a problem with types. But why does it run okay for me, Extron and others that have tested it for me.???

Source is now posted in the zip file, perhaps someone can work out the problem and let me know.

Well, i clarify my previous post. :)

Simply put the directory "indiepath.mod" in the mod folder of Bmax and compile run "testpoly.bmx" in this folder ("indiepath.mod").

Is this work?

Rebuilding the module did the trick. Don't know why it didn't work before.

Yes, i've don't mention this. :)

Very odd, perhaps that is why we are still in Beta. :)

Also. :)

Perhaps you compiled the module in debug mode but the example code in release mode or vice versa?

Here is the error I get:

Compiling:testpoly.bmx
Linking:testpoly.debug
ld: archive: /Users/stephen/Applications/Development/Languages/BlitzMax/BlitzMax024/mod/indiepath.mod/poly.mod/poly.d.a has no table of contents, add one with ranlib(1) (can't load from it)
Build Error: Failed to link /Users/stephen/Applications/Development/Languages/BlitzMax/BlitzMax024/testpoly.debug.app/Contents/MacOS/testpoly.debug

Will try "build modules."

Building modules fixed it. Duh. Works wonderfully. Actually, I had already implemented most of that code myself but never released it :) Or, more accurately, I implemented a point-line distance algorithm that makes collision detection dead easy. Will post in the future, but I don't want to spend my time writing mods, I want to spend my time writing games.

I improved the code a little (atleast to my liking) I made methods out of the functions. Which made the implentation much more trival (easier).
Ex instead of :

ship:dPoly = dPoly.Create()
dPoly.Poly_AddVertex(ship,0,-5)
dPoly.Poly_Resize(ship,10,10)
ship1:dPoly = dPoly.Poly_Copy(ship)

You would Do:
Ship:Polygon = Polygon.Create()
Ship.AddVertex(0,-5)
Ship.Resize(10,10)
Ship2:Polygon = Ship.Copy()

It helps me to speed up the coding =)

I also added a example line infront of each function

And I made a new example to test the Polygon-Type. Even thou I do not use it as a module here below just un-comment the import part and make sure you name everything correctly and it should still work as a stand alone module.

Strict

'TO TEST RUN
Graphics 800,600,0',300'16,500

Global Poly1:TPolygon = TPolygon.Create()
'This creates a box with size 100x100
Poly1.Add(-50,-50)
Poly1.Add(50,-50)
Poly1.Add(50,50)
Poly1.Add(-50,50)
Poly1.Add(-50,-50)
Global Poly2:TPolygon = Poly1.Copy()
Global Rect:TPolygon  = Poly1.Copy()

Global X,Y 'This is for the test ball
Global GW = GraphicsWidth()/2 , GH = GraphicsHeight()/2 'Center everything so that we look from the coordinates 0,0 in the middle

Local Fps:FpsCounter = New FPSCounter
While Not KeyDown(Key_Escape)

	If Poly1 And Poly2
	
		If KeyHit(1) Poly1.Add( MouseX()-GW,MouseY()-GH )	'LeftMouse
		
		If KeyHit(2) Poly1.Add( Poly1.ix[0],Poly1.iy[0] )'Join back to start 'Right Mouse
		
		If KeyHit(Key_Space) Poly1 = TPolygon.Create() 'Start on a new Polygon
		
		Plot MouseX(),MouseY()	 'Mark Mouse

		Poly1.Draw( GW,GH )
		
		Poly2.Remove()
		Poly2 = Poly1.Copy() 'Make a copy of the polygon
		Poly2.Scale( 0.1 , 0.1 )'10% smaller
		Poly2.Draw( MouseX(), MouseY() )
		
		If PolygonOverlap(Poly1,GW,GH,Poly2,MouseX(), MouseY() ,False )
			DrawText "< <   C O L L I S I O N   D E T E C T E D   > >" , 0,0
		EndIf
		
		If PolygonOverlap(Poly1,GW,GH,Rect,X,Y,False )
			DrawText "< <   C O L L I S I O N   D E T E C T E D   > >" , 2,0
		EndIf	
			
