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Partial response force for hair collisions.

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This implements a penalty force as well as a repulsion force to avoid
further penetration, as suggested in
"Simulating Complex Hair with Robust Collision Handling"
(http://graphics.snu.ac.kr/publications/2005-choe-HairSim/Choe_2005_SCA.pdf)

Friction forces are still missing. More problematic is handling of
moving colliders, when face swap places with the hair vertex and a
collision is missed, putting the vertex inside the mesh volume. Larger
margins might help, but ultimately using Bullet collision detection is
probably more reliable and failsafe.
This commit is contained in:
Lukas Tönne
2014-09-01 17:46:17 +02:00
parent d8cf12fe5a
commit 1ed88bb24e
6 changed files with 170 additions and 58 deletions
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1
source/blender/blenkernel/BKE_effect.h
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@@ -160,6 +160,7 @@ struct SimDebugData *BKE_sim_debug_data_new(void);
void BKE_sim_debug_data_add_dot(struct SimDebugData *debug_data, const float p[3], float r, float g, float b, int hash);
void BKE_sim_debug_data_add_line(struct SimDebugData *debug_data, const float p1[3], const float p2[3], float r, float g, float b, int hash);
void BKE_sim_debug_data_add_vector(struct SimDebugData *debug_data, const float p[3], const float d[3], float r, float g, float b, int hash);
void BKE_sim_debug_data_remove(struct SimDebugData *debug_data, int hash);
void BKE_sim_debug_data_clear(struct SimDebugData *debug_data);
void BKE_sim_debug_data_free(struct SimDebugData *debug_data);

