Commit: 6d4c704f17596b05b50dbb8e34bdd25159f4ff2f
Author: Lukas Tönne
Date: Wed Sep 10 18:55:15 2014 +0200
Branches: master
https://developer.blender.org/rB6d4c704f17596b05b50dbb8e34bdd25159f4ff2f
Correctly implemented and verified gravity, drag, structural springs.
===================================================================
M source/blender/blenkernel/intern/implicit.h
M source/blender/blenkernel/intern/implicit_eigen.cpp
===================================================================
diff --git a/source/blender/blenkernel/intern/implicit.h
b/source/blender/blenkernel/intern/implicit.h
index 4124e52..9335b4c 100644
--- a/source/blender/blenkernel/intern/implicit.h
+++ b/source/blender/blenkernel/intern/implicit.h
@@ -41,7 +41,7 @@
#define CLOTH_FORCE_DRAG
#define CLOTH_FORCE_SPRING_STRUCTURAL
#define CLOTH_FORCE_SPRING_BEND
-#define CLOTH_FORCE_SPRING_GOAL
+//#define CLOTH_FORCE_SPRING_GOAL
#define IMPLICIT_PRINT_SOLVER_INPUT_OUTPUT
diff --git a/source/blender/blenkernel/intern/implicit_eigen.cpp
b/source/blender/blenkernel/intern/implicit_eigen.cpp
index 4f44df9..2cf9815 100644
--- a/source/blender/blenkernel/intern/implicit_eigen.cpp
+++ b/source/blender/blenkernel/intern/implicit_eigen.cpp
@@ -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)
{
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, j, i);
- }
-
+ lMatrix_copy_m3(tmp, m, i, j);
r += tmp;
}
BLI_INLINE void lMatrix_sub_m3(lMatrix &r, float m[3][3], int i, int j)
{
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, j, i);
- }
-
+ lMatrix_copy_m3(tmp, m, i, j);
r -= tmp;
}
BLI_INLINE void lMatrix_madd_m3(lMatrix &r, float m[3][3], float s, int i, int
j)
{
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, j, i);
- }
-
+ lMatrix_copy_m3(tmp, m, i, j);
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));
sub_m3_m3m3(to, to, I);
- mul_m3_fl(to, -k);
+ mul_m3_fl(to, k);
}
/* unused */
@@ -356,16 +335,54 @@ BLI_INLINE void dfdx_damp(float to[3][3], const float
dir[3], float length, cons
}
#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
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)
{
- const float structural_scale = 0.001f;
+ const float structural_scale = 1.0f;
Cloth *cloth = clmd->clothObject;
ClothVertex *verts = cloth->verts;
@@ -378,10 +395,6 @@ static void cloth_calc_spring_force(ClothModifierData
*clmd, ClothSpring *s, con
float L = s->restlen;
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;
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;
/* ignore springs between pinned vertices */
- if (v1->flags & CLOTH_VERT_FLAG_PINNED && v2->flags &
CLOTH_VERT_FLAG_PINNED)
- return;
+// if (v1->flags & CLOTH_VERT_FLAG_PINNED && v2->flags &
CLOTH_VERT_FLAG_PINNED)
+// return;
// calculate elonglation
sub_v3_v3v3(extent, lVector_v3(X, s->kl), lVector_v3(X, s->ij));
@@ -422,11 +435,13 @@ 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)) {
#ifdef CLOTH_FORCE_SPRING_STRUCTURAL
if (length > L || no_compress) {
+ float stretch_force[3] = {0, 0, 0};
+
s->flags |= CLOTH_SPRING_FLAG_NEEDED;
k = clmd->sim_parms->structural * structural_scale;
scaling = k + s->stiffness *
fabsf(clmd->sim_parms->max_struct - k);
-
+
k = scaling / (clmd->sim_parms->avg_spring_len +
FLT_EPSILON);
// TODO: verify, half verified (couldn't see error)
if (s->type & CLOTH_SPRING_TYPE_SEWING) {
@@ -495,11 +510,11 @@ static void cloth_calc_spring_force(ClothModifierData
*clmd, ClothSpring *s, con
scaling = k + s->stiffness *
fabsf(clmd->sim_parms->max_bend - k);
cb = k = scaling / (20.0f *
(clmd->sim_parms->avg_spring_len + FLT_EPSILON));
-
- mul_fvector_S(bending_force, dir, fbstar(length, L, k,
cb));
- VECADD(s->f, s->f, bending_force);
-
- dfdx_spring_type2(s->dfdx, dir, length, L, k, cb);
+
+ madd_v3_v3fl(s->f, dir, -fbstar(length, L, k, cb));
+
+ outerproduct(s->dfdx, dir, dir);
+ mul_m3_fl(s->dfdx, -fbstar_jacobi(length, L, k, cb));
}
#endif
}
@@ -515,16 +530,21 @@ static void cloth_apply_spring_force(ClothModifierData
*clmd, ClothSpring *s, lV
return;
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->kl, s->ij);
}
add_v3_v3(lVector_v3(F, s->ij), s->f);
if (!(s->type & CLOTH_SPRING_TYPE_GOAL)) {
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->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)
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