/* Init constraint matrix
* This is part of the modified CG method suggested by Baraff/Witkin in
* "Large Steps in Cloth Simulation" (Siggraph 1998)
*/
static void cloth_setup_constraints(ClothModifierData *clmd, ColliderContacts *contacts, int totcolliders, float dt)
{
Cloth *cloth = clmd->clothObject;
Implicit_Data *data = cloth->implicit;
ClothVertex *verts = cloth->verts;
int mvert_num = cloth->mvert_num;
int i, j, v;
const float ZERO[3] = {0.0f, 0.0f, 0.0f};
BPH_mass_spring_clear_constraints(data);
for (v = 0; v < mvert_num; v++) {
if (verts[v].flags & CLOTH_VERT_FLAG_PINNED) {
/* pinned vertex constraints */
BPH_mass_spring_add_constraint_ndof0(data, v, ZERO); /* velocity is defined externally */
}
verts[v].impulse_count = 0;
}
for (i = 0; i < totcolliders; ++i) {
ColliderContacts *ct = &contacts[i];
for (j = 0; j < ct->totcollisions; ++j) {
CollPair *collpair = &ct->collisions[j];
// float restitution = (1.0f - clmd->coll_parms->damping) * (1.0f - ct->ob->pd->pdef_sbdamp);
float restitution = 0.0f;
int v = collpair->face1;
float impulse[3];
/* pinned verts handled separately */
if (verts[v].flags & CLOTH_VERT_FLAG_PINNED)
continue;
/* XXX cheap way of avoiding instability from multiple collisions in the same step
* this should eventually be supported ...
*/
if (verts[v].impulse_count > 0)
continue;
/* calculate collision response */
if (!collision_response(clmd, ct->collmd, collpair, dt, restitution, impulse))
continue;
BPH_mass_spring_add_constraint_ndof2(data, v, collpair->normal, impulse);
++verts[v].impulse_count;
}
}
}
/*
* void collision_check();
*
* determines if any ball-wall or ball-ball collisions occur
*/
void collision_check() {
int i, j;
double d;
for(i = 0; i < all_spheres.size(); i++) {
wall_check(&all_spheres[i]);
// ball-ball collisions
if( i < all_spheres.size()-1 ){
for( j = i+1; j < all_spheres.size(); j++) {
if(all_spheres[i].ghost + all_spheres[j].ghost >= 1) {
continue;
}
d = distance(all_spheres[i], all_spheres[j]);
// if a collision
if( d <= all_spheres[i].radius + all_spheres[j].radius) {
// COLLISION RESPONSE STARTS
// two curves colliding, need to generate direction vectors
if(all_spheres[i].path + all_spheres[j].path == 2){
{
update_direction(&all_spheres[i]);
update_direction(&all_spheres[j]);
}
// one curve and 1 ball collide, need to generate vector
}else if(all_spheres[i].path + all_spheres[j].path == 1){
if(all_spheres[i].path == 1) { //[i] is the curved ball
update_direction(&all_spheres[i]);
}else{ //[j] is the curved ball
update_direction(&all_spheres[j]);
}
// END BALL-CURVE
}
nudge_spheres(&all_spheres[i], &all_spheres[j], d);
collision_response(&all_spheres[i], &all_spheres[j]);
}
}
}
// end ball-ball
}
}