diff options
| author | Alexander Gavrilov <angavrilov@gmail.com> | 2018-07-07 23:21:20 +0300 |
|---|---|---|
| committer | Alexander Gavrilov <angavrilov@gmail.com> | 2018-07-19 17:58:27 +0300 |
| commit | 0bf8096501a8e7883f4061ba3e425966ba7517cd (patch) | |
| tree | 0535d2a4df15dc45c02b114bdd34f615f3a0d61a /source/blender/blenlib | |
| parent | 51f14cfa43e5fe4bdea6fbd5c668a44919657f99 (diff) | |
Resolve the opposite vector ambiguity in Damped Track constraint.
Damped Track by specification attempts to arrive at the desired
direction via the shortest rotation. However with opposite vectors
there are infinitely many valid 180 degree rotations. Currently
it gives up and does nothing.
I think that it would be more reasonable to resolve the ambiguity
arbitrarily, so that Damped Track won't have a weird dead zone.
To make it more predictable I use a local axis.
In addition, the singularity area vicinity has some floating
point precision problems that result in significant jitter.
This applies workarounds for two causes of instability.
Differential Revision: https://developer.blender.org/D3530
Diffstat (limited to 'source/blender/blenlib')
| -rw-r--r-- | source/blender/blenlib/BLI_math_vector.h | 1 | ||||
| -rw-r--r-- | source/blender/blenlib/intern/math_vector_inline.c | 10 |
2 files changed, 11 insertions, 0 deletions
diff --git a/source/blender/blenlib/BLI_math_vector.h b/source/blender/blenlib/BLI_math_vector.h index 3f603311530..39625346756 100644 --- a/source/blender/blenlib/BLI_math_vector.h +++ b/source/blender/blenlib/BLI_math_vector.h @@ -169,6 +169,7 @@ MINLINE double dot_v3db_v3fl(const double a[3], const float b[3]) ATTR_WARN_UNUS MINLINE float cross_v2v2(const float a[2], const float b[2]) ATTR_WARN_UNUSED_RESULT; MINLINE void cross_v3_v3v3(float r[3], const float a[3], const float b[3]); +MINLINE void cross_v3_v3v3_hi_prec(float r[3], const float a[3], const float b[3]); MINLINE void add_newell_cross_v3_v3v3(float n[3], const float v_prev[3], const float v_curr[3]); diff --git a/source/blender/blenlib/intern/math_vector_inline.c b/source/blender/blenlib/intern/math_vector_inline.c index 08687a1ab47..715e2e65c96 100644 --- a/source/blender/blenlib/intern/math_vector_inline.c +++ b/source/blender/blenlib/intern/math_vector_inline.c @@ -753,6 +753,16 @@ MINLINE void cross_v3_v3v3(float r[3], const float a[3], const float b[3]) r[2] = a[0] * b[1] - a[1] * b[0]; } +/* cross product suffers from severe precision loss when vectors are + * nearly parallel or opposite; doing the computation in double helps a lot */ +MINLINE void cross_v3_v3v3_hi_prec(float r[3], const float a[3], const float b[3]) +{ + BLI_assert(r != a && r != b); + r[0] = (float)((double)a[1] * (double)b[2] - (double)a[2] * (double)b[1]); + r[1] = (float)((double)a[2] * (double)b[0] - (double)a[0] * (double)b[2]); + r[2] = (float)((double)a[0] * (double)b[1] - (double)a[1] * (double)b[0]); +} + /* Newell's Method */ /* excuse this fairly specific function, * its used for polygon normals all over the place |