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Diffstat (limited to 'source/blender/physics/intern/BPH_mass_spring.cpp')
| -rw-r--r-- | source/blender/physics/intern/BPH_mass_spring.cpp | 1117 |
1 files changed, 1117 insertions, 0 deletions
diff --git a/source/blender/physics/intern/BPH_mass_spring.cpp b/source/blender/physics/intern/BPH_mass_spring.cpp new file mode 100644 index 00000000000..30a8478e0e4 --- /dev/null +++ b/source/blender/physics/intern/BPH_mass_spring.cpp @@ -0,0 +1,1117 @@ +/*
+ * ***** BEGIN GPL LICENSE BLOCK *****
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ *
+ * The Original Code is Copyright (C) Blender Foundation
+ * All rights reserved.
+ *
+ * The Original Code is: all of this file.
+ *
+ * Contributor(s): Lukas Toenne
+ *
+ * ***** END GPL LICENSE BLOCK *****
+ */
+
+/** \file blender/physics/intern/BPH_mass_spring.cpp
+ * \ingroup bph
+ */
+
+extern "C" {
+#include "MEM_guardedalloc.h"
+
+#include "DNA_cloth_types.h"
+#include "DNA_scene_types.h"
+#include "DNA_object_force.h"
+#include "DNA_object_types.h"
+#include "DNA_meshdata_types.h"
+#include "DNA_modifier_types.h"
+
+#include "BLI_math.h"
+#include "BLI_linklist.h"
+#include "BLI_utildefines.h"
+
+#include "BKE_cloth.h"
+#include "BKE_collision.h"
+#include "BKE_effect.h"
+}
+
+#include "BPH_mass_spring.h"
+#include "implicit.h"
+
+static float I3[3][3] = {{1.0, 0.0, 0.0}, {0.0, 1.0, 0.0}, {0.0, 0.0, 1.0}};
+
+/* Number of off-diagonal non-zero matrix blocks.
+ * Basically there is one of these for each vertex-vertex interaction.
+ */
+static int cloth_count_nondiag_blocks(Cloth *cloth)
+{
+ LinkNode *link;
+ int nondiag = 0;
+
+ for (link = cloth->springs; link; link = link->next) {
+ ClothSpring *spring = (ClothSpring *)link->link;
+ switch (spring->type) {
+ case CLOTH_SPRING_TYPE_BENDING_ANG:
+ /* angular bending combines 3 vertices */
+ nondiag += 3;
+ break;
+
+ default:
+ /* all other springs depend on 2 vertices only */
+ nondiag += 1;
+ break;
+ }
+ }
+
+ return nondiag;
+}
+
+int BPH_cloth_solver_init(Object *UNUSED(ob), ClothModifierData *clmd)
+{
+ Cloth *cloth = clmd->clothObject;
+ ClothVertex *verts = cloth->verts;
+ const float ZERO[3] = {0.0f, 0.0f, 0.0f};
+ Implicit_Data *id;
+ unsigned int i, nondiag;
+
+ nondiag = cloth_count_nondiag_blocks(cloth);
+ cloth->implicit = id = BPH_mass_spring_solver_create(cloth->mvert_num, nondiag);
+
+ for (i = 0; i < cloth->mvert_num; i++) {
+ BPH_mass_spring_set_vertex_mass(id, i, verts[i].mass);
+ }
+
+ for (i = 0; i < cloth->mvert_num; i++) {
+ BPH_mass_spring_set_motion_state(id, i, verts[i].x, ZERO);
+ }
+
+ return 1;
+}
+
+void BPH_cloth_solver_free(ClothModifierData *clmd)
+{
+ Cloth *cloth = clmd->clothObject;
+
+ if (cloth->implicit) {
+ BPH_mass_spring_solver_free(cloth->implicit);
+ cloth->implicit = NULL;
+ }
+}
+
+void BKE_cloth_solver_set_positions(ClothModifierData *clmd)
+{
+ Cloth *cloth = clmd->clothObject;
+ ClothVertex *verts = cloth->verts;
+ unsigned int mvert_num = cloth->mvert_num, i;
+ ClothHairData *cloth_hairdata = clmd->hairdata;
+ Implicit_Data *id = cloth->implicit;
+
+ for (i = 0; i < mvert_num; i++) {
+ if (cloth_hairdata) {
+ ClothHairData *root = &cloth_hairdata[i];
+ BPH_mass_spring_set_rest_transform(id, i, root->rot);
+ }
+ else
+ BPH_mass_spring_set_rest_transform(id, i, I3);
+
+ BPH_mass_spring_set_motion_state(id, i, verts[i].x, verts[i].v);
+ }
+}
+
+static bool collision_response(ClothModifierData *clmd, CollisionModifierData *collmd, CollPair *collpair, float dt, float restitution, float r_impulse[3])
+{
+ Cloth *cloth = clmd->clothObject;
+ int index = collpair->ap1;
+ bool result = false;
+
+ float v1[3], v2_old[3], v2_new[3], v_rel_old[3], v_rel_new[3];
+ float epsilon2 = BLI_bvhtree_getepsilon(collmd->bvhtree);
+
+ float margin_distance = (float)collpair->distance - epsilon2;
+ float mag_v_rel;
+
+ zero_v3(r_impulse);
+
+ if (margin_distance > 0.0f)
+ return false; /* XXX tested before already? */
+
+ /* only handle static collisions here */
+ if ( collpair->flag & COLLISION_IN_FUTURE )
+ return false;
+
+ /* velocity */
+ copy_v3_v3(v1, cloth->verts[index].v);
+ collision_get_collider_velocity(v2_old, v2_new, collmd, collpair);
+ /* relative velocity = velocity of the cloth point relative to the collider */
+ sub_v3_v3v3(v_rel_old, v1, v2_old);
+ sub_v3_v3v3(v_rel_new, v1, v2_new);
+ /* normal component of the relative velocity */
+ mag_v_rel = dot_v3v3(v_rel_old, collpair->normal);
+
+ /* only valid when moving toward the collider */
+ if (mag_v_rel < -ALMOST_ZERO) {
+ float v_nor_old, v_nor_new;
+ float v_tan_old[3], v_tan_new[3];
+ float bounce, repulse;
+
+ /* Collision response based on
+ * "Simulating Complex Hair with Robust Collision Handling" (Choe, Choi, Ko, ACM SIGGRAPH 2005)
+ * http://graphics.snu.ac.kr/publications/2005-choe-HairSim/Choe_2005_SCA.pdf
+ */
+
+ v_nor_old = mag_v_rel;
+ v_nor_new = dot_v3v3(v_rel_new, collpair->normal);
+
+ madd_v3_v3v3fl(v_tan_old, v_rel_old, collpair->normal, -v_nor_old);
+ madd_v3_v3v3fl(v_tan_new, v_rel_new, collpair->normal, -v_nor_new);
+
+ bounce = -v_nor_old * restitution;
+
+ repulse = -margin_distance / dt; /* base repulsion velocity in normal direction */
+ /* XXX this clamping factor is quite arbitrary ...
