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path: root/source/blender/physics/intern/implicit_blender.c
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-rw-r--r--source/blender/physics/intern/implicit_blender.c189
1 files changed, 160 insertions, 29 deletions
diff --git a/source/blender/physics/intern/implicit_blender.c b/source/blender/physics/intern/implicit_blender.c
index e4d93b72f73..b98518fedc0 100644
--- a/source/blender/physics/intern/implicit_blender.c
+++ b/source/blender/physics/intern/implicit_blender.c
@@ -461,6 +461,13 @@ DO_INLINE void muladd_fmatrix_fvector(float to[3], float matrix[3][3], float fro
to[2] += dot_v3v3(matrix[2], from);
}
+DO_INLINE void muladd_fmatrixT_fvector(float to[3], float matrix[3][3], float from[3])
+{
+ to[0] += matrix[0][0] * from[0] + matrix[1][0] * from[1] + matrix[2][0] * from[2];
+ to[1] += matrix[0][1] * from[0] + matrix[1][1] * from[1] + matrix[2][1] * from[2];
+ to[2] += matrix[0][2] * from[0] + matrix[1][2] * from[1] + matrix[2][2] * from[2];
+}
+
BLI_INLINE void outerproduct(float r[3][3], const float a[3], const float b[3])
{
mul_v3_v3fl(r[0], a, b[0]);
@@ -604,7 +611,9 @@ DO_INLINE void mul_bfmatrix_lfvector( float (*to)[3], fmatrix3x3 *from, lfVector
#pragma omp section
{
for (i = from[0].vcount; i < from[0].vcount+from[0].scount; i++) {
- muladd_fmatrix_fvector(to[from[i].c], from[i].m, fLongVector[from[i].r]);
+ /* This is the lower triangle of the sparse matrix,
+ * therefore multiplication occurs with transposed submatrices. */
+ muladd_fmatrixT_fvector(to[from[i].c], from[i].m, fLongVector[from[i].r]);
}
}
#pragma omp section
@@ -617,8 +626,6 @@ DO_INLINE void mul_bfmatrix_lfvector( float (*to)[3], fmatrix3x3 *from, lfVector
add_lfvector_lfvector(to, to, temp, from[0].vcount);
del_lfvector(temp);
-
-
}
/* SPARSE SYMMETRIC sub big matrix with big matrix*/
@@ -1585,9 +1592,13 @@ BLI_INLINE void apply_spring(Implicit_Data *data, int i, int j, const float f[3]
}
bool BPH_mass_spring_force_spring_linear(Implicit_Data *data, int i, int j, float restlen,
- float stiffness, float damping, bool no_compress, float clamp_force)
+ float stiffness_tension, float damping_tension,
+ float stiffness_compression, float damping_compression,
+ bool resist_compress, bool new_compress, float clamp_force)
{
float extent[3], length, dir[3], vel[3];
+ float f[3], dfdx[3][3], dfdv[3][3];
+ float damping = 0;
// calculate elonglation
spring_length(data, i, j, extent, dir, &length, vel);
@@ -1595,29 +1606,41 @@ bool BPH_mass_spring_force_spring_linear(Implicit_Data *data, int i, int j, floa
/* This code computes not only the force, but also its derivative.
Zero derivative effectively disables the spring for the implicit solver.
Thus length > restlen makes cloth unconstrained at the start of simulation. */
- if ((length >= restlen && length > 0) || no_compress) {
- float stretch_force, f[3], dfdx[3][3], dfdv[3][3];
+ if ((length >= restlen && length > 0) || resist_compress) {
+ float stretch_force;
+
+ damping = damping_tension;
- stretch_force = stiffness * (length - restlen);
+ stretch_force = stiffness_tension * (length - restlen);
if (clamp_force > 0.0f && stretch_force > clamp_force) {
stretch_force = clamp_force;
}
mul_v3_v3fl(f, dir, stretch_force);
- // Ascher & Boxman, p.21: Damping only during elonglation
- // something wrong with it...
