JV-ODE Physics Thread 5

Good Work Viper! Now that you can access fdir1 i have decided to release here the code to make proper wheels friction:

	Vector3 front;
	Vector3 up;
	dReal const * vel = dBodyGetLinearVel( wheel );

	int inv = 1;
	//  Compute fDir1 if a wheel
	dReal const * R = dBodyGetRotation( wheel );
	front = Vector3(R[2] * inv,R[6] * inv,R[10] * inv);
	up = Vector3(R[1] * inv,R[5] * inv,R[9] * inv);
		//  Set Slip2
	contact->surface.mode |= dContactFDir1;
	float v = sqrtf( vel[0]*vel[0] + vel[1]*vel[1] + vel[2]*vel[2] );
	//contact.surface.slip2 = TIRE_SLIP * v;				
	//  re-tweak mu and mu2
	//contact.surface.mu = contact.surface.mu2 = TIRE_MU;
	//  The theory is that it doesn't matter if "front" points "up" 
	//  because we want fdir2 to be orthogonal to "front" and contact 
	//  normal. Of course, if "front" points in the direction of the 
	//  contact, this can be a problem. In that case, choose "up".
	if( fabsf( dDot( contact->geom.normal, &front.x, 3 ) ) > 0.5f ) 
		{
		((Vector3 &)contact->fdir1) = up;
		}
	else
		{
		((Vector3 &)contact->fdir1) = front;
		}

Dvector3 is float[3] and dReal is float.

The code is based on the cardemo of official ode threads, and it is c++, but it should be easy to be included by Viper on the wrapper or by anyone in Blitz3D!

Happy Holidays Everyone!