+ * not sure if there is a more scientific approach, but seems to give good results
+ */
+ CLAMP(repulse, 0.0f, 4.0f * bounce);
+
+ if (margin_distance < -epsilon2) {
+ mul_v3_v3fl(r_impulse, collpair->normal, max_ff(repulse, bounce) - v_nor_new);
+ }
+ else {
+ bounce = 0.0f;
+ mul_v3_v3fl(r_impulse, collpair->normal, repulse - v_nor_new);
+ }
+
+ result = true;
+ }
+
+ return result;
+}
+
+/* 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;
+ }
+ }
+}
+
+/* computes where the cloth would be if it were subject to perfectly stiff edges
+ * (edge distance constraints) in a lagrangian solver. then add forces to help
+ * guide the implicit solver to that state. this function is called after
+ * collisions*/
+static int UNUSED_FUNCTION(cloth_calc_helper_forces)(Object *UNUSED(ob), ClothModifierData *clmd, float (*initial_cos)[3], float UNUSED(step), float dt)
+{
+ Cloth *cloth= clmd->clothObject;
+ float (*cos)[3] = (float (*)[3])MEM_callocN(sizeof(float[3]) * cloth->mvert_num, "cos cloth_calc_helper_forces");
+ float *masses = (float *)MEM_callocN(sizeof(float) * cloth->mvert_num, "cos cloth_calc_helper_forces");
+ LinkNode *node;
+ ClothSpring *spring;
+ ClothVertex *cv;
+ int i, steps;
+
+ cv = cloth->verts;
+ for (i = 0; i < cloth->mvert_num; i++, cv++) {
+ copy_v3_v3(cos[i], cv->tx);
+
+ if (cv->goal == 1.0f || len_squared_v3v3(initial_cos[i], cv->tx) != 0.0f) {
+ masses[i] = 1e+10;
+ }
+ else {
+ masses[i] = cv->mass;
+ }
+ }
+
+ steps = 55;
+ for (i=0; i<steps; i++) {
+ for (node=cloth->springs; node; node=node->next) {
+ /* ClothVertex *cv1, *cv2; */ /* UNUSED */
+ int v1, v2;
+ float len, c, l, vec[3];
+
+ spring = (ClothSpring *)node->link;
+ if (spring->type != CLOTH_SPRING_TYPE_STRUCTURAL && spring->type != CLOTH_SPRING_TYPE_SHEAR)
+ continue;
+
+ v1 = spring->ij; v2 = spring->kl;
+ /* cv1 = cloth->verts + v1; */ /* UNUSED */
+ /* cv2 = cloth->verts + v2; */ /* UNUSED */
+ len = len_v3v3(cos[v1], cos[v2]);
+
+ sub_v3_v3v3(vec, cos[v1], cos[v2]);
+ normalize_v3(vec);
+
+ c = (len - spring->restlen);
+ if (c == 0.0f)
+ continue;
+
+ l = c / ((1.0f / masses[v1]) + (1.0f / masses[v2]));
+
+ mul_v3_fl(vec, -(1.0f / masses[v1]) * l);
+ add_v3_v3(cos[v1], vec);
+
+ sub_v3_v3v3(vec, cos[v2], cos[v1]);
+ normalize_v3(vec);
+
+ mul_v3_fl(vec, -(1.0f / masses[v2]) * l);
+ add_v3_v3(cos[v2], vec);
+ }
+ }
+
+ cv = cloth->verts;
+ for (i = 0; i < cloth->mvert_num; i++, cv++) {
+ float vec[3];
+
+ /*compute forces*/
+ sub_v3_v3v3(vec, cos[i], cv->tx);
+ mul_v3_fl(vec, cv->mass*dt*20.0f);
+ add_v3_v3(cv->tv, vec);
+ //copy_v3_v3(cv->tx, cos[i]);
+ }
+
+ MEM_freeN(cos);
+ MEM_freeN(masses);
+
+ return 1;
+}
+
+BLI_INLINE void cloth_calc_spring_force(ClothModifierData *clmd, ClothSpring *s, float time)
+{
+ Cloth *cloth = clmd->clothObject;
+ ClothSimSettings *parms = clmd->sim_parms;
+ Implicit_Data *data = cloth->implicit;
+ ClothVertex *verts = cloth->verts;
+
+ bool no_compress = parms->flags & CLOTH_SIMSETTINGS_FLAG_NO_SPRING_COMPRESS;
+
+ zero_v3(s->f);
+ zero_m3(s->dfdx);
+ zero_m3(s->dfdv);
+
+ s->flags &= ~CLOTH_SPRING_FLAG_NEEDED;
+
+ // calculate force of structural + shear springs
+ if ((s->type & CLOTH_SPRING_TYPE_STRUCTURAL) || (s->type & CLOTH_SPRING_TYPE_SHEAR) || (s->type & CLOTH_SPRING_TYPE_SEWING) ) {
+#ifdef CLOTH_FORCE_SPRING_STRUCTURAL
+ float k, scaling;
+
+ s->flags |= CLOTH_SPRING_FLAG_NEEDED;
+
+ scaling = parms->structural + s->stiffness * fabsf(parms->max_struct - parms->structural);
+ k = scaling / (parms->avg_spring_len + FLT_EPSILON);
+
+ if (s->type & CLOTH_SPRING_TYPE_SEWING) {
+ // TODO: verify, half verified (couldn't see error)
+ // sewing springs usually have a large distance at first so clamp the force so we don't get tunnelling through colission objects
