[ODE] Contacts not constraining user forces ?

[Marco Grubert]

Hello,

I ran into a strange problem in a simple test case: a sphere dropped onto a 
static Trimesh with any world gravity enabled comes to a rest on top of the 
trimesh. If however I adda tiny amount of force using dBodyAddForce before 
stepping then the sphere sinks into that mesh.
Any suggestions on what might be going wrong ?

// this works fine:
dWorldSetGravity(0,0,-380);
while (1) {
  // add contacts here
  dWorldStep( pWorld, 0.05f );
};
///////////////////////////////////////////
// this makes the sphere sink
dWorldSetGravity(0,0,-380);
while (1) {
  dBodyAddForce( pSphereBody, 0,0,-1);
  // add contacts here
  dWorldStep( pWorld, 0.05f );
};

- Marco