		If PolygonOverlap(Poly2,MouseX(),MouseY(),Rect,X,Y,False )
			DrawText "< <   C O L L I S I O N   D E T E C T E D   > >" , 0,2
		EndIf		

	EndIf

		Rect.Draw(X,Y) ; X:+Rand(-2,2) ;Y:+Rand(-1,1)'Draw and shake the ball		
		
		DrawText( "X: "+MouseX()+"  Y: "+MouseY(),20,20 ) 
		FPS.CalculateFPS() ;FPS.DrawFPS(20,40)
		
		If KeyDown(Key_D) Poly1 = Null ;Poly2 = Null
		DrawText( " Polygon Count : "+Tpolygon.Count,20,60 )
			
Flip;Cls	
Wend


Type FPSCounter
	Field FPS%,Count%,Time%
	
	Method CalculateFPS()
			Count:+1			
			If Time+1000 < MilliSecs() 'FPS last sec
				
				FPS=Count' <- Frames/Sec
				Count=0
				Time=MilliSecs()			
			EndIf	
	End Method
	
	Method DrawFPS(X=0,Y=0)
		DrawText "Current FPS: "+FPS,X,Y
	End Method
	
	Method New() Time = MilliSecs() EndMethod
End Type
'---------------------------------------------------------------------------------------




Rem
Here starts the actuall module 

Module indiepath.poly

ModuleInfo "Name: 2d Polygon Lib"
ModuleInfo "License: Public Domain"
ModuleInfo "Author: Tim Fisher & Gosse Corrupted , Edit by Wave"

Import BRL.LinkedList
Import BRL.GLMax2D
End Rem


Global gSin#[360]
Global gCos#[360]

Local a%

For a = 0 To 359
	gSin#[a] = Sin(a)
	gCos#[a] = Cos(a)
Next

Type TPolygon
	
	Global List:TList
	Global Count
		
	Field iX#[64]	
	Field iY#[64]	
	Field fX#[64]	
	Field fY#[64]	
	Field iVertexCount		
	Field fScaleX#			
	Field fScaleY#			
	Field fAngle#			
	Field iMinX#				
	Field iMinY#				
	Field iMaxX#				
	Field iMaxY#
				
		'Used internally only
		Method New ()
            	If List = Null Then List = CreateList()
            	List.AddLast Self
			Count:+1
    		End Method		
		
		Method Remove()            	
			List.Remove Self
			Count:-1	
		EndMethod
		'Remove this Poly
		'MyPoly.Remove
		
		'Create a New Polygon Instance		
		'MyPoly:Polygon = Polygon.Create()
		Function Create:Tpolygon()
			Local Poly:TPolygon
			Poly = New TPolygon
			Poly.fScaleX=1;Poly.fScaleY=1
			Return Poly
		End Function		
		
		' The use:
		' MyPoly.AddVertex(x,y)
		Method AddVertex( X#,Y#, Update=True)
			iX#[iVertexCount] = x#
			iY#[iVertexCount] = y#		
			iVertexCount:+ 1
			If Update Then Self.Update()
		End Method
		'This is a even shorter version =)
		Method Add(X#,Y#,Update=True)
			AddVertex(X,Y,Update=True)		
		EndMethod
				
				
		'Scale alters the size
		'Ex to scale to double size
		'MyPoly.Scale(2,2)' 2 = 200%
		'Ex to scale to half size
		'MyPoly.Scale(0.5,0.5)' 0.5 = 50%
		Method Scale(sx#,sy#,Update=True)
			fScaleX#:* sx#
			fScaleY#:* sy#	
			If Update Then Self.Update()
		EndMethod

		
		'Resize the Poly by a stated amount
		'Set the polygon size		
		'MyPoly.ReSize(1,1)'set to original size
		Method Resize(sx#,sy#,update=True)
			fScaleX# = sx#
			fScaleY# = sy#	
			If update Then Self.Update()
		EndMethod
		
		
		'Turn the Poly By the stated amount
		'Ex MyPoly.Turn(15) 
		'Adds to the current direction
		Method Turn(rot#,update=True)
			fAngle# = wrap_angle(fAngle# + rot#)
			If update Then Self.Update()
		EndMethod
		