+ BPH_mass_spring_force_spring_linear(data, s->ij, s->kl, s->restlen, k, parms->Cdis, no_compress, parms->max_sewing, s->f, s->dfdx, s->dfdv);
+ }
+ else {
+ BPH_mass_spring_force_spring_linear(data, s->ij, s->kl, s->restlen, k, parms->Cdis, no_compress, 0.0f, s->f, s->dfdx, s->dfdv);
+ }
+#endif
+ }
+ else if (s->type & CLOTH_SPRING_TYPE_GOAL) {
+#ifdef CLOTH_FORCE_SPRING_GOAL
+ float goal_x[3], goal_v[3];
+ float k, scaling;
+
+ s->flags |= CLOTH_SPRING_FLAG_NEEDED;
+
+ // current_position = xold + t * (newposition - xold)
+ interp_v3_v3v3(goal_x, verts[s->ij].xold, verts[s->ij].xconst, time);
+ sub_v3_v3v3(goal_v, verts[s->ij].xconst, verts[s->ij].xold); // distance covered over dt==1
+
+ scaling = parms->goalspring + s->stiffness * fabsf(parms->max_struct - parms->goalspring);
+ k = verts[s->ij].goal * scaling / (parms->avg_spring_len + FLT_EPSILON);
+
+ BPH_mass_spring_force_spring_goal(data, s->ij, goal_x, goal_v, k, parms->goalfrict * 0.01f, s->f, s->dfdx, s->dfdv);
+#endif
+ }
+ else if (s->type & CLOTH_SPRING_TYPE_BENDING) { /* calculate force of bending springs */
+#ifdef CLOTH_FORCE_SPRING_BEND
+ float kb, cb, scaling;
+
+ s->flags |= CLOTH_SPRING_FLAG_NEEDED;
+
+ scaling = parms->bending + s->stiffness * fabsf(parms->max_bend - parms->bending);
+ kb = scaling / (20.0f * (parms->avg_spring_len + FLT_EPSILON));
+
+ // Fix for [#45084] for cloth stiffness must have cb proportional to kb
+ cb = kb * parms->bending_damping;
+
+ BPH_mass_spring_force_spring_bending(data, s->ij, s->kl, s->restlen, kb, cb, s->f, s->dfdx, s->dfdv);
+#endif
+ }
+ else if (s->type & CLOTH_SPRING_TYPE_BENDING_ANG) {
+#ifdef CLOTH_FORCE_SPRING_BEND
+ float kb, cb, scaling;
+
+ s->flags |= CLOTH_SPRING_FLAG_NEEDED;
+
+ /* XXX WARNING: angular bending springs for hair apply stiffness factor as an overall factor, unlike cloth springs!
+ * this is crap, but needed due to cloth/hair mixing ...
+ * max_bend factor is not even used for hair, so ...
+ */
+ scaling = s->stiffness * parms->bending;
+ kb = scaling / (20.0f * (parms->avg_spring_len + FLT_EPSILON));
+
+ // Fix for [#45084] for cloth stiffness must have cb proportional to kb
+ cb = kb * parms->bending_damping;
+
+ /* XXX assuming same restlen for ij and jk segments here, this can be done correctly for hair later */
+ BPH_mass_spring_force_spring_bending_angular(data, s->ij, s->kl, s->mn, s->target, kb, cb);
+
+#if 0
+ {
+ float x_kl[3], x_mn[3], v[3], d[3];
+
+ BPH_mass_spring_get_motion_state(data, s->kl, x_kl, v);
+ BPH_mass_spring_get_motion_state(data, s->mn, x_mn, v);
+
+ BKE_sim_debug_data_add_dot(clmd->debug_data, x_kl, 0.9, 0.9, 0.9, "target", 7980, s->kl);
+ BKE_sim_debug_data_add_line(clmd->debug_data, x_kl, x_mn, 0.8, 0.8, 0.8, "target", 7981, s->kl);
+
+ copy_v3_v3(d, s->target);
+ BKE_sim_debug_data_add_vector(clmd->debug_data, x_kl, d, 0.8, 0.8, 0.2, "target", 7982, s->kl);
+
+// copy_v3_v3(d, s->target_ij);
+// BKE_sim_debug_data_add_vector(clmd->debug_data, x, d, 1, 0.4, 0.4, "target", 7983, s->kl);
+ }
+#endif
+#endif
+ }
+}
+
+static void hair_get_boundbox(ClothModifierData *clmd, float gmin[3], float gmax[3])
+{
+ Cloth *cloth = clmd->clothObject;
+ Implicit_Data *data = cloth->implicit;
+ unsigned int looptri_num = cloth->tri_num;
+ int i;
+
+ INIT_MINMAX(gmin, gmax);
+ for (i = 0; i < looptri_num; i++) {
+ float x[3];
+ BPH_mass_spring_get_motion_state(data, i, x, NULL);
+ DO_MINMAX(x, gmin, gmax);
+ }
+}
+
+static void cloth_calc_force(ClothModifierData *clmd, float UNUSED(frame), ListBase *effectors, float time)
+{
+ /* Collect forces and derivatives: F, dFdX, dFdV */
+ Cloth *cloth = clmd->clothObject;
+ Implicit_Data *data = cloth->implicit;
+ unsigned int i = 0;
+ float drag = clmd->sim_parms->Cvi * 0.01f; /* viscosity of air scaled in percent */
