Fix T100796: wrong tangents on bezier splines with duplicate points and handles

Differential Revision: https://developer.blender.org/D15880

1 files changed, 5 insertions, 2 deletions

diff --git a/source/blender/blenkernel/intern/curves_geometry.cc b/source/blender/blenkernel/intern/curves_geometry.cc
index af9533dc77f..940ec407d04 100644
--- a/source/blender/blenkernel/intern/curves_geometry.cc
+++ b/source/blender/blenkernel/intern/curves_geometry.cc
@@ -733,11 +733,14 @@ Span<float3> CurvesGeometry::evaluated_tangents() const
           const IndexRange points = this->points_for_curve(curve_index);
           const IndexRange evaluated_points = this->evaluated_points_for_curve(curve_index);
 
-          if (handles_right[points.first()] != positions[points.first()]) {
+          const float epsilon = 1e-6f;
+          if (!math::almost_equal_relative(
+                  handles_right[points.first()], positions[points.first()], epsilon)) {
             tangents[evaluated_points.first()] = math::normalize(handles_right[points.first()] -
                                                                  positions[points.first()]);
           }
-          if (handles_left[points.last()] != positions[points.last()]) {
+          if (!math::almost_equal_relative(
+                  handles_left[points.last()], positions[points.last()], epsilon)) {
             tangents[evaluated_points.last()] = math::normalize(positions[points.last()] -
                                                                 handles_left[points.last()]);
           }