183
source/blender/blenkernel/intern/collision.c
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@@ -33,6 +33,7 @@
#include "MEM_guardedalloc.h"
#include "DNA_cloth_types.h"
#include "DNA_effect_types.h"
#include "DNA_group_types.h"
#include "DNA_object_types.h"
#include "DNA_object_force.h"
@@ -45,6 +46,7 @@
#include "BLI_edgehash.h"
#include "BKE_cloth.h"
#include "BKE_effect.h"
#include "BKE_modifier.h"
#include "BKE_scene.h"
@@ -59,6 +61,41 @@
#endif
/* ==== hash functions for debugging ==== */
static unsigned int hash_int_2d(unsigned int kx, unsigned int ky)
{
#define rot(x,k) (((x)<<(k)) | ((x)>>(32-(k))))
unsigned int a, b, c;
a = b = c = 0xdeadbeef + (2 << 2) + 13;
a += kx;
b += ky;
c ^= b; c -= rot(b,14);
a ^= c; a -= rot(c,11);
b ^= a; b -= rot(a,25);
c ^= b; c -= rot(b,16);
a ^= c; a -= rot(c,4);
b ^= a; b -= rot(a,14);
c ^= b; c -= rot(b,24);
return c;
#undef rot
}
static int hash_vertex(int type, int vertex)
{
return hash_int_2d((unsigned int)type, (unsigned int)vertex);
}
static int hash_collpair(int type, CollPair *collpair)
{
return hash_int_2d((unsigned int)type, hash_int_2d((unsigned int)collpair->face1, (unsigned int)collpair->face2));
}
/* ================ */
/***********************************
Collision modifier code start
***********************************/
@@ -914,24 +951,35 @@ int cloth_bvh_objcollision(Object *ob, ClothModifierData *clmd, float step, floa
return 1|MIN2 ( ret, 1 );
}
static int cloth_points_collision_response_static(ClothModifierData *clmd, CollisionModifierData *collmd, CollPair *collpair, CollPair *collision_end)
BLI_INLINE void max_v3_v3v3(float r[3], const float a[3], const float b[3])
{
int result = 0;
Cloth *cloth1;
r[0] = max_ff(a[0], b[0]);
r[1] = max_ff(a[1], b[1]);
r[2] = max_ff(a[2], b[2]);
}
static bool cloth_points_collision_response_static(ClothModifierData *clmd, CollisionModifierData *collmd, PartDeflect *pd,
CollPair *collpair, CollPair *collision_end, float dt)
{
bool result = false;
float restitution = (1.0f - clmd->coll_parms->damping) * (1.0f - pd->pdef_sbdamp);
float inv_dt = 1.0f / dt;
Cloth *cloth1 = clmd->clothObject;
float w1, w2, u1, u2, u3;
float v1[3], v2[3], relativeVelocity[3];
float magrelVel;
float v1[3], v2_old[3], v2_new[3], v_rel_old[3], v_rel_new[3];
// float magrelVel;
float epsilon2 = BLI_bvhtree_getepsilon ( collmd->bvhtree );
cloth1 = clmd->clothObject;
for ( ; collpair != collision_end; collpair++ ) {
// float i1[3], i2[3], i3[3];
float margin_distance = collpair->distance - epsilon2;
float impulse[3];
float mag_v_rel;
// zero_v3(i1);
// zero_v3(i2);
// zero_v3(i3);
if (margin_distance > 0.0f)
continue;
zero_v3(impulse);
/* only handle static collisions here */
if ( collpair->flag & COLLISION_IN_FUTURE )
@@ -951,17 +999,75 @@ static int cloth_points_collision_response_static(ClothModifierData *clmd, Colli
/* Calculate relative velocity */
copy_v3_v3(v1, cloth1->verts[collpair->ap1].tv);
collision_interpolateOnTriangle ( v2, collmd->current_v[collpair->bp1].co, collmd->current_v[collpair->bp2].co, collmd->current_v[collpair->bp3].co, u1, u2, u3 );
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 );
/* XXX assume constant velocity of the collider for now */
copy_v3_v3(v2_old, v2_new);
sub_v3_v3v3(relativeVelocity, v2, v1);
sub_v3_v3v3(v_rel_old, v1, v2_old);
sub_v3_v3v3(v_rel_new, v1, v2_new);
/* Calculate the normal component of the relative velocity (actually only the magnitude - the direction is stored in 'normal'). */
magrelVel = dot_v3v3(relativeVelocity, collpair->normal);
/* normal component of the relative velocity */
mag_v_rel = dot_v3v3(v_rel_old, collpair->normal);
/* printf("magrelVel: %f\n", magrelVel); */
/**** DEBUG ****/
if (clmd->debug_data) {
BKE_sim_debug_data_add_dot(clmd->debug_data, collpair->pa, 0.9, 0.2, 0.2, hash_collpair(833, collpair));
BKE_sim_debug_data_add_dot(clmd->debug_data, collpair->pb, 0.2, 0.9, 0.2, hash_collpair(834, collpair));
BKE_sim_debug_data_add_line(clmd->debug_data, collpair->pa, collpair->pb, 0.8, 0.8, 0.8, hash_collpair(835, collpair));
BKE_sim_debug_data_add_vector(clmd->debug_data, collpair->pa, collpair->normal, 1.0, 1.0, 0.0, hash_collpair(836, collpair));
}
/********/
/* Calculate masses of points.
* TODO */
if (mag_v_rel < -ALMOST_ZERO) {
float v_nor_old, v_nor_new;
float v_tan_old[3], v_tan_new[3];
float repulse[3];
/* 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);
mul_v3_v3fl(repulse, collpair->normal, -margin_distance * inv_dt);
sub_v3_v3(repulse, v1);
// if (margin_distance < -epsilon2) {
{
float bounce[3];
mul_v3_v3fl(bounce, collpair->normal, -(v_nor_new + v_nor_old * restitution));
// max_v3_v3v3(impulse, repulse, bounce);
copy_v3_v3(impulse, bounce);
}
// else {
// copy_v3_v3(impulse, repulse);
// }
cloth1->verts[collpair->ap1].impulse_count++;
BKE_sim_debug_data_add_vector(clmd->debug_data, collpair->pa, impulse, 0.0, 1.0, 0.6, hash_collpair(873, collpair));
result = true;
}
else {
BKE_sim_debug_data_remove(clmd->debug_data, hash_collpair(833, collpair));
BKE_sim_debug_data_remove(clmd->debug_data, hash_collpair(834, collpair));
BKE_sim_debug_data_remove(clmd->debug_data, hash_collpair(835, collpair));
BKE_sim_debug_data_remove(clmd->debug_data, hash_collpair(873, collpair));
}
if (result) {
int i = 0;
for (i = 0; i < 3; i++) {
if (cloth1->verts[collpair->ap1].impulse_count > 0 && fabsf(cloth1->verts[collpair->ap1].impulse[i]) < fabsf(impulse[i]))
cloth1->verts[collpair->ap1].impulse[i] = impulse[i];
}
}
#if 0
/* If v_n_mag < 0 the edges are approaching each other. */
@@ -1163,7 +1269,8 @@ static void cloth_points_objcollisions_nearcheck(ClothModifierData * clmd, Colli
}
}
static int cloth_points_objcollisions_resolve ( ClothModifierData * clmd, CollisionModifierData *collmd, CollPair *collisions, CollPair *collisions_index)
static int cloth_points_objcollisions_resolve(ClothModifierData * clmd, CollisionModifierData *collmd, PartDeflect *pd,
CollPair *collisions, CollPair *collisions_index, float dt)
{
Cloth *cloth = clmd->clothObject;
int i=0, numverts = clmd->clothObject->numverts;
@@ -1172,7 +1279,7 @@ static int cloth_points_objcollisions_resolve ( ClothModifierData * clmd, Collis
// process all collisions
if ( collmd->bvhtree ) {
int result = cloth_points_collision_response_static(clmd, collmd, collisions, collisions_index);
bool result = cloth_points_collision_response_static(clmd, collmd, pd, collisions, collisions_index, dt);
// apply impulses in parallel
if (result) {
@@ -1189,36 +1296,6 @@ static int cloth_points_objcollisions_resolve ( ClothModifierData * clmd, Collis
}
}
}
#if 0
// process all collisions (calculate impulses, TODO: also repulses if distance too short)
result = 1;
for ( j = 0; j < 2; j++ ) { /* 5 is just a value that ensures convergence */
result = 0;
if ( collmd->bvhtree ) {
result += cloth_points_collision_response_static(clmd, collmd, collisions, collisions_index);
// apply impulses in parallel
if (result) {
for (i = 0; i < numverts; i++) {
// calculate "velocities" (just xnew = xold + v; no dt in v)
if (verts[i].impulse_count) {
// VECADDMUL ( verts[i].tv, verts[i].impulse, 1.0f / verts[i].impulse_count );
VECADD ( verts[i].tv, verts[i].tv, verts[i].impulse);
zero_v3(verts[i].impulse);
verts[i].impulse_count = 0;
ret++;
}
}
}
}
if (!result) {
break;
}
}
#endif
return ret;
}
@@ -1244,7 +1321,7 @@ int cloth_points_objcollision(Object *ob, ClothModifierData *clmd, float step, f
////////////////////////////////////////////////////////////
// create temporary cloth points bvh
cloth_bvh = BLI_bvhtree_new(numverts, MAX2(clmd->coll_parms->epsilon, clmd->coll_parms->distance_repel), 2, 26);
cloth_bvh = BLI_bvhtree_new(numverts, MAX2(clmd->coll_parms->epsilon, clmd->coll_parms->distance_repel), 4, 6);
/* fill tree */
for (i = 0; i < numverts; i++) {
float co[6];
@@ -1300,7 +1377,7 @@ int cloth_points_objcollision(Object *ob, ClothModifierData *clmd, float step, f
result, overlap, round_dt);
// resolve nearby collisions
ret += cloth_points_objcollisions_resolve(clmd, collmd, collisions[i], collisions_index[i]);
ret += cloth_points_objcollisions_resolve(clmd, collmd, collob->pd, collisions[i], collisions_index[i], round_dt);
ret2 += ret;
}