+ float gravity[3] = {0.0f, 0.0f, 0.0f};
+ const MVertTri *tri = cloth->tri;
+ unsigned int mvert_num = cloth->mvert_num;
+ ClothVertex *vert;
+
+#ifdef CLOTH_FORCE_GRAVITY
+ /* global acceleration (gravitation) */
+ if (clmd->scene->physics_settings.flag & PHYS_GLOBAL_GRAVITY) {
+ /* scale gravity force */
+ mul_v3_v3fl(gravity, clmd->scene->physics_settings.gravity, 0.001f * clmd->sim_parms->effector_weights->global_gravity);
+ }
+ vert = cloth->verts;
+ for (i = 0; i < cloth->mvert_num; i++, vert++) {
+ BPH_mass_spring_force_gravity(data, i, vert->mass, gravity);
+ }
+#endif
+
+ /* cloth_calc_volume_force(clmd); */
+
+#ifdef CLOTH_FORCE_DRAG
+ BPH_mass_spring_force_drag(data, drag);
+#endif
+
+ /* handle external forces like wind */
+ if (effectors) {
+ /* cache per-vertex forces to avoid redundant calculation */
+ float (*winvec)[3] = (float (*)[3])MEM_callocN(sizeof(float[3]) * mvert_num, "effector forces");
+ for (i = 0; i < cloth->mvert_num; i++) {
+ float x[3], v[3];
+ EffectedPoint epoint;
+
+ BPH_mass_spring_get_motion_state(data, i, x, v);
+ pd_point_from_loc(clmd->scene, x, v, i, &epoint);
+ pdDoEffectors(effectors, NULL, clmd->sim_parms->effector_weights, &epoint, winvec[i], NULL);
+ }
+
+ for (i = 0; i < cloth->tri_num; i++) {
+ const MVertTri *vt = &tri[i];
+ BPH_mass_spring_force_face_wind(data, vt->tri[0], vt->tri[1], vt->tri[2], winvec);
+ }
+
+ /* Hair has only edges */
+ if (cloth->tri_num == 0) {
+#if 0
+ ClothHairData *hairdata = clmd->hairdata;
+ ClothHairData *hair_ij, *hair_kl;
+
+ for (LinkNode *link = cloth->springs; link; link = link->next) {
+ ClothSpring *spring = (ClothSpring *)link->link;
+ if (spring->type == CLOTH_SPRING_TYPE_STRUCTURAL) {
+ if (hairdata) {
+ hair_ij = &hairdata[spring->ij];
+ hair_kl = &hairdata[spring->kl];
+ BPH_mass_spring_force_edge_wind(data, spring->ij, spring->kl, hair_ij->radius, hair_kl->radius, winvec);
+ }
+ else
+ BPH_mass_spring_force_edge_wind(data, spring->ij, spring->kl, 1.0f, 1.0f, winvec);
+ }
+ }
+#else
+ ClothHairData *hairdata = clmd->hairdata;
+
+ vert = cloth->verts;
+ for (i = 0; i < cloth->mvert_num; i++, vert++) {
+ if (hairdata) {
+ ClothHairData *hair = &hairdata[i];
+ BPH_mass_spring_force_vertex_wind(data, i, hair->radius, winvec);
+ }
+ else
+ BPH_mass_spring_force_vertex_wind(data, i, 1.0f, winvec);
+ }
+ }
+#endif
+
+ MEM_freeN(winvec);
+ }
+
+ // calculate spring forces
+ for (LinkNode *link = cloth->springs; link; link = link->next) {
+ ClothSpring *spring = (ClothSpring *)link->link;
+ // only handle active springs
+ if (!(spring->flags & CLOTH_SPRING_FLAG_DEACTIVATE))
+ cloth_calc_spring_force(clmd, spring, time);
+ }
+}
+
+/* returns vertexes' motion state */
+BLI_INLINE void cloth_get_grid_location(Implicit_Data *data, float cell_scale, const float cell_offset[3],
+ int index, float x[3], float v[3])
+{
+ BPH_mass_spring_get_position(data, index, x);
+ BPH_mass_spring_get_new_velocity(data, index, v);
+
+ mul_v3_fl(x, cell_scale);
+ add_v3_v3(x, cell_offset);
+}
+
+/* returns next spring forming a continous hair sequence */
+BLI_INLINE LinkNode *hair_spring_next(LinkNode *spring_link)
+{
+ ClothSpring *spring = (ClothSpring *)spring_link->link;
+ LinkNode *next = spring_link->next;
+ if (next) {
+ ClothSpring *next_spring = (ClothSpring *)next->link;
+ if (next_spring->type == CLOTH_SPRING_TYPE_STRUCTURAL && next_spring->kl == spring->ij)
+ return next;
+ }
+ return NULL;
+}
+
+/* XXX this is nasty: cloth meshes do not explicitly store
+ * the order of hair segments!
+ * We have to rely on the spring build function for now,
+ * which adds structural springs in reverse order:
+ * (3,4), (2,3), (1,2)
+ * This is currently the only way to figure out hair geometry inside this code ...