		
		'Rotate the Poly by the stated amount
		'Set the direction to this angle
		Method SetDir(Angle#,update=True)
			fAngle# = wrap_angle(angle#)
			If update Then Self.Update()
		EndMethod
		
		

		
		'Copy one poly to another
		'Returns a Polygon equal to the one you copied
		'Ex:
		'ACopyofMyPoly:Polygon = MyPoly.Copy()
		Method Copy:TPolygon()
			Local NewPoly:TPolygon
			NewPoly = New TPolygon
				
			For Local i = 0 To iVertexCount - 1
				NewPoly.iX#[i] = iX#[i]
				NewPoly.iY#[i] = iY#[i]
				NewPoly.fX#[i] = fX#[i]
				NewPoly.fY#[i] = fY#[i]
			Next
			
			NewPoly.iVertexCount = iVertexCount
			NewPoly.fScaleX#	= fScaleX#
			NewPoly.fScaleY#	= fScaleY#
			NewPoly.fAngle# 	= fAngle#
			NewPoly.iMinX# 	= iMinX#
			NewPoly.iMinY#	= iMinY#
			NewPoly.iMaxX# 	= iMaxX#
			NewPoly.iMaxY# 	= iMaxY#
			
			Return NewPoly
		EndMethod
		
		
		
		'Update the Poly
		Method Update()
			Local f1X#, f1Y#, f1#, f2#, angle#,i 
			
			iMinX = 9999999.00
			iMinY = 9999999.00
			iMaxX = -9999999.00
			iMaxY = -9999999.00
			
			For i = 0 To iVertexCount - 1
				f1X# = iX#[i] * fScaleX#
				f1y# = iY#[i] * fScaleY#
				
				angle# = fAngle#
				
				If angle# <> 0 Then
					f1# = gCos#[Angle#] * f1X# - gSin#[Angle#] * f1Y#
					f2# = gSin#[Angle#] * f1X# + gCos#[Angle#] * f1Y#
					f1X# = f1#
					f1y# = f2#
				EndIf
		
				fX#[i] = f1X#
				fY#[i] = f1Y#
					
				If f1X# < iMinX# Then iMinX = f1X#
				If f1Y# < iMinY# Then iMinY = f1Y#
				If f1X# > iMaxX# Then iMaxX = f1X#
				If f1Y# > iMaxY# Then iMaxY = f1Y#
			Next
		End Method			

		'Draw the Specified Poly to Screen
		'Uses the current drawing color
		'Dunno what happens with rotations and line-scales?
		Method Draw(x#,y#)
			Local lx#, ly#, i
			lx# = fX#[0] + x#
			ly# = fY#[0] + y#
			
			For i = 1 To iVertexCount -1
				DrawLine (lx#,ly#,fX#[i]+x,fY#[i]+y)
				lx# = fX#[i] + x#
				ly# = fY#[i] + y#
			Next
		EndMethod 
		
		'Make sure all angles are within 0 to 360 degrees
		Function Wrap_Angle#(angle#)
			While angle# >= 360 ; angle#:- 360 ; Wend
			While angle# <  0   ; angle#:+ 360 ; Wend
			Return angle#
		End Function
End Type
	
'Return TRUE if circles overlap
'This is faster than poly overlap and could be used 
'until we get into a "critical" range.
Function CircleOverlap(x1#,y1#,rad1#,x2#,y2#,rad2#)
	Local dx#, dy#, rsqr#
	dx# = x2# - x1#
	dy# = y2# - y1#
	rsqr# = (rad1# + rad2#) * (rad1# + rad2#)
	Return (dx#*dx#+dy#*dy# < rsqr#)
End Function
		
'Checks 2 polygons and sees if they overlap			
Function PolygonOverlap(poly1:TPolygon,x1#,y1#,poly2:TPolygon,x2#,y2#,bounding = True)

	Local tx1#, ty1#, tx2#, ty2#, tx3#, ty3#, tx4#, ty4#
	Local dSqr#, d1#, d2#, dx#, dy#
	Local lx1#, ly1#, lx2#, ly2#
	Local i,j
	
