[Bf-blender-cvs] [9959cce4] hair_immediate_fixes: Transform the constraint matrix and target solver vector z according to the root frame transforms as well.

[Lukas Tönne]

Commit: 9959cce4b6ec6bb698520c33d1143fef0f9a590e
Author: Lukas Tönne
Date:   Fri Sep 12 12:30:13 2014 +0200
Branches: hair_immediate_fixes
https://developer.blender.org/rB9959cce4b6ec6bb698520c33d1143fef0f9a590e

Transform the constraint matrix and target solver vector z according to
the root frame transforms as well.

This ensures the hair constraints are actually in root space and applied
correctly by the solver.

===================================================================

M       source/blender/blenkernel/intern/implicit.c

===================================================================

diff --git a/source/blender/blenkernel/intern/implicit.c 
b/source/blender/blenkernel/intern/implicit.c
index 33b5404..f79e6f2 100644
--- a/source/blender/blenkernel/intern/implicit.c
+++ b/source/blender/blenkernel/intern/implicit.c
@@ -2288,10 +2288,12 @@ bool implicit_hair_volume_get_texture_data(Object 
*UNUSED(ob), ClothModifierData
  * This is part of the modified CG method suggested by Baraff/Witkin in
  * "Large Steps in Cloth Simulation" (Siggraph 1998)
  */
-static void setup_constraint_matrix(ClothModifierData *clmd, ColliderContacts 
*contacts, int totcolliders, lfVector *V, fmatrix3x3 *S, lfVector *z, float dt)
+static void setup_constraint_matrix(ClothModifierData *clmd, ColliderContacts 
*contacts, int totcolliders, lfVector *X, lfVector *V, fmatrix3x3 *S, lfVector 
*z, float dt)
 {
-       ClothVertex *verts = clmd->clothObject->verts;
-       int numverts = clmd->clothObject->numverts;
+       Cloth *cloth = clmd->clothObject;
+       ClothVertex *verts = cloth->verts;
+       int numverts = cloth->numverts;
+       RootTransform *roots = cloth->implicit->root;
        int i, j, v;
 
        for (v = 0; v < numverts; v++) {
@@ -2343,6 +2345,17 @@ static void setup_constraint_matrix(ClothModifierData 
*clmd, ColliderContacts *c
                        }
                }
        }
+       
+       /* transform to root space */
+       for (v = 0; v < numverts; v++) {
+               float t[3][3];
+               copy_m3_m3(t, roots[v].rot);
+               transpose_m3(t);
+               mul_m3_m3m3(S[v].m, S[v].m, t);
+               mul_m3_m3m3(S[v].m, roots[v].rot, S[v].m);
+               
+               vel_world_to_root(z[v], X[v], z[v], &roots[v]);
+       }
 }
 
 static void cloth_calc_force(ClothModifierData *clmd, float UNUSED(frame), 
lfVector *lF, lfVector *lX, lfVector *lV, fmatrix3x3 *dFdV, fmatrix3x3 *dFdX, 
ListBase *effectors, float time, fmatrix3x3 *M)
@@ -2687,7 +2700,7 @@ int implicit_solver(Object *ob, float frame, 
ClothModifierData *clmd, ListBase *
                }
                
                /* setup vertex constraints for pinned vertices and contacts */
-               setup_constraint_matrix(clmd, contacts, totcolliders, id->V, 
id->S, id->z, dt);
+               setup_constraint_matrix(clmd, contacts, totcolliders, id->X, 
id->V, id->S, id->z, dt);
                
                // damping velocity for artistic reasons
                mul_lfvectorS(id->V, id->V, clmd->sim_parms->vel_damping, 
numverts);

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