[Bf-blender-cvs] [aea3097] master: Perform grid-based velocity smoothing for hair outside of the implicit solver step.
Lukas Tönne
noreply at git.blender.org
Tue Jan 20 09:52:06 CET 2015
Commit: aea309779f631e4f0bb6fa2a38f39d4f4db4de97
Author: Lukas Tönne
Date: Fri Oct 31 11:59:14 2014 +0100
Branches: master
https://developer.blender.org/rBaea309779f631e4f0bb6fa2a38f39d4f4db4de97
Perform grid-based velocity smoothing for hair outside of the implicit
solver step.
Calculating forces and jacobians from linearly interpolated grid values
is problematic due to discontinuities at the grid boundaries. The new
approach of modifying velocities after the backward euler solver step
was suggested in a newer paper
"Detail Preserving Continuum Simulation of Straight Hair"
(McAdams, Selle 2009)
Conflicts:
source/blender/physics/intern/BPH_mass_spring.cpp
===================================================================
M source/blender/physics/intern/BPH_mass_spring.cpp
M source/blender/physics/intern/hair_volume.c
M source/blender/physics/intern/implicit.h
M source/blender/physics/intern/implicit_blender.c
M source/blender/physics/intern/implicit_eigen.cpp
===================================================================
diff --git a/source/blender/physics/intern/BPH_mass_spring.cpp b/source/blender/physics/intern/BPH_mass_spring.cpp
index 153993d..821b08c 100644
--- a/source/blender/physics/intern/BPH_mass_spring.cpp
+++ b/source/blender/physics/intern/BPH_mass_spring.cpp
@@ -453,54 +453,6 @@ static void hair_get_boundbox(ClothModifierData *clmd, float gmin[3], float gmax
}
}
-static void cloth_calc_volume_force(ClothModifierData *clmd)
-{
- ClothSimSettings *parms = clmd->sim_parms;
- Cloth *cloth = clmd->clothObject;
- Implicit_Data *data = cloth->implicit;
- int numverts = cloth->numverts;
-
- /* 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);
-
- for (i = 0; i < numverts; i++) {
- float x[3], v[3];
-
- BPH_mass_spring_get_motion_state(data, i, x, v);
- BPH_hair_volume_add_vertex(vertex_grid, x, v);
- }
- BPH_hair_volume_normalize_vertex_grid(vertex_grid);
-
-#if 0
- /* apply velocity filter */
- BPH_hair_volume_vertex_grid_filter_box(vertex_grid, clmd->sim_parms->voxel_filter_size);
-#endif
-
- for (i = 0; i < numverts; i++) {
- float x[3], v[3], f[3], dfdx[3][3], dfdv[3][3];
-
- /* calculate volumetric forces */
- BPH_mass_spring_get_motion_state(data, i, 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, i, f, dfdx, dfdv);
- }
-
- BPH_hair_volume_free_vertex_grid(vertex_grid);
- }
-}
-
static void cloth_calc_force(ClothModifierData *clmd, float UNUSED(frame), ListBase *effectors, float time)
{
/* Collect forces and derivatives: F, dFdX, dFdV */
@@ -525,7 +477,7 @@ static void cloth_calc_force(ClothModifierData *clmd, float UNUSED(frame), ListB
}
#endif
- cloth_calc_volume_force(clmd);
+ /* cloth_calc_volume_force(clmd); */
#ifdef CLOTH_FORCE_DRAG
BPH_mass_spring_force_drag(data, drag);
@@ -570,6 +522,125 @@ static void cloth_calc_force(ClothModifierData *clmd, float UNUSED(frame), ListB
}
}
+#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 numverts = cloth->numverts;
+ 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 < numverts; 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);
+
+#if 0
+ /* apply velocity filter */
+ BPH_hair_volume_vertex_grid_filter_box(vertex_grid, clmd->sim_parms->voxel_filter_size);
+#endif
+
+ vert = cloth->verts;
+ for (i = 0; i < numverts; 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
+
+static void cloth_continuum_step(ClothModifierData *clmd)
+{
+ ClothSimSettings *parms = clmd->sim_parms;
+ Cloth *cloth = clmd->clothObject;
+ Implicit_Data *data = cloth->implicit;
+ int numverts = cloth->numverts;
+ ClothVertex *vert;
+
+ const float fluid_factor = 0.95f; /* blend between PIC and FLIP methods */
+ /* 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 < numverts; i++, vert++) {
+ float x[3], v[3];
+
+ BPH_mass_spring_get_motion_state(data, i, x, v);
+ BPH_hair_volume_add_vertex(vertex_grid, x, v);
+ }
+ BPH_hair_volume_normalize_vertex_grid(vertex_grid);
+
+#if 0
+ /* apply velocity filter */
+ BPH_hair_volume_vertex_grid_filter_box(vertex_grid, clmd->sim_parms->voxel_filter_size);
