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Correctly implemented and verified gravity, drag, structural springs.

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This commit is contained in:
Lukas Tönne 2014-09-10 18:55:15 +02:00
parent f336ca5952
commit 6d4c704f17
2 changed files with 62 additions and 42 deletions
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2
source/blender/blenkernel/intern/implicit.h
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@ -41,7 +41,7 @@
#define CLOTH_FORCE_DRAG #define CLOTH_FORCE_DRAG
#define CLOTH_FORCE_SPRING_STRUCTURAL #define CLOTH_FORCE_SPRING_STRUCTURAL
#define CLOTH_FORCE_SPRING_BEND #define CLOTH_FORCE_SPRING_BEND
#define CLOTH_FORCE_SPRING_GOAL //#define CLOTH_FORCE_SPRING_GOAL
#define IMPLICIT_PRINT_SOLVER_INPUT_OUTPUT #define IMPLICIT_PRINT_SOLVER_INPUT_OUTPUT

90
source/blender/blenkernel/intern/implicit_eigen.cpp
View File

@ -175,42 +175,21 @@ BLI_INLINE void lMatrix_copy_m3(lMatrix &r, float m[3][3], int i, int j)
BLI_INLINE void lMatrix_add_m3(lMatrix &r, float m[3][3], int i, int j) BLI_INLINE void lMatrix_add_m3(lMatrix &r, float m[3][3], int i, int j)
{ {
lMatrix tmp(r.cols(), r.cols()); lMatrix tmp(r.cols(), r.cols());
if (i == j) {
lMatrix_copy_m3(tmp, m, i, i);
}
else {
lMatrix_copy_m3(tmp, m, i, j); lMatrix_copy_m3(tmp, m, i, j);
lMatrix_copy_m3(tmp, m, j, i);
}
r += tmp; r += tmp;
} }
BLI_INLINE void lMatrix_sub_m3(lMatrix &r, float m[3][3], int i, int j) BLI_INLINE void lMatrix_sub_m3(lMatrix &r, float m[3][3], int i, int j)
{ {
lMatrix tmp(r.cols(), r.cols()); lMatrix tmp(r.cols(), r.cols());
if (i == j) {
lMatrix_copy_m3(tmp, m, i, i);
}
else {
lMatrix_copy_m3(tmp, m, i, j); lMatrix_copy_m3(tmp, m, i, j);
lMatrix_copy_m3(tmp, m, j, i);
}
r -= tmp; r -= tmp;
} }
BLI_INLINE void lMatrix_madd_m3(lMatrix &r, float m[3][3], float s, int i, int j) BLI_INLINE void lMatrix_madd_m3(lMatrix &r, float m[3][3], float s, int i, int j)
{ {
lMatrix tmp(r.cols(), r.cols()); lMatrix tmp(r.cols(), r.cols());
if (i == j) {
lMatrix_copy_m3(tmp, m, i, i);
}
else {
lMatrix_copy_m3(tmp, m, i, j); lMatrix_copy_m3(tmp, m, i, j);
lMatrix_copy_m3(tmp, m, j, i);
}
r += s * tmp; r += s * tmp;
} }
@ -341,7 +320,7 @@ BLI_INLINE void dfdx_spring(float to[3][3], const float dir[3], float length, fl
mul_m3_fl(to, (L/length)); mul_m3_fl(to, (L/length));
sub_m3_m3m3(to, to, I); sub_m3_m3m3(to, to, I);
mul_m3_fl(to, -k); mul_m3_fl(to, k);
} }
/* unused */ /* unused */
@ -356,16 +335,54 @@ BLI_INLINE void dfdx_damp(float to[3][3], const float dir[3], float length, cons
} }
#endif #endif
DO_INLINE void dfdv_damp(float to[3][3], const float dir[3], float damping) BLI_INLINE void dfdv_damp(float to[3][3], const float dir[3], float damping)
