void EulerStep (ParticleSystem p, double delta_t)
{
int dim = ParticleStateDim (p);
int spacedim;
// double crossFraction;
spacedim = 3; // we handle 3D always
GetParticleState (p, p->state_old.Ref());
ParticleDerivative (p, p->state_dot.Ref());
p->state_new = p->state_old + delta_t * p->state_dot;
// CombinedVector (1.0, p->state_old, delta_t, p->state_dot, p->state_new, dim);
// anchor particles do not move
for (unsigned int i = 0; i < p->particles.size(); i++) {
if (p->particles[i]->anchor) {
for (int ii = 0; ii < spacedim; ii++) {
p->state_new[2*spacedim*i+ii] = p->state_old[2*spacedim*i+ii];
p->state_new[2*spacedim*i+ii+spacedim] = 0.0;
}
}
}
}
void SpringSys::UpdateParticleState(TimeValue t, Tab<Matrix3> tmArray, int index, TimeValue Delta)
{
Point3 t_pos, t_vel, orig_pos, orig_vel;
Matrix3 tm;
for (int b=0;b<parts[index].GetSprings()->length();b++)
{
if (parts[index].GetSpring(b)->GetPointConstraint()->GetIndex() < tmArray.Count())
{
tm = tmArray[parts[index].GetSpring(b)->GetPointConstraint()->index];
ComputeControlledParticleForce(tm, index, b); /* compute bone deriv used by ApplySpring */
}
}
Clear_Forces(index); /* zero the force accumulators */
Compute_Forces(t, index); /* magic force function */
ComputeDerivative(index, t_pos, t_vel); /* get deriv */
//ComputeDerivative(pIndex, t_pos, t_vel, Delta); /* get deriv */
ScaleVectors(t_pos, t_vel, Delta); /* scale it */
GetParticleState(index, orig_pos, orig_vel); /* get state */
AddVectors(orig_pos, orig_vel, t_pos, t_vel); /* add -> temp2 */
SetParticleState(index, t_pos, t_vel); /* update state */
}