+ */
+static LinkNode *cloth_continuum_add_hair_segments(HairGrid *grid, const float cell_scale, const float cell_offset[3], Cloth *cloth, LinkNode *spring_link)
+{
+ Implicit_Data *data = cloth->implicit;
+ LinkNode *next_spring_link = NULL; /* return value */
+ ClothSpring *spring1, *spring2, *spring3;
+ // ClothVertex *verts = cloth->verts;
+ // ClothVertex *vert3, *vert4;
+ float x1[3], v1[3], x2[3], v2[3], x3[3], v3[3], x4[3], v4[3];
+ float dir1[3], dir2[3], dir3[3];
+
+ spring1 = NULL;
+ spring2 = NULL;
+ spring3 = (ClothSpring *)spring_link->link;
+
+ zero_v3(x1); zero_v3(v1);
+ zero_v3(dir1);
+ zero_v3(x2); zero_v3(v2);
+ zero_v3(dir2);
+
+ // vert3 = &verts[spring3->kl];
+ cloth_get_grid_location(data, cell_scale, cell_offset, spring3->kl, x3, v3);
+ // vert4 = &verts[spring3->ij];
+ cloth_get_grid_location(data, cell_scale, cell_offset, spring3->ij, x4, v4);
+ sub_v3_v3v3(dir3, x4, x3);
+ normalize_v3(dir3);
+
+ while (spring_link) {
+ /* move on */
+ spring1 = spring2;
+ spring2 = spring3;
+
+ // vert3 = vert4;
+
+ copy_v3_v3(x1, x2); copy_v3_v3(v1, v2);
+ copy_v3_v3(x2, x3); copy_v3_v3(v2, v3);
+ copy_v3_v3(x3, x4); copy_v3_v3(v3, v4);
+
+ copy_v3_v3(dir1, dir2);
+ copy_v3_v3(dir2, dir3);
+
+ /* read next segment */
+ next_spring_link = spring_link->next;
+ spring_link = hair_spring_next(spring_link);
+
+ if (spring_link) {
+ spring3 = (ClothSpring *)spring_link->link;
+ // vert4 = &verts[spring3->ij];
+ cloth_get_grid_location(data, cell_scale, cell_offset, spring3->ij, x4, v4);
+ sub_v3_v3v3(dir3, x4, x3);
+ normalize_v3(dir3);
+ }
+ else {
+ spring3 = NULL;
+ // vert4 = NULL;
+ zero_v3(x4); zero_v3(v4);
+ zero_v3(dir3);
+ }
+
+ BPH_hair_volume_add_segment(grid, x1, v1, x2, v2, x3, v3, x4, v4,
+ spring1 ? dir1 : NULL,
+ dir2,
+ spring3 ? dir3 : NULL);
+ }
+
+ return next_spring_link;
+}
+
+static void cloth_continuum_fill_grid(HairGrid *grid, Cloth *cloth)
+{
+#if 0
+ Implicit_Data *data = cloth->implicit;
+ int mvert_num = cloth->mvert_num;
+ ClothVertex *vert;
+ int i;
+
+ for (i = 0, vert = cloth->verts; i < mvert_num; i++, vert++) {
+ float x[3], v[3];
+
+ cloth_get_vertex_motion_state(data, vert, x, v);
+ BPH_hair_volume_add_vertex(grid, x, v);
+ }
+#else
+ LinkNode *link;
+ float cellsize, gmin[3], cell_scale, cell_offset[3];
+
+ /* scale and offset for transforming vertex locations into grid space
+ * (cell size is 0..1, gmin becomes origin)
+ */
+ BPH_hair_volume_grid_geometry(grid, &cellsize, NULL, gmin, NULL);
+ cell_scale = cellsize > 0.0f ? 1.0f / cellsize : 0.0f;
+ mul_v3_v3fl(cell_offset, gmin, cell_scale);
+ negate_v3(cell_offset);
+
+ link = cloth->springs;
+ while (link) {
+ ClothSpring *spring = (ClothSpring *)link->link;
+ if (spring->type == CLOTH_SPRING_TYPE_STRUCTURAL)
+ link = cloth_continuum_add_hair_segments(grid, cell_scale, cell_offset, cloth, link);
+ else
+ link = link->next;
+ }
+#endif
+ BPH_hair_volume_normalize_vertex_grid(grid);
+}
+
+static void cloth_continuum_step(ClothModifierData *clmd, float dt)
+{
+ ClothSimSettings *parms = clmd->sim_parms;
+ Cloth *cloth = clmd->clothObject;
+ Implicit_Data *data = cloth->implicit;
+ int mvert_num = cloth->mvert_num;
+ ClothVertex *vert;
+
+ const float fluid_factor = 0.95f; /* blend between PIC and FLIP methods */
+ float smoothfac = parms->velocity_smooth;
+ /* XXX FIXME arbitrary factor!!! this should be based on some intuitive value instead,
+ * like number of hairs per cell and time decay instead of "strength"
+ */
+ float density_target = parms->density_target;
+ float density_strength = parms->density_strength;
+ float gmin[3], gmax[3];
+ int i;
+
+ /* clear grid info */
+ zero_v3_int(clmd->hair_grid_res);
+ zero_v3(clmd->hair_grid_min);
+ zero_v3(clmd->hair_grid_max);
+ clmd->hair_grid_cellsize = 0.0f;
+
+ hair_get_boundbox(clmd, gmin, gmax);
+
+ /* gather velocities & density */
+ if (smoothfac > 0.0f || density_strength > 0.0f) {
+ HairGrid *grid = BPH_hair_volume_create_vertex_grid(clmd->sim_parms->voxel_cell_size, gmin, gmax);
+
+ cloth_continuum_fill_grid(grid, cloth);
+
+ /* main hair continuum solver */
+ BPH_hair_volume_solve_divergence(grid, dt, density_target, density_strength);
+
+ for (i = 0, vert = cloth->verts; i < mvert_num; i++, vert++) {