- madd_v3_v3fl(f, dir, damping * dot_v3v3(vel, dir));
+ dfdx_spring(dfdx, dir, length, restlen, stiffness_tension);
+ }
+ else if (new_compress) {
+ /* This is based on the Choi and Ko bending model, which works surprisingly well for compression. */
+ float kb = stiffness_compression;
+ float cb = kb; /* cb equal to kb seems to work, but a factor can be added if necessary */
- dfdx_spring(dfdx, dir, length, restlen, stiffness);
- dfdv_damp(dfdv, dir, damping);
+ damping = damping_compression;
- apply_spring(data, i, j, f, dfdx, dfdv);
+ mul_v3_v3fl(f, dir, fbstar(length, restlen, kb, cb));
- return true;
+ outerproduct(dfdx, dir, dir);
+ mul_m3_fl(dfdx, fbstar_jacobi(length, restlen, kb, cb));
}
else {
return false;
}
+
+ madd_v3_v3fl(f, dir, damping * dot_v3v3(vel, dir));
+ dfdv_damp(dfdv, dir, damping);
+
+ apply_spring(data, i, j, f, dfdx, dfdv);
+
+ return true;
}
/* See "Stable but Responsive Cloth" (Choi, Ko 2005) */
@@ -1648,6 +1671,114 @@ bool BPH_mass_spring_force_spring_bending(Implicit_Data *data, int i, int j, flo
}
}
+BLI_INLINE void poly_avg(lfVector *data, int *inds, int len, float r_avg[3])
+{
+ float fact = 1.0f / (float)len;
+
+ zero_v3(r_avg);
+
+ for (int i = 0; i < len; i++) {
+ madd_v3_v3fl(r_avg, data[inds[i]], fact);
+ }
+}
+
+BLI_INLINE void poly_norm(lfVector *data, int i, int j, int *inds, int len, float r_dir[3])
+{
+ float mid[3];
+
+ poly_avg(data, inds, len, mid);
+
+ normal_tri_v3(r_dir, data[i], data[j], mid);
+}
+
+BLI_INLINE void edge_avg(lfVector *data, int i, int j, float r_avg[3])
+{
+ r_avg[0] = (data[i][0] + data[j][0]) * 0.5f;
+ r_avg[1] = (data[i][1] + data[j][1]) * 0.5f;
+ r_avg[2] = (data[i][2] + data[j][2]) * 0.5f;
+}
+
+BLI_INLINE void edge_norm(lfVector *data, int i, int j, float r_dir[3])
+{
+ sub_v3_v3v3(r_dir, data[i], data[j]);
+ normalize_v3(r_dir);
+}
+
+BLI_INLINE float bend_angle(float dir_a[3], float dir_b[3], float dir_e[3])
+{
+ float cos, sin;
+ float tmp[3];
+
+ cos = dot_v3v3(dir_a, dir_b);
+
+ cross_v3_v3v3(tmp, dir_a, dir_b);
+ sin = dot_v3v3(tmp, dir_e);
+
+ return atan2f(sin, cos);
+}
+
+BLI_INLINE void spring_angle(Implicit_Data *data, int i, int j, int *i_a, int *i_b, int len_a, int len_b,
+ float r_dir_a[3], float r_dir_b[3],
+ float *r_angle, float r_vel_a[3], float r_vel_b[3])
+{
+ float dir_e[3], vel_e[3];
+
+ poly_norm(data->X, j, i, i_a, len_a, r_dir_a);
+ poly_norm(data->X, i, j, i_b, len_b, r_dir_b);
+
+ edge_norm(data->X, i, j, dir_e);
+
+ *r_angle = bend_angle(r_dir_a, r_dir_b, dir_e);
+
+ poly_avg(data->V, i_a, len_a, r_vel_a);
+ poly_avg(data->V, i_b, len_b, r_vel_b);
+
+ edge_avg(data->V, i, j, vel_e);
+
+ sub_v3_v3(r_vel_a, vel_e);
+ sub_v3_v3(r_vel_b, vel_e);
+}
+
+/* Angular springs roughly based on the bending model proposed by Baraff and Witkin in "Large Steps in Cloth Simulation". */
