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First stage of implementing moving frames of reference for hair/cloth.

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This adds transformations for each hair from world to "root space".
Currently positions and velocities are simply transformed for the solver
data and inverse-transformed when copying the results back to the cloth
data. This way the hair movement becomes independent from the movement
of the emitter object. Eventually the "fictitious" forces originating
from emitter movement can be added back in a controlled way.

http://en.wikipedia.org/wiki/Fictitious_force

Ignoring these fictitious forces or scaling their effect is physically
correct, because in the absence of external forces the hair will always
return to rest position in this root frame.

External forces currently are not yet transformed into the root space.
This commit is contained in:
Lukas Tönne 2014-09-11 17:53:25 +02:00
parent d496b308db
commit 55a5351a03
2 changed files with 86 additions and 13 deletions
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84
source/blender/blenkernel/intern/implicit_eigen.cpp
View File

@ -260,7 +260,17 @@ BLI_INLINE void outerproduct(float r[3][3], const float a[3], const float b[3])
mul_v3_v3fl(r[2], a, b[2]);
}
struct RootTransform {
float loc[3];
float rot[3][3];
float vel[3];
float omega[3];
};
struct Implicit_Data {
typedef std::vector<RootTransform> RootTransforms;
Implicit_Data(int numverts)
{
resize(numverts);
@ -275,6 +285,8 @@ struct Implicit_Data {
dFdV.resize(tot, tot);
dFdX.resize(tot, tot);
root.resize(numverts);
X.resize(tot);
Xnew.resize(tot);
V.resize(tot);
@ -296,6 +308,8 @@ struct Implicit_Data {
lVector F; /* forces */
lMatrix dFdV, dFdX; /* force jacobians */
RootTransforms root; /* root transforms */
/* motion state data */
lVector X, Xnew; /* positions */
lVector V, Vnew; /* velocities */
@ -309,6 +323,44 @@ struct Implicit_Data {
lMatrix S; /* filtering matrix for constraints */
};
BLI_INLINE void loc_world_to_root(float r[3], const float v[3], Implicit_Data *id, int i)
{
RootTransform &root = id->root[i];
sub_v3_v3v3(r, v, root.loc);
mul_transposed_m3_v3(root.rot, r);
}
BLI_INLINE void loc_root_to_world(float r[3], const float v[3], Implicit_Data *id, int i)
{
RootTransform &root = id->root[i];
float t[3];
copy_v3_v3(r, v);
mul_m3_v3(root.rot, r);
add_v3_v3(r, root.loc);
}
BLI_INLINE void vel_world_to_root(float r[3], const float x_root[3], const float v[3], Implicit_Data *id, int i)
{
RootTransform &root = id->root[i];
float angvel[3];
cross_v3_v3v3(angvel, root.omega, x_root);
sub_v3_v3v3(r, v, root.vel);
mul_transposed_m3_v3(root.rot, r);
add_v3_v3(r, angvel);
}
BLI_INLINE void vel_root_to_world(float r[3], const float x_root[3], const float v[3], Implicit_Data *id, int i)
{
RootTransform &root = id->root[i];
float angvel[3];
cross_v3_v3v3(angvel, root.omega, x_root);
sub_v3_v3v3(r, v, angvel);
mul_m3_v3(root.rot, r);
add_v3_v3(r, root.vel);
}
static bool simulate_implicit_euler(Implicit_Data *id, float dt)
{
#ifdef USE_EIGEN_CORE
@ -819,8 +871,11 @@ int implicit_solver(Object *ob, float frame, ClothModifierData *clmd, ListBase *
for (int i = 0; i < numverts; i++) {
// update velocities with constrained velocities from pinned verts
if (verts[i].flags & CLOTH_VERT_FLAG_PINNED) {
sub_v3_v3v3(lVector_v3(id->V, i), verts[i].xconst, verts[i].xold);
float v[3];
sub_v3_v3v3(v, verts[i].xconst, verts[i].xold);
// mul_v3_fl(id->V[i], clmd->sim_parms->stepsPerFrame);
/* note: should be zero for root vertices, but other verts could be pinned as well */
vel_world_to_root(lVector_v3(id->V, i), lVector_v3(id->X, i), v, id, i);
}
}
}
@ -835,7 +890,7 @@ int implicit_solver(Object *ob, float frame, ClothModifierData *clmd, ListBase *
/* copy velocities for collision */
for (int i = 0; i < numverts; i++) {
copy_v3_v3(verts[i].tv, lVector_v3(id->V, i));
vel_root_to_world(verts[i].tv, lVector_v3(id->X, i), lVector_v3(id->V, i), id, i);
copy_v3_v3(verts[i].v, verts[i].tv);
}
@ -864,11 +919,14 @@ int implicit_solver(Object *ob, float frame, ClothModifierData *clmd, ListBase *
for (int i = 0; i < numverts; i++) {
/* move pinned verts to correct position */
if (clmd->sim_parms->flags & CLOTH_SIMSETTINGS_FLAG_GOAL) {
if (verts[i].flags & CLOTH_VERT_FLAG_PINNED)
interp_v3_v3v3(lVector_v3(id->Xnew, i), verts[i].xold, verts[i].xconst, step + dt);
if (verts[i].flags & CLOTH_VERT_FLAG_PINNED) {
float x[3];
interp_v3_v3v3(x, verts[i].xold, verts[i].xconst, step + dt);
loc_world_to_root(lVector_v3(id->Xnew, i), x, id, i);
}
}
copy_v3_v3(verts[i].txold, lVector_v3(id->X, i));
loc_root_to_world(verts[i].txold, lVector_v3(id->X, i), id, i);
if (!(verts[i].flags & CLOTH_VERT_FLAG_PINNED) && i > 0) {
BKE_sim_debug_data_add_line(clmd->debug_data, lVector_v3(id->X, i), lVector_v3(id->X, i-1), 0.6, 0.3, 0.3, "hair", hash_vertex(4892, i));
@ -894,13 +952,13 @@ int implicit_solver(Object *ob, float frame, ClothModifierData *clmd, ListBase *
copy_v3_v3(verts[i].x, verts[i].xconst);
copy_v3_v3(verts[i].txold, verts[i].x);
copy_v3_v3(verts[i].v, lVector_v3(id->V, i));
vel_root_to_world(verts[i].v, lVector_v3(id->X, i), lVector_v3(id->V, i), id, i);
}
else {
copy_v3_v3(verts[i].x, lVector_v3(id->X, i));
loc_root_to_world(verts[i].x, lVector_v3(id->X, i), id, i);
copy_v3_v3(verts[i].txold, verts[i].x);
copy_v3_v3(verts[i].v, lVector_v3(id->V, i));
vel_root_to_world(verts[i].v, lVector_v3(id->X, i), lVector_v3(id->V, i), id, i);
}
}
@ -910,15 +968,21 @@ int implicit_solver(Object *ob, float frame, ClothModifierData *clmd, ListBase *
void implicit_set_positions(ClothModifierData *clmd)
{
Cloth *cloth = clmd->clothObject;
Implicit_Data *id = cloth->implicit;
ClothVertex *verts = cloth->verts;
ClothHairRoot *cloth_roots = clmd->roots;
unsigned int numverts = cloth->numverts, i;
Implicit_Data::RootTransforms &root = cloth->implicit->root;
lVector &X = cloth->implicit->X;
lVector &V = cloth->implicit->V;
for (i = 0; i < numverts; i++) {
copy_v3_v3(lVector_v3(X, i), verts[i].x);
copy_v3_v3(lVector_v3(V, i), verts[i].v);
copy_v3_v3(root[i].loc, cloth_roots[i].loc);
copy_m3_m3(root[i].rot, cloth_roots[i].rot);
loc_world_to_root(lVector_v3(X, i), verts[i].x, id, i);
vel_world_to_root(lVector_v3(V, i), lVector_v3(X, i), verts[i].v, id, i);
}
}

