forked from bartvdbraak/blender
Use the S matrix of the modifier CG algorithm for implementing collision
responses. The S matrix together with the z Vector encodes the degrees of freedom of a colliding hair point and the target velocity change. In a collision the hair vertex is restricted in the normal direction (when moving toward the collider) and the collision dynamics define target velocity.
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@ -44,6 +44,7 @@ struct ClothModifierData;
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struct CollisionModifierData;
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struct CollisionTree;
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struct VoxelData;
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struct PartDeflect;
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#define DO_INLINE MALWAYS_INLINE
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@ -201,6 +202,9 @@ void cloth_find_point_contacts(struct Object *ob, struct ClothModifierData *clmd
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ColliderContacts **r_collider_contacts, int *r_totcolliders);
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void cloth_free_contacts(ColliderContacts *collider_contacts, int totcolliders);
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bool cloth_points_collpair_response(struct ClothModifierData *clmd, struct CollisionModifierData *collmd, struct PartDeflect *pd,
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struct CollPair *collpair, float dt, float r_impulse[3]);
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////////////////////////////////////////////////
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@ -958,6 +958,82 @@ BLI_INLINE void max_v3_v3v3(float r[3], const float a[3], const float b[3])
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r[2] = max_ff(a[2], b[2]);
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}
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bool cloth_points_collpair_response(ClothModifierData *clmd, CollisionModifierData *collmd, PartDeflect *pd, CollPair *collpair, float dt, float r_impulse[3])
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{
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bool result = false;
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float restitution = (1.0f - clmd->coll_parms->damping) * (1.0f - pd->pdef_sbdamp);
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Cloth *cloth1 = clmd->clothObject;
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float u1, u2, u3;
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float v1[3], v2_old[3], v2_new[3], v_rel_old[3], v_rel_new[3];
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float epsilon2 = BLI_bvhtree_getepsilon ( collmd->bvhtree );
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float margin_distance = collpair->distance - epsilon2;
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float mag_v_rel;
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zero_v3(r_impulse);
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if (margin_distance > 0.0f)
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return false; /* XXX tested before already? */
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/* only handle static collisions here */
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if ( collpair->flag & COLLISION_IN_FUTURE )
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return false;
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/* compute barycentric coordinates */
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collision_compute_barycentric(collpair->pb,
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collmd->current_x[collpair->bp1].co,
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collmd->current_x[collpair->bp2].co,
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collmd->current_x[collpair->bp3].co,
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&u1, &u2, &u3 );
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/* Calculate relative velocity */
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copy_v3_v3(v1, cloth1->verts[collpair->ap1].tv);
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collision_interpolateOnTriangle(v2_new, collmd->current_v[collpair->bp1].co, collmd->current_v[collpair->bp2].co, collmd->current_v[collpair->bp3].co, u1, u2, u3);
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/* XXX assume constant velocity of the collider for now */
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copy_v3_v3(v2_old, v2_new);
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/* relative velocity = velocity of the cloth point relative to the collider */
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sub_v3_v3v3(v_rel_old, v1, v2_old);
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sub_v3_v3v3(v_rel_new, v1, v2_new);
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/* normal component of the relative velocity */
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mag_v_rel = dot_v3v3(v_rel_old, collpair->normal);
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/* only valid when moving toward the collider */
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if (mag_v_rel < -ALMOST_ZERO) {
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float v_nor_old, v_nor_new;
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float v_tan_old[3], v_tan_new[3];
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float bounce, repulse;
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/* Collision response based on
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* "Simulating Complex Hair with Robust Collision Handling" (Choe, Choi, Ko, ACM SIGGRAPH 2005)
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* http://graphics.snu.ac.kr/publications/2005-choe-HairSim/Choe_2005_SCA.pdf
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*/
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v_nor_old = mag_v_rel;
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v_nor_new = dot_v3v3(v_rel_new, collpair->normal);
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madd_v3_v3v3fl(v_tan_old, v_rel_old, collpair->normal, -v_nor_old);
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madd_v3_v3v3fl(v_tan_new, v_rel_new, collpair->normal, -v_nor_new);
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repulse = -margin_distance / dt + dot_v3v3(v1, collpair->normal);
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if (margin_distance < -epsilon2) {
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bounce = -v_nor_new + v_nor_old * restitution;
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mul_v3_v3fl(r_impulse, collpair->normal, max_ff(repulse, bounce));
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}
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else {
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bounce = 0.0f;
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mul_v3_v3fl(r_impulse, collpair->normal, repulse);
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}
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result = true;
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}
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return result;
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}
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static bool cloth_points_collision_response_static(ClothModifierData *clmd, CollisionModifierData *collmd, PartDeflect *pd,
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CollPair *collpair, CollPair *collision_end, float dt)
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{
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@ -349,8 +349,10 @@ static void print_sparse_matrix(fmatrix3x3 *m)
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{
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if (m) {
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unsigned int i;
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for (i = 0; i < m[0].vcount + m[0].scount; i++)
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for (i = 0; i < m[0].vcount + m[0].scount; i++) {
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printf("%d:\n", i);
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print_fmatrix(m[i].m);
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}
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}
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}
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#endif
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@ -1756,23 +1758,30 @@ bool implicit_hair_volume_get_texture_data(Object *UNUSED(ob), ClothModifierData
