Fix T90387: division by zero when trying to invert scale

Fix division by zero when `BKE_bone_parent_transform_invert()` inverts a
scale vector with zero components.

Zero values in the to-be-inverted vector are now simply skipped, i.e.
remain zero after inversion. This at least ensures that
`invert_v3_safe(invert_v3_safe(vector))` results in the same vector.

This commit does NOT fix the conceptual problem that an inversion of a
potentially non-invertible vector is relied upon. It just avoids the
division by zero.

1 files changed, 13 insertions, 0 deletions

diff --git a/source/blender/blenlib/intern/math_vector_inline.c b/source/blender/blenlib/intern/math_vector_inline.c
index 55f7a152b83..dddefd60b1b 100644
--- a/source/blender/blenlib/intern/math_vector_inline.c
+++ b/source/blender/blenlib/intern/math_vector_inline.c
@@ -847,6 +847,19 @@ MINLINE void invert_v3(float r[3])
   r[2] = 1.0f / r[2];
 }
 
+MINLINE void invert_v3_safe(float r[3])
+{
+  if (r[0] != 0.0f) {
+    r[0] = 1.0f / r[0];
+  }
+  if (r[1] != 0.0f) {
+    r[1] = 1.0f / r[1];
+  }
+  if (r[2] != 0.0f) {
+    r[2] = 1.0f / r[2];
+  }
+}
+
 MINLINE void abs_v2(float r[2])
 {
   r[0] = fabsf(r[0]);