+ float x[3], v[3], nv[3];
+
+ /* calculate volumetric velocity influence */
+ BPH_mass_spring_get_position(data, i, x);
+ BPH_mass_spring_get_new_velocity(data, i, v);
+
+ BPH_hair_volume_grid_velocity(grid, x, v, fluid_factor, nv);
+
+ interp_v3_v3v3(nv, v, nv, smoothfac);
+
+ /* apply on hair data */
+ BPH_mass_spring_set_new_velocity(data, i, nv);
+ }
+
+ /* store basic grid info in the modifier data */
+ BPH_hair_volume_grid_geometry(grid, &clmd->hair_grid_cellsize, clmd->hair_grid_res, clmd->hair_grid_min, clmd->hair_grid_max);
+
+#if 0 /* DEBUG hair velocity vector field */
+ {
+ const int size = 64;
+ int i, j;
+ float offset[3], a[3], b[3];
+ const int axis = 0;
+ const float shift = 0.0f;
+
+ copy_v3_v3(offset, clmd->hair_grid_min);
+ zero_v3(a);
+ zero_v3(b);
+
+ offset[axis] = shift * clmd->hair_grid_cellsize;
+ a[(axis+1) % 3] = clmd->hair_grid_max[(axis+1) % 3] - clmd->hair_grid_min[(axis+1) % 3];
+ b[(axis+2) % 3] = clmd->hair_grid_max[(axis+2) % 3] - clmd->hair_grid_min[(axis+2) % 3];
+
+ BKE_sim_debug_data_clear_category(clmd->debug_data, "grid velocity");
+ for (j = 0; j < size; ++j) {
+ for (i = 0; i < size; ++i) {
+ float x[3], v[3], gvel[3], gvel_smooth[3], gdensity;
+
+ madd_v3_v3v3fl(x, offset, a, (float)i / (float)(size-1));
+ madd_v3_v3fl(x, b, (float)j / (float)(size-1));
+ zero_v3(v);
+
+ BPH_hair_volume_grid_interpolate(grid, x, &gdensity, gvel, gvel_smooth, NULL, NULL);
+
+// BKE_sim_debug_data_add_circle(clmd->debug_data, x, gdensity, 0.7, 0.3, 1, "grid density", i, j, 3111);
+ if (!is_zero_v3(gvel) || !is_zero_v3(gvel_smooth)) {
+ float dvel[3];
+ sub_v3_v3v3(dvel, gvel_smooth, gvel);
+// BKE_sim_debug_data_add_vector(clmd->debug_data, x, gvel, 0.4, 0, 1, "grid velocity", i, j, 3112);
+// BKE_sim_debug_data_add_vector(clmd->debug_data, x, gvel_smooth, 0.6, 1, 1, "grid velocity", i, j, 3113);
+ BKE_sim_debug_data_add_vector(clmd->debug_data, x, dvel, 0.4, 1, 0.7, "grid velocity", i, j, 3114);
+#if 0
+ if (gdensity > 0.0f) {
+ float col0[3] = {0.0, 0.0, 0.0};
+ float col1[3] = {0.0, 1.0, 0.0};
+ float col[3];
+
+ interp_v3_v3v3(col, col0, col1, CLAMPIS(gdensity * clmd->sim_parms->density_strength, 0.0, 1.0));
+// BKE_sim_debug_data_add_circle(clmd->debug_data, x, gdensity * clmd->sim_parms->density_strength, 0, 1, 0.4, "grid velocity", i, j, 3115);
+// BKE_sim_debug_data_add_dot(clmd->debug_data, x, col[0], col[1], col[2], "grid velocity", i, j, 3115);
+ BKE_sim_debug_data_add_circle(clmd->debug_data, x, 0.01f, col[0], col[1], col[2], "grid velocity", i, j, 3115);
+ }
+#endif
+ }
+ }
+ }
+ }
+#endif
+
+ BPH_hair_volume_free_vertex_grid(grid);
+ }
+}
+
+#if 0
+static void cloth_calc_volume_force(ClothModifierData *clmd)
+{
+ ClothSimSettings *parms = clmd->sim_parms;
+ Cloth *cloth = clmd->clothObject;
+ Implicit_Data *data = cloth->implicit;
+ int mvert_num = cloth->mvert_num;
+ ClothVertex *vert;
+
+ /* 2.0f is an experimental value that seems to give good results */
+ float smoothfac = 2.0f * parms->velocity_smooth;
+ float collfac = 2.0f * parms->collider_friction;
+ float pressfac = parms->pressure;
+ float minpress = parms->pressure_threshold;
+ float gmin[3], gmax[3];
+ int i;
+
+ hair_get_boundbox(clmd, gmin, gmax);
+
+ /* gather velocities & density */
+ if (smoothfac > 0.0f || pressfac > 0.0f) {
+ HairVertexGrid *vertex_grid = BPH_hair_volume_create_vertex_grid(clmd->sim_parms->voxel_res, gmin, gmax);
+
+ vert = cloth->verts;
+ for (i = 0; i < mvert_num; i++, vert++) {
+ float x[3], v[3];
+
+ if (vert->solver_index < 0) {
+ copy_v3_v3(x, vert->x);
+ copy_v3_v3(v, vert->v);
+ }
+ else {
+ BPH_mass_spring_get_motion_state(data, vert->solver_index, x, v);
+ }
+ BPH_hair_volume_add_vertex(vertex_grid, x, v);
+ }
+ BPH_hair_volume_normalize_vertex_grid(vertex_grid);
+
+ vert = cloth->verts;
+ for (i = 0; i < mvert_num; i++, vert++) {
+ float x[3], v[3], f[3], dfdx[3][3], dfdv[3][3];
+
+ if (vert->solver_index < 0)
+ continue;
+
+ /* calculate volumetric forces */
+ BPH_mass_spring_get_motion_state(data, vert->solver_index, x, v);
+ BPH_hair_volume_vertex_grid_forces(vertex_grid, x, v, smoothfac, pressfac, minpress, f, dfdx, dfdv);
+ /* apply on hair data */
