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Fixed voxel grid initialization from hair points and colliders by using

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the suggested tent function from the original paper.

Plain float->int conversion for the grid location otherwise leads to
skewed data and unnecessary loss of information.
This commit is contained in:
Lukas Tönne
2014-08-27 12:30:25 +02:00
parent 5f41b19463
commit efc0cd1658
1 changed files with 113 additions and 50 deletions
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163
source/blender/blenkernel/intern/implicit.c
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@@ -1218,6 +1218,12 @@ static float calculateVertexWindForce(const float wind[3], const float vertexnor
* Pixar Technical Memo #06-08, Pixar Animation Studios
*/
/* Note about array indexing:
* Generally the arrays here are one-dimensional.
* The relation between 3D indices and the array offset is
* offset = x + res_x * y + res_y * z
*/
/* TODO: This is an initial implementation and should be made much better in due time.
* What should at least be implemented is a grid size parameter and a smoothing kernel
* for bigger grids.
@@ -1231,43 +1237,49 @@ static int hair_grid_size(int res)
return res * res * res;
}
BLI_INLINE void hair_grid_get_scale(int res, const float gmin[3], const float gmax[3], float scale[3])
{
sub_v3_v3v3(scale, gmax, gmin);
mul_v3_fl(scale, 1.0f / (res-1));
}
typedef struct HairGridVert {
float velocity[3];
float density;
} HairGridVert;
#define HAIR_GRID_INDEX_AXIS(vec, min, max, axis) (int)((vec[axis] - min[axis]) / (max[axis] - min[axis]) * 9.99f)
#define HAIR_GRID_INDEX_AXIS(vec, res, gmin, scale, axis) ( min_ii( max_ii( (int)((vec[axis] - gmin[axis]) / scale[axis]), 0), res-2 ) )
#if 0
BLI_INLINE void hair_grid_index(lfVector *vec, int res, const float min[3], const float max[3],
float *r_i, float *r_j, float *r_k, float *r_offset)
{
*r_i = HAIR_GRID_INDEX_AXIS(vec, min, max, 0);
*r_j = HAIR_GRID_INDEX_AXIS(vec, min, max, 1);
*r_k = HAIR_GRID_INDEX_AXIS(vec, min, max, 2);
*r_offset = i + (j + k*res)*res;
}
#endif
BLI_INLINE int hair_grid_offset(const float vec[3], int res, const float min[3], const float max[3])
BLI_INLINE int hair_grid_offset(const float vec[3], int res, const float gmin[3], const float scale[3])
{
int i, j, k;
i = HAIR_GRID_INDEX_AXIS(vec, min, max, 0);
j = HAIR_GRID_INDEX_AXIS(vec, min, max, 1);
k = HAIR_GRID_INDEX_AXIS(vec, min, max, 2);
i = HAIR_GRID_INDEX_AXIS(vec, res, gmin, scale, 0);
j = HAIR_GRID_INDEX_AXIS(vec, res, gmin, scale, 1);
k = HAIR_GRID_INDEX_AXIS(vec, res, gmin, scale, 2);
return i + (j + k*res)*res;
}
static void hair_velocity_smoothing(const HairGridVert *hairgrid, const float gmin[3], const float gmax[3], float smoothfac,
BLI_INLINE void hair_grid_vertex_loc(int offset, int res, const float gmin[3], const float scale[3], float loc[3])
{
int v = offset;
float ijk[3];
ijk[0] = (float)(v % res);
v /= res;
ijk[1] = (float)(v % res);
v /= res;
ijk[2] = (float)(v % res);
madd_v3_v3v3v3(loc, gmin, ijk, scale);
}
static void hair_velocity_smoothing(const HairGridVert *hairgrid, const float gmin[3], const float scale[3], float smoothfac,
lfVector *lF, lfVector *lX, lfVector *lV, unsigned int numverts)
{
int size = hair_grid_size(hair_grid_res);