{ {
// derivative of force wrt velocity // derivative of force wrt velocity
outerproduct(to, dir, dir); outerproduct(to, dir, dir);
mul_m3_fl(to, damping); mul_m3_fl(to, -damping);
}
BLI_INLINE float fb(float length, float L)
{
float x = length / L;
return (-11.541f * powf(x, 4) + 34.193f * powf(x, 3) - 39.083f * powf(x, 2) + 23.116f * x - 9.713f);
}
BLI_INLINE float fbderiv(float length, float L)
{
float x = length/L;
return (-46.164f * powf(x, 3) + 102.579f * powf(x, 2) - 78.166f * x + 23.116f);
}
BLI_INLINE float fbstar(float length, float L, float kb, float cb)
{
float tempfb_fl = kb * fb(length, L);
float fbstar_fl = cb * (length - L);
if (tempfb_fl < fbstar_fl)
return fbstar_fl;
else
return tempfb_fl;
}
// function to calculae bending spring force (taken from Choi & Co)
BLI_INLINE float fbstar_jacobi(float length, float L, float kb, float cb)
{
float tempfb_fl = kb * fb(length, L);
float fbstar_fl = cb * (length - L);
if (tempfb_fl < fbstar_fl) {
return cb;
}
else {
return kb * fbderiv(length, L);
}
} }
static void cloth_calc_spring_force(ClothModifierData *clmd, ClothSpring *s, const lVector &X, const lVector &V, float time) static void cloth_calc_spring_force(ClothModifierData *clmd, ClothSpring *s, const lVector &X, const lVector &V, float time)
{ {
const float structural_scale = 0.001f; const float structural_scale = 1.0f;
Cloth *cloth = clmd->clothObject; Cloth *cloth = clmd->clothObject;
ClothVertex *verts = cloth->verts; ClothVertex *verts = cloth->verts;
@ -378,10 +395,6 @@ static void cloth_calc_spring_force(ClothModifierData *clmd, ClothSpring *s, con
float L = s->restlen; float L = s->restlen;
float cb; /* = clmd->sim_parms->structural; */ /*UNUSED*/ float cb; /* = clmd->sim_parms->structural; */ /*UNUSED*/
float stretch_force[3] = {0, 0, 0};
float bending_force[3] = {0, 0, 0};
float nulldfdx[3][3] = {{0, 0, 0}, {0, 0, 0}, {0, 0, 0}};
float scaling = 0.0; float scaling = 0.0;
int no_compress = clmd->sim_parms->flags & CLOTH_SIMSETTINGS_FLAG_NO_SPRING_COMPRESS; int no_compress = clmd->sim_parms->flags & CLOTH_SIMSETTINGS_FLAG_NO_SPRING_COMPRESS;
@ -392,8 +405,8 @@ static void cloth_calc_spring_force(ClothModifierData *clmd, ClothSpring *s, con
s->flags &= ~CLOTH_SPRING_FLAG_NEEDED; s->flags &= ~CLOTH_SPRING_FLAG_NEEDED;
/* ignore springs between pinned vertices */ /* ignore springs between pinned vertices */
if (v1->flags & CLOTH_VERT_FLAG_PINNED && v2->flags & CLOTH_VERT_FLAG_PINNED) // if (v1->flags & CLOTH_VERT_FLAG_PINNED && v2->flags & CLOTH_VERT_FLAG_PINNED)
return; // return;
// calculate elonglation // calculate elonglation
sub_v3_v3v3(extent, lVector_v3(X, s->kl), lVector_v3(X, s->ij)); sub_v3_v3v3(extent, lVector_v3(X, s->kl), lVector_v3(X, s->ij));
