[ODE] Question about collision detection

[ron taņeza]

Hi,

I'm modifying test_buggy.. I added a wall (actually a box), and when the buggy collides with it, it should move in the opposite direction. I did this (in SimLoop):
..
dSpaceCollide (space,0,&nearCallback);

	int j;
	dContact contactwall[10];
	j = dCollide (wall1,geom_group,10,&contactwall[0].geom,sizeof(dContact));
	//wall1 is of type static dGeomID
	if (j>0)
	{			
		speed = -speed;
		dsPrint("Collided with wall!\n");
	}

dWorldStep (world,0.05);
..

It doesn't work. I mean, the buggy still bumps the wall, but it doesn't change direction. I also tried adding the code above to the NearCallBack function, but without success. Is there a function that takes just two dGeomID arguments, and returns nonzero if those two collide? Maybe I placed my code in the wrong place? I don't fully understand collision detection in ODE, as I'm really new to physics/game programming. If anyone can show me how to do something like.. if (buggy bumps wall), then do (something).. I'd really appreciate it.

Help!


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