+ BPH_mass_spring_force_extern(data, vert->solver_index, f, dfdx, dfdv);
+ }
+
+ BPH_hair_volume_free_vertex_grid(vertex_grid);
+ }
+}
+#endif
+
+/* old collision stuff for cloth, use for continuity
+ * until a good replacement is ready
+ */
+static void cloth_collision_solve_extra(Object *ob, ClothModifierData *clmd, ListBase *effectors, float frame, float step, float dt)
+{
+ Cloth *cloth = clmd->clothObject;
+ Implicit_Data *id = cloth->implicit;
+ ClothVertex *verts = cloth->verts;
+ int mvert_num = cloth->mvert_num;
+ const float spf = (float)clmd->sim_parms->stepsPerFrame / clmd->sim_parms->timescale;
+
+ bool do_extra_solve;
+ int i;
+
+ if (!(clmd->coll_parms->flags & CLOTH_COLLSETTINGS_FLAG_ENABLED))
+ return;
+ if (!clmd->clothObject->bvhtree)
+ return;
+
+ // update verts to current positions
+ for (i = 0; i < mvert_num; i++) {
+ BPH_mass_spring_get_new_position(id, i, verts[i].tx);
+
+ sub_v3_v3v3(verts[i].tv, verts[i].tx, verts[i].txold);
+ copy_v3_v3(verts[i].v, verts[i].tv);
+ }
+
+#if 0 /* unused */
+ for (i=0, cv=cloth->verts; i<cloth->mvert_num; i++, cv++) {
+ copy_v3_v3(initial_cos[i], cv->tx);
+ }
+#endif
+
+ // call collision function
+ // TODO: check if "step" or "step+dt" is correct - dg
+ do_extra_solve = cloth_bvh_objcollision(ob, clmd, step / clmd->sim_parms->timescale, dt / clmd->sim_parms->timescale);
+
+ // copy corrected positions back to simulation
+ for (i = 0; i < mvert_num; i++) {
+ float curx[3];
+ BPH_mass_spring_get_position(id, i, curx);
+ // correct velocity again, just to be sure we had to change it due to adaptive collisions
+ sub_v3_v3v3(verts[i].tv, verts[i].tx, curx);
+ }
+
+ if (do_extra_solve) {
+// cloth_calc_helper_forces(ob, clmd, initial_cos, step/clmd->sim_parms->timescale, dt/clmd->sim_parms->timescale);
+
+ for (i = 0; i < mvert_num; i++) {
+
+ float newv[3];
+
+ if ((clmd->sim_parms->flags & CLOTH_SIMSETTINGS_FLAG_GOAL) && (verts [i].flags & CLOTH_VERT_FLAG_PINNED))
+ continue;
+
+ BPH_mass_spring_set_new_position(id, i, verts[i].tx);
+ mul_v3_v3fl(newv, verts[i].tv, spf);
+ BPH_mass_spring_set_new_velocity(id, i, newv);
+ }
+ }
+
+ // X = Xnew;
+ BPH_mass_spring_apply_result(id);
+
+ if (do_extra_solve) {
+ ImplicitSolverResult result;
+
+ /* initialize forces to zero */
+ BPH_mass_spring_clear_forces(id);
+
+ // calculate forces
+ cloth_calc_force(clmd, frame, effectors, step);
+
+ // calculate new velocity and position
+ BPH_mass_spring_solve_velocities(id, dt, &result);
+// cloth_record_result(clmd, &result, clmd->sim_parms->stepsPerFrame);
+
+ /* note: positions are advanced only once in the main solver step! */
+
+ BPH_mass_spring_apply_result(id);
+ }
+}
+
+static void cloth_clear_result(ClothModifierData *clmd)
+{
+ ClothSolverResult *sres = clmd->solver_result;
+
+ sres->status = 0;
+ sres->max_error = sres->min_error = sres->avg_error = 0.0f;
+ sres->max_iterations = sres->min_iterations = 0;
+ sres->avg_iterations = 0.0f;
+}
+
+static void cloth_record_result(ClothModifierData *clmd, ImplicitSolverResult *result, int steps)
+{
+ ClothSolverResult *sres = clmd->solver_result;
+
+ if (sres->status) { /* already initialized ? */
+ /* error only makes sense for successful iterations */
+ if (result->status == BPH_SOLVER_SUCCESS) {
+ sres->min_error = min_ff(sres->min_error, result->error);
+ sres->max_error = max_ff(sres->max_error, result->error);
+ sres->avg_error += result->error / (float)steps;
+ }
+
+ sres->min_iterations = min_ii(sres->min_iterations, result->iterations);
+ sres->max_iterations = max_ii(sres->max_iterations, result->iterations);
+ sres->avg_iterations += (float)result->iterations / (float)steps;
+ }
+ else {
+ /* error only makes sense for successful iterations */
+ if (result->status == BPH_SOLVER_SUCCESS) {
+ sres->min_error = sres->max_error = result->error;
+ sres->avg_error += result->error / (float)steps;
+ }
+
+ sres->min_iterations = sres->max_iterations = result->iterations;
+ sres->avg_iterations += (float)result->iterations / (float)steps;
+ }
+
+ sres->status |= result->status;
+}
+
+int BPH_cloth_solve(Object *ob, float frame, ClothModifierData *clmd, ListBase *effectors)
+{
+ /* Hair currently is a cloth sim in disguise ...