28
source/blender/blenkernel/intern/effect.c
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@@ -1072,7 +1072,11 @@ static void debug_data_insert(SimDebugData *debug_data, SimDebugElement *elem)
void BKE_sim_debug_data_add_dot(struct SimDebugData *debug_data, const float p[3], float r, float g, float b, int hash)
{
SimDebugElement *elem = MEM_callocN(sizeof(SimDebugElement), "sim debug data element");
SimDebugElement *elem;
if (!debug_data)
return;
elem = MEM_callocN(sizeof(SimDebugElement), "sim debug data element");
elem->type = SIM_DEBUG_ELEM_DOT;
elem->hash = hash;
elem->color[0] = r;
@@ -1085,7 +1089,11 @@ void BKE_sim_debug_data_add_dot(struct SimDebugData *debug_data, const float p[3
void BKE_sim_debug_data_add_line(struct SimDebugData *debug_data, const float p1[3], const float p2[3], float r, float g, float b, int hash)
{
SimDebugElement *elem = MEM_callocN(sizeof(SimDebugElement), "sim debug data element");
SimDebugElement *elem;
if (!debug_data)
return;
elem = MEM_callocN(sizeof(SimDebugElement), "sim debug data element");
elem->type = SIM_DEBUG_ELEM_LINE;
elem->hash = hash;
elem->color[0] = r;
@@ -1099,7 +1107,11 @@ void BKE_sim_debug_data_add_line(struct SimDebugData *debug_data, const float p1
void BKE_sim_debug_data_add_vector(struct SimDebugData *debug_data, const float p[3], const float d[3], float r, float g, float b, int hash)
{
SimDebugElement *elem = MEM_callocN(sizeof(SimDebugElement), "sim debug data element");
SimDebugElement *elem;
if (!debug_data)
return;
elem = MEM_callocN(sizeof(SimDebugElement), "sim debug data element");
elem->type = SIM_DEBUG_ELEM_VECTOR;
elem->hash = hash;
elem->color[0] = r;
@@ -1111,6 +1123,16 @@ void BKE_sim_debug_data_add_vector(struct SimDebugData *debug_data, const float
debug_data_insert(debug_data, elem);
}
void BKE_sim_debug_data_remove(SimDebugData *debug_data, int hash)
{
SimDebugElement dummy;
if (!debug_data)
return;
dummy.hash = hash;
BLI_ghash_remove(debug_data->gh, &dummy, NULL, debug_element_free);
}
void BKE_sim_debug_data_clear(SimDebugData *debug_data)
{
if (!debug_data)