		If bounding Then
			tx1 = X1 + poly1.iMinX
			ty1 = Y1 + poly1.iMinY
			tx2 = X1 + poly1.iMaxX
			ty2 = Y1 + poly1.iMaxY
			tx3 = X2 + poly2.iMinX
			ty3 = Y2 + poly2.iMinY
			tx4 = X2 + poly2.iMaxX
			ty4 = Y2 + poly2.iMaxX
	

			If Not (tx3 > tx1 And ty3 > ty1 And tx3 < tx2 And ty3 < ty2) Then
				If Not (tx4 > tx1 And ty4 > ty1 And tx4 < tx2 And ty4 < ty2) Then
					If Not (tx3 > tx1 And ty4 > ty1 And tx3 < tx2 And ty4 < ty2) Then
						If Not (tx4 > tx1 And ty3 > ty1 And tx4 < tx2 And ty3 < ty2) Then
							Return False
						End If
					End If
				End If
			End If
		End If
		

		lx1 = poly1.fX#[0] + X1
		ly1 = poly1.fY#[0] + Y1
		lx2 = poly2.fX#[0] + X2
		ly2 = poly2.fY#[0] + Y2

		For i = 1 To poly1.iVertexCount - 1
			For j = 1 To poly2.iVertexCount - 1

			tx1 = poly1.fX#[i] + X1
			ty1 = poly1.fY#[i] + Y1
			tx3 = poly2.fX#[j] + X2
			ty3 = poly2.fY#[j] + Y2
			tx2 = lX1
			ty2 = lY1
			tx4 = lX2
			ty4 = lY2

			dSqr = (ty4-ty3)*(tx2-tx1)-(tx4-tx3)*(ty2-ty1)
			d1 = (ty1-ty3)
			d2 = (tx1-tx3)
			dX = ((tx2-tx1)*d1-(ty2-ty1)*d2)
			dY = ((tx4-tx3)*d1-(ty4-ty3)*d2)
	
			If dSqr = 0 Then
	
				If dX = 0 And dY = 0 Then
					Return True
				End If
			Else
	
				d1 = dX / dSqr
				d2 = dY / dSqr
				If (d1 >= 0 And d1 <= 1) And (d2 >= 0 And d2 <= 1) Then
					Return True
				End If
			End If

			lX2 = tx3
			lY2 = ty3
		Next

		lX1 = tx1
		lY1 = ty1
	Next
	Return False
End Function

There isn't someone who would know how to implend collision for points/rects/ovals versus Polygons?

Hi wave,

I've done some improvements at this end also. I've implemented a point in poly detection mode as well as included polygon Collision hulls for detection. And to make it easier I've also coded a polygon editor tool to make your own polys and design the collision hull.

I will post as soon after I release the game I am using it for. aHem, When Win32 Bmax is in release more to the point.

Oh and nice use of the Methods, the code I posted was my first use of BMAX, thanks for the tips :)

Cool! I'm going to use poly-collision for the maps in my game. The plan so far is to use a nice background image of a arena/map and then I'm to use polygons to plot the impasseble terrain and walls from that image. It that way I hope to mix speed with color. A polygon editor would be super!

I just have to ask, What is Collision Hulls? It seems really cool but I have no real idea of what it is or what it does. =) (polygons which are joined?)

Perhaps we should meld our versions, it's public domain anyway =) , What do you think?

Hi Wave,

In the game I am developing the polygons are very complex and the collision algo in the code above would be erroneous. A collision hull is a simple polygonal representation of the complex poly. I use the Hull to check for collisions which is much faster as it has fewer points to check and is a true convex polygon.

Here is a screenie of an early version of the editor to demonstrate. The Blue Lines are the collision hull.

does this only work if the user can compile it?

@John, I don't understand the question. This is blitzmax and it's already compiled into a module

As I see this up...
Looks like the Overlap function don't work as it suposed to work couse if one of the polies it's biger and fits the other without any of their sides intersect nothing happen. After all looks good.

It's an old library now and does not do point inside poly checks, the new version does but that's not for public consumption - sorry.

doesnt work for me, i get the same error as the first post

The source is in the .exe just use it as an include.