+bool BPH_mass_spring_force_spring_angular(Implicit_Data *data, int i, int j, int *i_a, int *i_b, int len_a, int len_b,
+ float restang, float stiffness, float damping)
+{
+ float angle, dir_a[3], dir_b[3], vel_a[3], vel_b[3];
+ float f_a[3], f_b[3], f_e[3];
+ float force;
+ int x;
+
+ spring_angle(data, i, j, i_a, i_b, len_a, len_b,
+ dir_a, dir_b, &angle, vel_a, vel_b);
+
+ /* spring force */
+ force = stiffness * (angle - restang);
+
+ /* damping force */
+ force += -damping * (dot_v3v3(vel_a, dir_a) + dot_v3v3(vel_b, dir_b));
+
+ mul_v3_v3fl(f_a, dir_a, force / len_a);
+ mul_v3_v3fl(f_b, dir_b, force / len_b);
+
+ for (x = 0; x < len_a; x++) {
+ add_v3_v3(data->F[i_a[x]], f_a);
+ }
+
+ for (x = 0; x < len_b; x++) {
+ add_v3_v3(data->F[i_b[x]], f_b);
+ }
+
+ mul_v3_v3fl(f_a, dir_a, force * 0.5f);
+ mul_v3_v3fl(f_b, dir_b, force * 0.5f);
+
+ add_v3_v3v3(f_e, f_a, f_b);
+
+ sub_v3_v3(data->F[i], f_e);
+ sub_v3_v3(data->F[j], f_e);
+
+ return true;
+}
+
/* Jacobian of a direction vector.
* Basically the part of the differential orthogonal to the direction,
* inversely proportional to the length of the edge.
@@ -1671,7 +1802,7 @@ BLI_INLINE void spring_grad_dir(Implicit_Data *data, int i, int j, float edge[3]
}
}
-BLI_INLINE void spring_angbend_forces(Implicit_Data *data, int i, int j, int k,
+BLI_INLINE void spring_hairbend_forces(Implicit_Data *data, int i, int j, int k,
const float goal[3],
float stiffness, float damping,
int q, const float dx[3], const float dv[3],
@@ -1720,7 +1851,7 @@ BLI_INLINE void spring_angbend_forces(Implicit_Data *data, int i, int j, int k,
}
/* Finite Differences method for estimating the jacobian of the force */
-BLI_INLINE void spring_angbend_estimate_dfdx(Implicit_Data *data, int i, int j, int k,
+BLI_INLINE void spring_hairbend_estimate_dfdx(Implicit_Data *data, int i, int j, int k,
const float goal[3],
float stiffness, float damping,
int q, float dfdx[3][3])
@@ -1739,11 +1870,11 @@ BLI_INLINE void spring_angbend_estimate_dfdx(Implicit_Data *data, int i, int j,
/* XXX TODO offset targets to account for position dependency */
for (a = 0; a < 3; ++a) {
- spring_angbend_forces(data, i, j, k, goal, stiffness, damping,
+ spring_hairbend_forces(data, i, j, k, goal, stiffness, damping,
q, dvec_pos[a], dvec_null[a], f);
copy_v3_v3(dfdx[a], f);
- spring_angbend_forces(data, i, j, k, goal, stiffness, damping,
+ spring_hairbend_forces(data, i, j, k, goal, stiffness, damping,
q, dvec_neg[a], dvec_null[a], f);
sub_v3_v3(dfdx[a], f);
@@ -1754,7 +1885,7 @@ BLI_INLINE void spring_angbend_estimate_dfdx(Implicit_Data *data, int i, int j,
}
/* Finite Differences method for estimating the jacobian of the force */
-BLI_INLINE void spring_angbend_estimate_dfdv(Implicit_Data *data, int i, int j, int k,
+BLI_INLINE void spring_hairbend_estimate_dfdv(Implicit_Data *data, int i, int j, int k,
