Commit: bd033721c248a906a9734fa872ea7d075039aba9
Author: Lukas Tönne
Date: Mon Nov 17 14:16:35 2014 +0100
Branches: master
https://developer.blender.org/rBbd033721c248a906a9734fa872ea7d075039aba9
Fix for particle instance modifier: use a stable parallel-transport
framing method instead of the Frenet frame.
The Frenet frame is very succeptible to sudden twists along straight
sections of a curve where the second derivative (curvature) becomes 0.
===================================================================
M source/blender/modifiers/intern/MOD_particleinstance.c
===================================================================
diff --git a/source/blender/modifiers/intern/MOD_particleinstance.c
b/source/blender/modifiers/intern/MOD_particleinstance.c
index 768bed1..e58ec24 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_global.h"
#include "BKE_lattice.h"
#include "BKE_modifier.h"
#include "BKE_particle.h"
@@ -276,6 +277,9 @@ static DerivedMesh *applyModifier(ModifierData *md, Object
*ob,
orig_mloop = dm->getLoopArray(dm);
for (p = 0, p_skip = 0; p < totpart; p++) {
+ float prev_dir[3];
+ float frame[4]; /* frame orientation quaternion */
+
/* skip particle? */
if (particle_skip(pimd, psys, p))
continue;
@@ -321,19 +325,54 @@ static DerivedMesh *applyModifier(ModifierData *md,
Object *ob,
normalize_v3(state.vel);
- /* TODO: incremental rotations somehow */
+ /* Incrementally Rotating Frame (Bishop Frame)
*/
+ if (k == 0) {
+ 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]);
+ /* to quaternion */
+ mat3_to_quat(frame, mat);
+
+ /* note: direction is same as normal
vector currently,
+ * but best to keep this separate so
the frame can be
+ * rotated later if necessary
+ */
+ copy_v3_v3(prev_dir, state.vel);
+ }
+ else {
+ float rot[4];
+
+ /* incrementally rotate along bend
direction */
+ rotation_between_vecs_to_quat(rot,
prev_dir, state.vel);
+ mul_qt_qtqt(frame, rot, frame);
+
+ copy_v3_v3(prev_dir, state.vel);
+ }
+
+ copy_qt_qt(state.rot, frame);
+#if 0
+ /* Absolute Frame (Frenet Frame) */
if (state.vel[axis] < -0.9999f ||
state.vel[axis] > 0.9999f) {
unit_qt(state.rot);
}
else {
float temp[3] = {0.0f, 0.0f, 0.0f};
temp[axis] = 1.0f;
-
+
cross_v3_v3v3(cross, temp, state.vel);
-
+
/* state.vel[axis] is the only
component surviving from a dot product with the axis */
axis_angle_to_quat(state.rot, cross,
saacos(state.vel[axis]));
}
+#endif
}
else {
state.time = -1.0;
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