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-rw-r--r--libdimension/geometry.c6
1 files changed, 5 insertions, 1 deletions
diff --git a/libdimension/geometry.c b/libdimension/geometry.c
index 26ca628..6b1019b 100644
--- a/libdimension/geometry.c
+++ b/libdimension/geometry.c
@@ -87,8 +87,12 @@ dmnsn_vector_axis_angle(dmnsn_vector v1, dmnsn_vector v2, dmnsn_vector axis)
dmnsn_vector d = dmnsn_vector_sub(v1, v2);
dmnsn_vector proj = dmnsn_vector_add(dmnsn_vector_proj(d, axis), v2);
+ double projn = dmnsn_vector_norm(proj);
+ if (!projn)
+ return 0.0;
+
double c = dmnsn_vector_dot(dmnsn_vector_normalize(v1),
- dmnsn_vector_normalize(proj));
+ dmnsn_vector_div(proj, projn));
double angle = acos(c);
if (dmnsn_vector_dot(dmnsn_vector_cross(v1, proj), axis) > 0) {