const float goal[3],
float stiffness, float damping,
int q, float dfdv[3][3])
@@ -1773,11 +1904,11 @@ BLI_INLINE void spring_angbend_estimate_dfdv(Implicit_Data *data, int i, int j,
/* XXX TODO offset targets to account for position dependency */
for (a = 0; a < 3; ++a) {
- spring_angbend_forces(data, i, j, k, goal, stiffness, damping,
+ spring_hairbend_forces(data, i, j, k, goal, stiffness, damping,
q, dvec_null[a], dvec_pos[a], f);
copy_v3_v3(dfdv[a], f);
- spring_angbend_forces(data, i, j, k, goal, stiffness, damping,
+ spring_hairbend_forces(data, i, j, k, goal, stiffness, damping,
q, dvec_null[a], dvec_neg[a], f);
sub_v3_v3(dfdv[a], f);
@@ -1790,7 +1921,7 @@ BLI_INLINE void spring_angbend_estimate_dfdv(Implicit_Data *data, int i, int j,
/* Angular spring that pulls the vertex toward the local target
* See "Artistic Simulation of Curly Hair" (Pixar technical memo #12-03a)
*/
-bool BPH_mass_spring_force_spring_bending_angular(Implicit_Data *data, int i, int j, int k,
+bool BPH_mass_spring_force_spring_bending_hair(Implicit_Data *data, int i, int j, int k,
const float target[3], float stiffness, float damping)
{
float goal[3];
@@ -1806,18 +1937,18 @@ bool BPH_mass_spring_force_spring_bending_angular(Implicit_Data *data, int i, in
world_to_root_v3(data, j, goal, target);
- spring_angbend_forces(data, i, j, k, goal, stiffness, damping, k, vecnull, vecnull, fk);
+ spring_hairbend_forces(data, i, j, k, goal, stiffness, damping, k, vecnull, vecnull, fk);
negate_v3_v3(fj, fk); /* counterforce */
- spring_angbend_estimate_dfdx(data, i, j, k, goal, stiffness, damping, i, dfk_dxi);
- spring_angbend_estimate_dfdx(data, i, j, k, goal, stiffness, damping, j, dfk_dxj);
- spring_angbend_estimate_dfdx(data, i, j, k, goal, stiffness, damping, k, dfk_dxk);
+ spring_hairbend_estimate_dfdx(data, i, j, k, goal, stiffness, damping, i, dfk_dxi);
+ spring_hairbend_estimate_dfdx(data, i, j, k, goal, stiffness, damping, j, dfk_dxj);
+ spring_hairbend_estimate_dfdx(data, i, j, k, goal, stiffness, damping, k, dfk_dxk);
copy_m3_m3(dfj_dxi, dfk_dxi); negate_m3(dfj_dxi);
copy_m3_m3(dfj_dxj, dfk_dxj); negate_m3(dfj_dxj);
- spring_angbend_estimate_dfdv(data, i, j, k, goal, stiffness, damping, i, dfk_dvi);
- spring_angbend_estimate_dfdv(data, i, j, k, goal, stiffness, damping, j, dfk_dvj);
- spring_angbend_estimate_dfdv(data, i, j, k, goal, stiffness, damping, k, dfk_dvk);
+ spring_hairbend_estimate_dfdv(data, i, j, k, goal, stiffness, damping, i, dfk_dvi);
+ spring_hairbend_estimate_dfdv(data, i, j, k, goal, stiffness, damping, j, dfk_dvj);
+ spring_hairbend_estimate_dfdv(data, i, j, k, goal, stiffness, damping, k, dfk_dvk);
copy_m3_m3(dfj_dvi, dfk_dvi); negate_m3(dfj_dvi);
copy_m3_m3(dfj_dvj, dfk_dvj); negate_m3(dfj_dvj);
generated by cgit v1.2.3 (git 2.25.1) at 2024-07-27 13:40:30 +0300