Fix for particle instance initial frames.

These were not orthonormal and tended to flip with changing hair
direction, now use the particle hair matrix which is stable wrt. the
mesh surface.

1 files changed, 5 insertions, 10 deletions

diff --git a/source/blender/modifiers/intern/MOD_particleinstance.c b/source/blender/modifiers/intern/MOD_particleinstance.c
index e58ec24f43b..fbb2e16a6a7 100644
--- a/source/blender/modifiers/intern/MOD_particleinstance.c
+++ b/source/blender/modifiers/intern/MOD_particleinstance.c
@@ -43,6 +43,7 @@
 #include "BLI_utildefines.h"
 
 #include "BKE_cdderivedmesh.h"
+#include "BKE_effect.h"
 #include "BKE_global.h"
 #include "BKE_lattice.h"
 #include "BKE_modifier.h"
@@ -327,17 +328,11 @@ static DerivedMesh *applyModifier(ModifierData *md, Object *ob,
 
 				/* Incrementally Rotating Frame (Bishop Frame) */
 				if (k == 0) {
+					float hairmat[4][4];
 					float mat[3][3];
-					float temp[3] = {0.0f, 0.0f, 0.0f};
-					temp[axis] = 1.0f;
 					
-					/* normal direction */
-					copy_v3_v3(mat[0], state.vel);
-					/* tangent from projecting axis onto the surface plane */
-					project_v3_plane(mat[1], state.vel, temp);
-					normalize_v3(mat[1]);
-					/* cotangent */
-					cross_v3_v3v3(mat[2], mat[0], mat[1]);
+					psys_mat_hair_to_global(sim.ob, sim.psmd->dm, sim.psys->part->from, pa, hairmat);
+					copy_m3_m4(mat, hairmat);
 					/* to quaternion */
 					mat3_to_quat(frame, mat);
 					
@@ -355,7 +350,7 @@ static DerivedMesh *applyModifier(ModifierData *md, Object *ob,
 					mul_qt_qtqt(frame, rot, frame);
 					
 					copy_v3_v3(prev_dir, state.vel);
-					}
+				}
 				
 				copy_qt_qt(state.rot, frame);
 #if 0