+#endif
+
+ vert = cloth->verts;
+ for (i = 0; i < numverts; 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(vertex_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);
+ }
+
+ BPH_hair_volume_free_vertex_grid(vertex_grid);
+ }
+}
+
static void cloth_clear_result(ClothModifierData *clmd)
{
ClothSolverResult *sres = clmd->solver_result;
@@ -686,9 +757,13 @@ int BPH_cloth_solve(Object *ob, float frame, ClothModifierData *clmd, ListBase *
cloth_calc_force(clmd, frame, effectors, step);
// calculate new velocity and position
- BPH_mass_spring_solve(id, dt, &result);
+ BPH_mass_spring_solve_velocities(id, dt, &result);
cloth_record_result(clmd, &result, clmd->sim_parms->stepsPerFrame);
+ cloth_continuum_step(clmd);
+
+ BPH_mass_spring_solve_positions(id, dt);
+
BPH_mass_spring_apply_result(id);
/* move pinned verts to correct position */
diff --git a/source/blender/physics/intern/hair_volume.c b/source/blender/physics/intern/hair_volume.c
index e72df49..87f202b 100644
--- a/source/blender/physics/intern/hair_volume.c
+++ b/source/blender/physics/intern/hair_volume.c
@@ -220,6 +220,18 @@ void BPH_hair_volume_vertex_grid_forces(HairVertexGrid *grid, const float x[3],
mul_m3_fl(dfdv, smoothfac);
}
+void BPH_hair_volume_grid_velocity(HairVertexGrid *grid, const float x[3], const float v[3],
+ float fluid_factor,
+ float r_v[3])
+{
+ float gdensity, gvelocity[3], ggrad[3], gvelgrad[3][3];
+
+ hair_grid_interpolate(grid->verts, grid->res, grid->gmin, grid->scale, x, &gdensity, gvelocity, ggrad, gvelgrad);
+
+ /* XXX TODO implement FLIP method and use fluid_factor to blend between FLIP and PIC */
+ copy_v3_v3(r_v, gvelocity);
+}
+
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] ||
diff --git a/source/blender/physics/intern/implicit.h b/source/blender/physics/intern/implicit.h
index 4678b27..012125b 100644
--- a/source/blender/physics/intern/implicit.h
+++ b/source/blender/physics/intern/implicit.h
@@ -111,20 +111,26 @@ BLI_INLINE int hash_collpair(int type, CollPair *collpair)
void BPH_mass_spring_solver_debug_data(struct Implicit_Data *id, struct SimDebugData *debug_data);
+void BPH_mass_spring_set_vertex_mass(struct Implicit_Data *data, int index, float mass);
void BPH_mass_spring_set_rest_transform(struct Implicit_Data *data, int index, float rot[3][3]);
void BPH_mass_spring_set_motion_state(struct Implicit_Data *data, int index, const float x[3], const float v[3]);
void BPH_mass_spring_set_position(struct Implicit_Data *data, int index, const float x[3]);
void BPH_mass_spring_set_velocity(struct Implicit_Data *data, int index, const float v[3]);
void BPH_mass_spring_get_motion_state(struct Implicit_Data *data, int index, float x[3], float v[3]);
-void BPH_mass_spring_set_vertex_mass(struct Implicit_Data *data, int index, float mass);
+void BPH_mass_spring_get_position(struct Implicit_Data *data, int index, float x[3]);
+
+/* modified velocity during solver step */
+void BPH_mass_spring_get_new_velocity(struct Implicit_Data *data, int index, float v[3]);
+void BPH_mass_spring_set_new_velocity(struct Implicit_Data *data, int index, const float v[3]);
void BPH_mass_spring_clear_constraints(struct Implicit_Data *data);
void BPH_mass_spring_add_constraint_ndof0(struct Implicit_Data *data, int index, const float dV[3]);
void BPH_mass_spring_add_constraint_ndof1(struct Implicit_Data *data, int index, const float c1[3], const float c2[3], const float dV[3]);
void BPH_mass_spring_add_constraint_ndof2(struct Implicit_Data *data, int index, const float c1[3], const float dV[3]);
-bool BPH_mass_spring_solve(struct Implicit_Data *data, float dt, struct ImplicitSolverResult *result);
+bool BPH_mass_spring_solve_velocities(struct Implicit_Data *data, float dt, struct ImplicitSolverResult *result);
+bool BPH_mass_spring_solve_positions(struct Implicit_Data *data, float dt);
void BPH_mass_spring_apply_result(struct Implicit_Data *data);
/* Clear the force vector at the beginning of the time step */
@@ -170,6 +176,20 @@ void BPH_hair_volume_normalize_vertex_grid(struct HairVertexGrid *grid);
#if 0 /* XXX weighting is incorrect, disa
@@ Diff output truncated at 10240 characters. @@
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