15
source/blender/blenkernel/intern/particle_system.c
View File

@ -4033,17 +4033,25 @@ static void do_hair_dynamics(ParticleSimulationData *sim)
/* make vgroup for pin roots etc.. */
psys->particles->hair_index = 1;
LOOP_PARTICLES {
float root_mat[4][4];
if (p)
pa->hair_index = (pa-1)->hair_index + (pa-1)->totkey + 1;
psys_mat_hair_to_object(sim->ob, sim->psmd->dm, psys->part->from, pa, hairmat);
mul_m4_m4m4(root_mat, sim->ob->obmat, hairmat);
for (k=0, key=pa->hair; k<pa->totkey; k++,key++) {
ClothHairRoot *root = &psys->clmd->roots[pa->hair_index + k - 1];
ClothHairRoot *root;
/* create fake root before actual root to resist bending */
if (k==0) {
float temp[3];
root = &psys->clmd->roots[pa->hair_index - 1];
copy_v3_v3(root->loc, root_mat[3]);
copy_m3_m4(root->rot, root_mat);
sub_v3_v3v3(temp, key->co, (key+1)->co);
copy_v3_v3(mvert->co, key->co);
add_v3_v3v3(mvert->co, mvert->co, temp);
@ -4066,8 +4074,9 @@ static void do_hair_dynamics(ParticleSimulationData *sim)
}
/* store root transform in cloth data */
copy_v3_v3(root->loc, hairmat[3]);
copy_m3_m4(root->rot, hairmat);
root = &psys->clmd->roots[pa->hair_index + k];
copy_v3_v3(root->loc, root_mat[3]);
copy_m3_m4(root->rot, root_mat);
copy_v3_v3(mvert->co, key->co);
mul_m4_v3(hairmat, mvert->co);