Editer camera rotation

I'm currently working on a small editer for tokamak rigid bodies, and have run into the problem of camera rotation. I want the camera to rotate around the object, based on user mouse input in a similar way to editers like max(I only have gmax :P) or truespace. I've tried creating a pivot on the object, and then turning this based on mouse speeds but this messes up after multiple turns. Taking this, I tried maintaining the camera's pitch and yaw, and setting roll to 0. this was better, however pretty wierd. Anyone have some helpful code snipbits or methods?

Try this one ...

Global ML_cam_pivot = CreatePivot()
Global ML_cam_pivot2 = CreatePivot(ML_cam_pivot)
Global ML_camera = CreateCamera(ML_cam_pivot2)

Global x_speed#,y_speed#,z_speed#

Function mouselook()
	x_speed# = x_speed * 0.3 + MouseXSpeed() * 0.3 
	y_speed# = y_speed * 0.3 + MouseYSpeed() * 0.3 
	z_speed# = z_speed * 0.3 + MouseZSpeed() * 0.3

	MoveMouse GraphicsWidth()/2,GraphicsHeight()/2
		
	TurnEntity ML_cam_pivot,0,-x_speed,0	;turn player left/right
	TurnEntity ML_cam_pivot2,y_speed,0,0	;tilt camera
	MoveEntity ML_camera,0,0,z_speed	;zoom
End Function

Rough and ready, but works pretty nice.

Edit: Updated with Pan

LMB click an entity to focus on it
Left ALT + LMB to Rotate
Left ALT + RMB to Zoom
Left CTRL + LMB to Pan

Graphics3D 800,600,32,2

Global MOVECAMTARGET=0

Global camzoom#= -10.0
Global cam=CreateCamera()
Global campiv=CreatePivot()
EntityParent cam,campiv
PositionEntity cam,0,0,camzoom
CameraRange cam,.1,500

light=CreateLight()


Dim ent(10)
For i=1 To 10
	t=Rand(1,4)
	
	Select t
	Case 1
		ent(i)=CreateCube()
		ScaleEntity ent(i),.5,.5,.5
	Case 2
		ent(i)=CreateSphere()
		ScaleEntity ent(i),.5,.5,.5
	Case 3
		ent(i)=CreateCylinder()
		ScaleEntity ent(i),.5,.5,.5
	Case 4
		ent(i)=CreateCone()
		ScaleEntity ent(i),.5,.5,.5
	Default
	End Select
	
	EntityPickMode ent(i),2	; polygon pickable
	EntityColor ent(i),Rand(100,255),Rand(100,255),Rand(100,255)
	PositionEntity ent(i),Rnd(-10,10),Rnd(1.5,8),Rnd(-10,10)
Next

While Not KeyHit(1)

	If MouseHit(1)
		p=CameraPick(cam,MouseX(),MouseY())
		If p
			MOVECAMTARGET=PickedEntity()
		End If
	End If
	
	If KeyDown(56) And MouseDown(1) mouse_rotation()
	
	If KeyDown(56) And MouseDown(2) mouse_zoom()
	
	If KeyDown(29) And MouseDown(1) mouse_pan()

	If MOVECAMTARGET Then MoveCamTo()	
	
	UpdateWorld
	RenderWorld
	Flip
Wend
End


Function MoveCamTo()
	x#=EntityX#(MOVECAMTARGET,1) - EntityX#(campiv,1)
	y#=EntityY#(MOVECAMTARGET,1) - EntityY#(campiv,1)
	z#=EntityZ#(MOVECAMTARGET,1) - EntityZ#(campiv,1)

	If Abs(x) > .01 Or Abs(y) > .01 Or Abs(z) > .01
		PositionEntity campiv,EntityX#(campiv,1) + (x * .1),EntityY#(campiv,1) + (y * .1),EntityZ#(campiv,1) + (z * .1),1
	Else
		MOVECAMTARGET=0
	End If
End Function

Function mouse_rotation()
	oldx#=MouseX()
	oldy#=MouseY()
	currentyaw#=EntityYaw#(campiv,1)
	currentpitch#=EntityPitch#(campiv,1)
	While MouseDown(1)

		newx#= - (MouseX() - oldx) * .5 + currentyaw
		newy#= (MouseY() - oldy) * .5 + currentpitch
		
		If newy > 80 Then newy=80
		If newy < -80 Then newy = -80
		RotateEntity campiv,newy,newx,0,1
		
		If MOVECAMTARGET Then MoveCamTo()
		
		UpdateWorld
		RenderWorld
		Flip
	Wend
End Function

Function mouse_zoom()
	oldy#=MouseY()
	oldcamzoom#=camzoom
	While MouseDown(2)
		camzoom=  -(MouseY() - oldy) * .05 + oldcamzoom
		
		If camzoom < -30 Then camzoom = -30
		If camzoom > .5 Then camzoom = .5
				
		PositionEntity cam,0,0,camzoom
		
		If MOVECAMTARGET Then MoveCamTo()
		
		UpdateWorld
		RenderWorld
		Flip
	Wend
End Function

Function mouse_pan()
	oldx#=MouseX()
	oldy#=MouseY()
	temppiv=CreatePivot(campiv)
	EntityParent temppiv,0,1
	
	While MouseDown(1)

		newx#= - (MouseX() - oldx) * .02
		newy#= (MouseY() - oldy) * .02

		TFormPoint newx,newy,0,temppiv,0
		PositionEntity campiv,TFormedX(),TFormedY(),TFormedZ(),1
		
		If MOVECAMTARGET Then MoveCamTo()
		
		UpdateWorld
		RenderWorld
		Flip
	Wend
	FreeEntity temppiv
End Function

Cya!
Tom

cool. thanx :) nice demo btw, tom, some nice camera stuff in there.