int v;
/* calculate forces */
for (v = 0; v < numverts; v++) {
int offset = hair_grid_offset(lX[v], hair_grid_res, gmin, gmax);
if (offset < 0 || offset >= size)
continue;
int offset = hair_grid_offset(lX[v], hair_grid_res, gmin, scale);
lF[v][0] += smoothfac * (hairgrid[offset].velocity[0] - lV[v][0]);
lF[v][1] += smoothfac * (hairgrid[offset].velocity[1] - lV[v][1]);
@@ -1275,16 +1287,13 @@ static void hair_velocity_smoothing(const HairGridVert *hairgrid, const float gm
}
}
static void hair_velocity_collision(const HairGridVert *collgrid, const float gmin[3], const float gmax[3], float collfac,
static void hair_velocity_collision(const HairGridVert *collgrid, const float gmin[3], const float scale[3], float collfac,
lfVector *lF, lfVector *lX, lfVector *lV, unsigned int numverts)
{
int size = hair_grid_size(hair_grid_res);
int v;
/* calculate forces */
for (v = 0; v < numverts; v++) {
int offset = hair_grid_offset(lX[v], hair_grid_res, gmin, gmax);
if (offset < 0 || offset >= size)
continue;
int offset = hair_grid_offset(lX[v], hair_grid_res, gmin, scale);
if (collgrid[offset].density > 0.0f) {
lF[v][0] += collfac * (collgrid[offset].velocity[0] - lV[v][0]);
@@ -1303,17 +1312,46 @@ static void hair_volume_get_boundbox(lfVector *lX, unsigned int numverts, float
DO_MINMAX(lX[i], gmin, gmax);
}
BLI_INLINE bool hair_grid_point_valid(const float vec[3], float gmin[3], float gmax[3])
{
return !(vec[0] < gmin[0] || vec[1] < gmin[1] || vec[2] < gmin[2] ||
vec[0] > gmax[0] || vec[1] > gmax[1] || vec[2] > gmax[2]);
}
BLI_INLINE float dist_tent_v3f3(const float a[3], float x, float y, float z)
{
return (1.0f - fabsf(a[0] - x)) * (1.0f - fabsf(a[1] - y)) * (1.0f - fabsf(a[2] - z));
}
static void hair_grid_weights(int res, const float gmin[3], const float scale[3], const float vec[3], int offset, float weights[8])
{
float vloc[3];
hair_grid_vertex_loc(offset, res, gmin, scale, vloc);
weights[0] = dist_tent_v3f3(vec, vloc[0], vloc[1], vloc[2] );
weights[1] = dist_tent_v3f3(vec, vloc[0] + scale[0], vloc[1], vloc[2] );
weights[2] = dist_tent_v3f3(vec, vloc[0], vloc[1] + scale[1], vloc[2] );
weights[3] = dist_tent_v3f3(vec, vloc[0] + scale[0], vloc[1] + scale[1], vloc[2] );
weights[4] = dist_tent_v3f3(vec, vloc[0], vloc[1], vloc[2] + scale[2]);
weights[5] = dist_tent_v3f3(vec, vloc[0] + scale[0], vloc[1], vloc[2] + scale[2]);
weights[6] = dist_tent_v3f3(vec, vloc[0], vloc[1] + scale[1], vloc[2] + scale[2]);
weights[7] = dist_tent_v3f3(vec, vloc[0] + scale[0], vloc[1] + scale[1], vloc[2] + scale[2]);
}
static HairGridVert *hair_volume_create_hair_grid(ClothModifierData *clmd, lfVector *lX, lfVector *lV, unsigned int numverts)
{
int size = hair_grid_size(hair_grid_res);
int res = hair_grid_res;
int size = hair_grid_size(res);
HairGridVert *hairgrid;
float gmin[3], gmax[3], density;
float gmin[3], gmax[3], scale[3];
/* 2.0f is an experimental value that seems to give good results */
float smoothfac = 2.0f * clmd->sim_parms->velocity_smooth;
unsigned int v = 0;
int i = 0;
hair_volume_get_boundbox(lX, numverts, gmin, gmax);
hair_grid_get_scale(res, gmin, gmax, scale);
hairgrid = MEM_mallocN(sizeof(HairGridVert) * size, "hair voxel data");
@@ -1326,23 +1364,35 @@ static HairGridVert *hair_volume_create_hair_grid(ClothModifierData *clmd, lfVec