+ * Collision detection and volumetrics work differently then.
+ * Bad design, TODO
+ */
+ const bool is_hair = (clmd->hairdata != NULL);
+
+ unsigned int i=0;
+ float step=0.0f, tf=clmd->sim_parms->timescale;
+ Cloth *cloth = clmd->clothObject;
+ ClothVertex *verts = cloth->verts/*, *cv*/;
+ unsigned int mvert_num = cloth->mvert_num;
+ float dt = clmd->sim_parms->timescale / clmd->sim_parms->stepsPerFrame;
+ Implicit_Data *id = cloth->implicit;
+ ColliderContacts *contacts = NULL;
+ int totcolliders = 0;
+
+ BKE_sim_debug_data_clear_category("collision");
+
+ if (!clmd->solver_result)
+ clmd->solver_result = (ClothSolverResult *)MEM_callocN(sizeof(ClothSolverResult), "cloth solver result");
+ cloth_clear_result(clmd);
+
+ if (clmd->sim_parms->flags & CLOTH_SIMSETTINGS_FLAG_GOAL) { /* do goal stuff */
+ for (i = 0; i < mvert_num; i++) {
+ // update velocities with constrained velocities from pinned verts
+ if (verts[i].flags & CLOTH_VERT_FLAG_PINNED) {
+ float v[3];
+ sub_v3_v3v3(v, verts[i].xconst, verts[i].xold);
+ // mul_v3_fl(v, clmd->sim_parms->stepsPerFrame);
+ BPH_mass_spring_set_velocity(id, i, v);
+ }
+ }
+ }
+
+ while (step < tf) {
+ ImplicitSolverResult result;
+
+ /* copy velocities for collision */
+ for (i = 0; i < mvert_num; i++) {
+ BPH_mass_spring_get_motion_state(id, i, NULL, verts[i].tv);
+ copy_v3_v3(verts[i].v, verts[i].tv);
+ }
+
+ if (is_hair) {
+ /* determine contact points */
+ if (clmd->coll_parms->flags & CLOTH_COLLSETTINGS_FLAG_ENABLED) {
+ cloth_find_point_contacts(ob, clmd, 0.0f, tf, &contacts, &totcolliders);
+ }
+
+ /* setup vertex constraints for pinned vertices and contacts */
+ cloth_setup_constraints(clmd, contacts, totcolliders, dt);
+ }
+ else {
+ /* setup vertex constraints for pinned vertices */
+ cloth_setup_constraints(clmd, NULL, 0, dt);
+ }
+
+ /* initialize forces to zero */
+ BPH_mass_spring_clear_forces(id);
+
+ // damping velocity for artistic reasons
+ // this is a bad way to do it, should be removed imo - lukas_t
+ if (clmd->sim_parms->vel_damping != 1.0f) {
+ for (i = 0; i < mvert_num; i++) {
+ float v[3];
+ BPH_mass_spring_get_motion_state(id, i, NULL, v);
+ mul_v3_fl(v, clmd->sim_parms->vel_damping);
+ BPH_mass_spring_set_velocity(id, i, v);
+ }
+ }
+
+ // calculate forces
+ cloth_calc_force(clmd, frame, effectors, step);
+
+ // calculate new velocity and position
+ BPH_mass_spring_solve_velocities(id, dt, &result);
+ cloth_record_result(clmd, &result, clmd->sim_parms->stepsPerFrame);
+
+ if (is_hair) {
+ cloth_continuum_step(clmd, dt);
+ }
+
+ BPH_mass_spring_solve_positions(id, dt);
+
+ if (!is_hair) {
+ cloth_collision_solve_extra(ob, clmd, effectors, frame, step, dt);
+ }
+
+ BPH_mass_spring_apply_result(id);
+
+ /* move pinned verts to correct position */
+ for (i = 0; i < mvert_num; i++) {
+ if (clmd->sim_parms->flags & CLOTH_SIMSETTINGS_FLAG_GOAL) {
+ if (verts[i].flags & CLOTH_VERT_FLAG_PINNED) {
+ float x[3];
+ interp_v3_v3v3(x, verts[i].xold, verts[i].xconst, step + dt);
+ BPH_mass_spring_set_position(id, i, x);
+ }
+ }
+
+ BPH_mass_spring_get_motion_state(id, i, verts[i].txold, NULL);
+ }
+
+ /* free contact points */
+ if (contacts) {
+ cloth_free_contacts(contacts, totcolliders);
+ }
+
+ step += dt;
+ }
+
+ /* copy results back to cloth data */
+ for (i = 0; i < mvert_num; i++) {
+ BPH_mass_spring_get_motion_state(id, i, verts[i].x, verts[i].v);
+ copy_v3_v3(verts[i].txold, verts[i].x);
+ }
+
+ return 1;
+}
+
+bool BPH_cloth_solver_get_texture_data(Object *UNUSED(ob), ClothModifierData *clmd, VoxelData *vd)
+{
+ Cloth *cloth = clmd->clothObject;
+ HairGrid *grid;
+ float gmin[3], gmax[3];
+
+ if (!clmd->clothObject || !clmd->clothObject->implicit)
+ return false;
+
+ hair_get_boundbox(clmd, gmin, gmax);
+
+ grid = BPH_hair_volume_create_vertex_grid(clmd->sim_parms->voxel_cell_size, gmin, gmax);
+ cloth_continuum_fill_grid(grid, cloth);
+
+ BPH_hair_volume_get_texture_data(grid, vd);
+
+ BPH_hair_volume_free_vertex_grid(grid);
+
+ return true;
+}
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