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/* ================================ */
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/* Init constraint matrix */
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static void setup_constraint_matrix(ClothVertex *verts, int numverts, ColliderContacts *contacts, int totcolliders, fmatrix3x3 *S, SimDebugData *debug_data)
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/* Init constraint matrix
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* This is part of the modified CG method suggested by Baraff/Witkin in
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* "Large Steps in Cloth Simulation" (Siggraph 1998)
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*/
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static void setup_constraint_matrix(ClothModifierData *clmd, ColliderContacts *contacts, int totcolliders, lfVector *V, fmatrix3x3 *S, lfVector *z, float dt)
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{
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int i, j;
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ClothVertex *verts = clmd->clothObject->verts;
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int numverts = clmd->clothObject->numverts;
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int i, j, v;
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/* Clear matrix from old vertex constraints */
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for (i = 0; i < S[0].vcount; i++)
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S[i].c = S[i].r = 0;
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for (v = 0; v < S[0].vcount; v++)
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S[v].c = S[v].r = 0;
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/* pinned vertex constraints */
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for (i = 0; i < numverts; i++) {
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S[i].c = S[i].r = i;
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if (verts[i].flags & CLOTH_VERT_FLAG_PINNED) {
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zero_m3(S[i].m);
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for (v = 0; v < numverts; v++) {
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S[v].c = S[v].r = v;
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if (verts[v].flags & CLOTH_VERT_FLAG_PINNED) {
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negate_v3_v3(z[v], verts[v].v);
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zero_m3(S[v].m);
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}
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else {
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unit_m3(S[i].m);
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zero_v3(z[v]);
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unit_m3(S[v].m);
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}
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}
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@ -1782,21 +1791,34 @@ static void setup_constraint_matrix(ClothVertex *verts, int numverts, ColliderCo
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CollPair *collpair = &ct->collisions[j];
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int v = collpair->face1;
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float cmat[3][3];
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float impulse[3];
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/* pinned verts handled separately */
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if (verts[v].flags & CLOTH_VERT_FLAG_PINNED)
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continue;
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/* calculate collision response */
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// if (!cloth_points_collpair_response(clmd, ct->collmd, ct->ob->pd, collpair, dt, impulse))
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// continue;
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cloth_points_collpair_response(clmd, ct->collmd, ct->ob->pd, collpair, dt, impulse);
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// add_v3_v3(z[v], impulse);
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negate_v3_v3(z[v], V[v]);
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// sub_v3_v3(z[v], verts[v].v);
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/* modify S to enforce velocity constraint in normal direction */
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mul_fvectorT_fvector(cmat, collpair->normal, collpair->normal);
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sub_m3_m3m3(S[v].m, I, cmat);
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BKE_sim_debug_data_add_dot(debug_data, collpair->pa, 0, 1, 0, "collision", hash_collpair(936, collpair));
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BKE_sim_debug_data_add_dot(debug_data, collpair->pb, 1, 0, 0, "collision", hash_collpair(937, collpair));
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BKE_sim_debug_data_add_line(debug_data, collpair->pa, collpair->pb, 0.7, 0.7, 0.7, "collision", hash_collpair(938, collpair));
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BKE_sim_debug_data_add_dot(clmd->debug_data, collpair->pa, 0, 1, 0, "collision", hash_collpair(936, collpair));
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BKE_sim_debug_data_add_dot(clmd->debug_data, collpair->pb, 1, 0, 0, "collision", hash_collpair(937, collpair));
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BKE_sim_debug_data_add_line(clmd->debug_data, collpair->pa, collpair->pb, 0.7, 0.7, 0.7, "collision", hash_collpair(938, collpair));
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{
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float nor[3];
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mul_v3_v3fl(nor, collpair->normal, collpair->distance);
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BKE_sim_debug_data_add_vector(debug_data, collpair->pb, nor, 1, 1, 0, "collision", hash_collpair(939, collpair));
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// float nor[3];
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// mul_v3_v3fl(nor, collpair->normal, collpair->distance);
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// BKE_sim_debug_data_add_vector(clmd->debug_data, collpair->pb, nor, 1, 1, 0, "collision", hash_collpair(939, collpair));
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BKE_sim_debug_data_add_vector(clmd->debug_data, collpair->pb, impulse, 1, 1, 0, "collision", hash_collpair(940, collpair));
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// BKE_sim_debug_data_add_vector(clmd->debug_data, collpair->pb, collpair->normal, 1, 1, 0, "collision", hash_collpair(941, collpair));
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}
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}
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}
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@ -2096,6 +2118,12 @@ int implicit_solver(Object *ob, float frame, ClothModifierData *clmd, ListBase *
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while (step < tf) {
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/* copy velocities for collision */
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for (i = 0; i < numverts; i++) {
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copy_v3_v3(verts[i].tv, id->V[i]);
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copy_v3_v3(verts[i].v, verts[i].tv);
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}
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/* determine contact points */
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if (clmd->coll_parms->flags & CLOTH_COLLSETTINGS_FLAG_ENABLED) {
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if (clmd->coll_parms->flags & CLOTH_COLLSETTINGS_FLAG_POINTS) {
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@ -2104,7 +2132,7 @@ int implicit_solver(Object *ob, float frame, ClothModifierData *clmd, ListBase *
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}
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/* setup vertex constraints for pinned vertices and contacts */
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setup_constraint_matrix(verts, cloth->numverts, contacts, totcolliders, id->S, clmd->debug_data);
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setup_constraint_matrix(clmd, contacts, totcolliders, id->V, id->S, id->z, dt);
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// damping velocity for artistic reasons
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mul_lfvectorS(id->V, id->V, clmd->sim_parms->vel_damping, numverts);
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