/* gather velocities & density */
if (smoothfac > 0.0f) {
for (v = 0; v < numverts; v++) {
int offset = hair_grid_offset(lX[v], hair_grid_res, gmin, gmax);
if (offset < 0 || offset >= size)
float *V = lV[v];
float weights[8];
int di, dj, dk;
int offset = hair_grid_offset(lX[v], res, gmin, scale);
if (!hair_grid_point_valid(lX[v], gmin, gmax))
continue;
add_v3_v3(hairgrid[offset].velocity, lV[v]);
hairgrid[offset].density += 1.0f;
hair_grid_weights(res, gmin, scale, lX[v], offset, weights);
for (di = 0; di < 2; ++di) {
for (dj = 0; dj < 2; ++dj) {
for (dk = 0; dk < 2; ++dk) {
int voffset = offset + di + (dj + dk*res)*res;
int iw = di + dj*2 + dk*4;
hairgrid[voffset].density += weights[iw];
madd_v3_v3fl(hairgrid[voffset].velocity, V, weights[iw]);
}
}
}
}
}
/* divide velocity with density */
for (i = 0; i < size; i++) {
density = hairgrid[i].density;
if (density > 0.0f) {
hairgrid[i].velocity[0] /= density;
hairgrid[i].velocity[1] /= density;
hairgrid[i].velocity[2] /= density;
}
float density = hairgrid[i].density;
if (density > 0.0f)
mul_v3_fl(hairgrid[i].velocity, 1.0f/density);
}
return hairgrid;
@@ -1351,17 +1401,19 @@ static HairGridVert *hair_volume_create_hair_grid(ClothModifierData *clmd, lfVec
static HairGridVert *hair_volume_create_collision_grid(ClothModifierData *clmd, lfVector *lX, unsigned int numverts)
{
int size = hair_grid_size(hair_grid_res);
int res = hair_grid_res;
int size = hair_grid_size(res);
HairGridVert *collgrid;
ListBase *colliders;
ColliderCache *col = NULL;
float gmin[3], gmax[3], density;
float gmin[3], gmax[3], scale[3];
/* 2.0f is an experimental value that seems to give good results */
float collfac = 2.0f * clmd->sim_parms->collider_friction;
unsigned int v = 0;
int i = 0;
hair_volume_get_boundbox(lX, numverts, gmin, gmax);
hair_grid_get_scale(res, gmin, gmax, scale);
collgrid = MEM_mallocN(sizeof(HairGridVert) * size, "hair collider voxel data");
@@ -1378,16 +1430,30 @@ static HairGridVert *hair_volume_create_collision_grid(ClothModifierData *clmd,
MVert *loc0 = col->collmd->x;
MVert *loc1 = col->collmd->xnew;
float vel[3];
float weights[8];
int di, dj, dk;
for (v=0; v < col->collmd->numverts; v++, loc0++, loc1++) {
int offset = hair_grid_offset(loc1->co, hair_grid_res, gmin, gmax);
if (offset < 0 || offset >= size)
int offset = hair_grid_offset(loc1->co, res, gmin, scale);
if (!hair_grid_point_valid(loc1->co, gmin, gmax))
continue;
sub_v3_v3v3(vel, loc1->co, loc0->co);
add_v3_v3(collgrid[offset].velocity, vel);
collgrid[offset].density += 1.0f;
hair_grid_weights(res, gmin, scale, lX[v], offset, weights);
for (di = 0; di < 2; ++di) {
for (dj = 0; dj < 2; ++dj) {
for (dk = 0; dk < 2; ++dk) {
int voffset = offset + di + (dj + dk*res)*res;
int iw = di + dj*2 + dk*4;
collgrid[voffset].density += weights[iw];
madd_v3_v3fl(collgrid[voffset].velocity, vel, weights[iw]);
}
}
}
}
}
}
@@ -1395,12 +1461,9 @@ static HairGridVert *hair_volume_create_collision_grid(ClothModifierData *clmd,
/* divide velocity with density */
for (i = 0; i < size; i++) {
density = collgrid[i].density;
if (density > 0.0f) {
collgrid[i].velocity[0] /= density;
collgrid[i].velocity[1] /= density;
collgrid[i].velocity[2] /= density;
}
float density = collgrid[i].density;
if (density > 0.0f)
mul_v3_fl(collgrid[i].velocity, 1.0f/density);
}
return collgrid;