diff options
| -rw-r--r-- | source/blender/blenkernel/intern/constraint.c | 32 | ||||
| -rw-r--r-- | source/blender/blenlib/BLI_math_vector.h | 1 | ||||
| -rw-r--r-- | source/blender/blenlib/intern/math_vector_inline.c | 10 |
3 files changed, 41 insertions, 2 deletions
diff --git a/source/blender/blenkernel/intern/constraint.c b/source/blender/blenkernel/intern/constraint.c index 2a5a0cf9ae7..7d861658993 100644 --- a/source/blender/blenkernel/intern/constraint.c +++ b/source/blender/blenkernel/intern/constraint.c @@ -3709,7 +3709,7 @@ static void damptrack_evaluate(bConstraint *con, bConstraintOb *cob, ListBase *t * - the min/max wrappers around (obvec . tarvec) result (stored temporarily in rangle) * are used to ensure that the smallest angle is chosen */ - cross_v3_v3v3(raxis, obvec, tarvec); + cross_v3_v3v3_hi_prec(raxis, obvec, tarvec); rangle = dot_v3v3(obvec, tarvec); rangle = acosf(max_ff(-1.0f, min_ff(1.0f, rangle))); @@ -3717,7 +3717,35 @@ static void damptrack_evaluate(bConstraint *con, bConstraintOb *cob, ListBase *t /* construct rotation matrix from the axis-angle rotation found above * - this call takes care to make sure that the axis provided is a unit vector first */ - axis_angle_to_mat3(rmat, raxis, rangle); + float norm = normalize_v3(raxis); + + if (norm < FLT_EPSILON) { + /* if dot product is nonzero, while cross is zero, we have two opposite vectors! + * - this is an ambiguity in the math that needs to be resolved arbitrarily, + * or there will be a case where damped track strangely does nothing + * - to do that, rotate around a different local axis + */ + float tmpvec[3]; + + if (fabsf(rangle) < M_PI - 0.01f) { + return; + } + + rangle = M_PI; + copy_v3_v3(tmpvec, track_dir_vecs[(data->trackflag + 1) % 6]); + mul_mat3_m4_v3(cob->matrix, tmpvec); + cross_v3_v3v3(raxis, obvec, tmpvec); + + if (normalize_v3(raxis) == 0.0f) { + return; + } + } + else if (norm < 0.1f) { + /* near 0 and Pi arcsin has way better precision than arccos */ + rangle = (rangle > M_PI_2) ? M_PI - asinf(norm) : asinf(norm); + } + + axis_angle_normalized_to_mat3(rmat, raxis, rangle); /* rotate the owner in the way defined by this rotation matrix, then reapply the location since * we may have destroyed that in the process of multiplying the matrix 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 |