@ -422,6 +435,8 @@ static void cloth_calc_spring_force(ClothModifierData *clmd, ClothSpring *s, con
if (ELEM(s->type, CLOTH_SPRING_TYPE_STRUCTURAL, CLOTH_SPRING_TYPE_SHEAR, CLOTH_SPRING_TYPE_SEWING)) { if (ELEM(s->type, CLOTH_SPRING_TYPE_STRUCTURAL, CLOTH_SPRING_TYPE_SHEAR, CLOTH_SPRING_TYPE_SEWING)) {
#ifdef CLOTH_FORCE_SPRING_STRUCTURAL #ifdef CLOTH_FORCE_SPRING_STRUCTURAL
if (length > L || no_compress) { if (length > L || no_compress) {
float stretch_force[3] = {0, 0, 0};
s->flags |= CLOTH_SPRING_FLAG_NEEDED; s->flags |= CLOTH_SPRING_FLAG_NEEDED;
k = clmd->sim_parms->structural * structural_scale; k = clmd->sim_parms->structural * structural_scale;
@ -496,10 +511,10 @@ static void cloth_calc_spring_force(ClothModifierData *clmd, ClothSpring *s, con
scaling = k + s->stiffness * fabsf(clmd->sim_parms->max_bend - k); scaling = k + s->stiffness * fabsf(clmd->sim_parms->max_bend - k);
cb = k = scaling / (20.0f * (clmd->sim_parms->avg_spring_len + FLT_EPSILON)); cb = k = scaling / (20.0f * (clmd->sim_parms->avg_spring_len + FLT_EPSILON));
mul_fvector_S(bending_force, dir, fbstar(length, L, k, cb)); madd_v3_v3fl(s->f, dir, -fbstar(length, L, k, cb));
VECADD(s->f, s->f, bending_force);
dfdx_spring_type2(s->dfdx, dir, length, L, k, cb); outerproduct(s->dfdx, dir, dir);
mul_m3_fl(s->dfdx, -fbstar_jacobi(length, L, k, cb));
} }
#endif #endif
} }
@ -515,16 +530,21 @@ static void cloth_apply_spring_force(ClothModifierData *clmd, ClothSpring *s, lV
return; return;
if (!(s->type & CLOTH_SPRING_TYPE_BENDING)) { if (!(s->type & CLOTH_SPRING_TYPE_BENDING)) {
lMatrix_add_m3(dFdV, s->dfdv, s->ij, s->ij);
lMatrix_add_m3(dFdV, s->dfdv, s->kl, s->kl);
lMatrix_sub_m3(dFdV, s->dfdv, s->ij, s->kl); lMatrix_sub_m3(dFdV, s->dfdv, s->ij, s->kl);
lMatrix_sub_m3(dFdV, s->dfdv, s->kl, s->ij);
} }
add_v3_v3(lVector_v3(F, s->ij), s->f); add_v3_v3(lVector_v3(F, s->ij), s->f);
if (!(s->type & CLOTH_SPRING_TYPE_GOAL)) { if (!(s->type & CLOTH_SPRING_TYPE_GOAL)) {
sub_v3_v3(lVector_v3(F, s->kl), s->f); sub_v3_v3(lVector_v3(F, s->kl), s->f);
} }
lMatrix_add_m3(dFdX, s->dfdx, s->ij, s->ij);
lMatrix_add_m3(dFdX, s->dfdx, s->kl, s->kl);
lMatrix_sub_m3(dFdX, s->dfdx, s->ij, s->kl); lMatrix_sub_m3(dFdX, s->dfdx, s->ij, s->kl);
lMatrix_sub_m3(dFdX, s->dfdx, s->kl, s->ij);
} }
static void cloth_calc_force(ClothModifierData *clmd, lVector &F, lMatrix &dFdX, lMatrix &dFdV, const lVector &X, const lVector &V, const lMatrix &M, ListBase *effectors, float time) static void cloth_calc_force(ClothModifierData *clmd, lVector &F, lMatrix &dFdX, lMatrix &dFdV, const lVector &X, const lVector &V, const lMatrix &M, ListBase *effectors, float time)