diff options
author | Campbell Barton <campbell@blender.org> | 2022-11-09 02:18:05 +0300 |
---|---|---|
committer | Campbell Barton <campbell@blender.org> | 2022-11-09 04:23:01 +0300 |
commit | 494385a5bcc4c08832b50ca57e21cf85981fe922 (patch) | |
tree | d389337dca64df7a261bf5f1cd4c1d15a4d55429 | |
parent | ee5b6f7150109a62b2a435ecd011316ffceb9e59 (diff) |
Fix T101848: Zeroed matrix converted to a quaternion results in rotation
Re-order checks to ensure a zeroed matrix results in a quaternion
without rotation. Also avoid some redundant calculation where the
'trace' was calculated but not used, flip the scaling value early
on instead of negating the quaternion after calculating it.
-rw-r--r-- | source/blender/blenlib/intern/math_rotation.c | 83 | ||||
-rw-r--r-- | source/blender/blenlib/tests/BLI_math_rotation_test.cc | 16 |
2 files changed, 59 insertions, 40 deletions
diff --git a/source/blender/blenlib/intern/math_rotation.c b/source/blender/blenlib/intern/math_rotation.c index ff45bbee5c9..17e43b545d8 100644 --- a/source/blender/blenlib/intern/math_rotation.c +++ b/source/blender/blenlib/intern/math_rotation.c @@ -275,63 +275,66 @@ void mat3_normalized_to_quat_fast(float q[4], const float mat[3][3]) /* Caller must ensure matrices aren't negative for valid results, see: T24291, T94231. */ BLI_assert(!is_negative_m3(mat)); - /* Check the trace of the matrix - bad precision if close to -1. */ - const float trace = mat[0][0] + mat[1][1] + mat[2][2]; - - if (trace > 0) { - float s = 2.0f * sqrtf(1.0f + trace); - - q[0] = 0.25f * s; - - s = 1.0f / s; - - q[1] = (mat[1][2] - mat[2][1]) * s; - q[2] = (mat[2][0] - mat[0][2]) * s; - q[3] = (mat[0][1] - mat[1][0]) * s; - } - else { - /* Find the biggest diagonal element to choose the best formula. - * Here trace should also be always >= 0, avoiding bad precision. */ - if (mat[0][0] > mat[1][1] && mat[0][0] > mat[2][2]) { - float s = 2.0f * sqrtf(1.0f + mat[0][0] - mat[1][1] - mat[2][2]); - + /* Method outlined by Mike Day, ref: https://math.stackexchange.com/a/3183435/220949 + * with an additional `sqrtf(..)` for higher precision result. + * Removing the `sqrt` causes tests to fail unless the precision is set to 1e-6 or larger. */ + + if (mat[2][2] < 0.0f) { + if (mat[0][0] > mat[1][1]) { + const float trace = 1.0f + mat[0][0] - mat[1][1] - mat[2][2]; + float s = 2.0f * sqrtf(trace); + if (mat[1][2] < mat[2][1]) { + /* Ensure W is non-negative for a canonical result. */ + s = -s; + } q[1] = 0.25f * s; - s = 1.0f / s; - q[0] = (mat[1][2] - mat[2][1]) * s; - q[2] = (mat[1][0] + mat[0][1]) * s; + q[2] = (mat[0][1] + mat[1][0]) * s; q[3] = (mat[2][0] + mat[0][2]) * s; } - else if (mat[1][1] > mat[2][2]) { - float s = 2.0f * sqrtf(1.0f + mat[1][1] - mat[0][0] - mat[2][2]); - + else { + const float trace = 1.0f - mat[0][0] + mat[1][1] - mat[2][2]; + float s = 2.0f * sqrtf(trace); + if (mat[2][0] < mat[0][2]) { + /* Ensure W is non-negative for a canonical result. */ + s = -s; + } q[2] = 0.25f * s; - s = 1.0f / s; - q[0] = (mat[2][0] - mat[0][2]) * s; - q[1] = (mat[1][0] + mat[0][1]) * s; - q[3] = (mat[2][1] + mat[1][2]) * s; + q[1] = (mat[0][1] + mat[1][0]) * s; + q[3] = (mat[1][2] + mat[2][1]) * s; } - else { - float s = 2.0f * sqrtf(1.0f + mat[2][2] - mat[0][0] - mat[1][1]); - + } + else { + if (mat[0][0] < -mat[1][1]) { + const float trace = 1.0f - mat[0][0] - mat[1][1] + mat[2][2]; + float s = 2.0f * sqrtf(trace); + if (mat[0][1] < mat[1][0]) { + /* Ensure W is non-negative for a canonical result. */ + s = -s; + } q[3] = 0.25f * s; - s = 1.0f / s; - q[0] = (mat[0][1] - mat[1][0]) * s; q[1] = (mat[2][0] + mat[0][2]) * s; - q[2] = (mat[2][1] + mat[1][2]) * s; + q[2] = (mat[1][2] + mat[2][1]) * s; } - - /* Make sure W is non-negative for a canonical result. */ - if (q[0] < 0) { - negate_v4(q); + else { + /* NOTE(@campbellbarton): A zero matrix will fall through to this block, + * needed so a zero scaled matrices to return a quaternion without rotation, see: T101848. */ + const float trace = 1.0f + mat[0][0] + mat[1][1] + mat[2][2]; + float s = 2.0f * sqrtf(trace); + q[0] = 0.25f * s; + s = 1.0f / s; + q[1] = (mat[1][2] - mat[2][1]) * s; + q[2] = (mat[2][0] - mat[0][2]) * s; + q[3] = (mat[0][1] - mat[1][0]) * s; } } + BLI_assert(!(q[0] < 0.0f)); normalize_qt(q); } diff --git a/source/blender/blenlib/tests/BLI_math_rotation_test.cc b/source/blender/blenlib/tests/BLI_math_rotation_test.cc index e37b212e1df..0c8ae38c386 100644 --- a/source/blender/blenlib/tests/BLI_math_rotation_test.cc +++ b/source/blender/blenlib/tests/BLI_math_rotation_test.cc @@ -3,6 +3,7 @@ #include "testing/testing.h" #include "BLI_math_base.h" +#include "BLI_math_matrix.h" #include "BLI_math_rotation.h" #include "BLI_math_rotation.hh" #include "BLI_math_vector.hh" @@ -138,6 +139,21 @@ TEST(math_rotation, quat_to_mat_to_quat_near_0001) test_quat_to_mat_to_quat(0.30f, -0.030f, -0.30f, 0.95f); } +/* A zeroed matrix converted to a quaternion and back should not add rotation, see: T101848 */ +TEST(math_rotation, quat_to_mat_to_quat_zeroed_matrix) +{ + float matrix_zeroed[3][3] = {{0.0f}}; + float matrix_result[3][3]; + float matrix_unit[3][3]; + float out_quat[4]; + + unit_m3(matrix_unit); + mat3_normalized_to_quat(out_quat, matrix_zeroed); + quat_to_mat3(matrix_result, out_quat); + + EXPECT_M3_NEAR(matrix_unit, matrix_result, FLT_EPSILON); +} + TEST(math_rotation, quat_split_swing_and_twist_negative) { const float input[4] = {-0.5f, 0, sqrtf(3) / 2, 0}; |