4
source/blender/blenloader/intern/readfile.c
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@@ -113,6 +113,7 @@
#include "BKE_armature.h"
#include "BKE_brush.h"
#include "BKE_cloth.h"
#include "BKE_constraint.h"
#include "BKE_context.h"
#include "BKE_curve.h"
@@ -3940,6 +3941,9 @@ static void direct_link_particlesystems(FileData *fd, ListBase *particles)
if (psys->clmd->sim_parms->presets > 10)
psys->clmd->sim_parms->presets = 0;
}
if (psys->clmd->coll_parms) {
psys->clmd->coll_parms->flags |= CLOTH_COLLSETTINGS_FLAG_POINTS;
}
psys->hair_in_dm = psys->hair_out_dm = NULL;

5
source/blender/makesdna/DNA_cloth_types.h
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@@ -99,15 +99,16 @@ typedef struct ClothCollSettings {
float epsilon; /* min distance for collisions. */
float self_friction; /* Fiction/damping with self contact. */
float friction; /* Friction/damping applied on contact with other object.*/
float damping; /* Collision restitution on contact with other object.*/
float selfepsilon; /* for selfcollision */
float repel_force, distance_repel;
int flags; /* collision flags defined in BKE_cloth.h */
short self_loop_count; /* How many iterations for the selfcollision loop */
short loop_count; /* How many iterations for the collision loop. */
int pad;
struct Group *group; /* Only use colliders from this group of objects */
short vgroup_selfcol; /* vgroup to paint which vertices are used for self collisions */
short pad;
int pad2;
short pad2[3];
} ClothCollSettings;

7
source/blender/makesrna/intern/rna_cloth.c
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@@ -589,6 +589,13 @@ static void rna_def_cloth_collision_settings(BlenderRNA *brna)
RNA_def_property_ui_text(prop, "Friction", "Friction force if a collision happened (higher = less movement)");
RNA_def_property_update(prop, 0, "rna_cloth_update");
prop = RNA_def_property(srna, "damping", PROP_FLOAT, PROP_FACTOR);
RNA_def_property_float_sdna(prop, NULL, "damping");
RNA_def_property_range(prop, 0.0f, 1.0f);
RNA_def_property_float_default(prop, 1.0f);
RNA_def_property_ui_text(prop, "Restitution", "Amount of velocity lost on collision");
RNA_def_property_update(prop, 0, "rna_cloth_update");
prop = RNA_def_property(srna, "collision_quality", PROP_INT, PROP_NONE);
RNA_def_property_int_sdna(prop, NULL, "loop_count");
RNA_def_property_range(prop, 1, 20);