Commit: 72e812de7c0f9a7221b2b7d180edf02fbbde3530
Author: Campbell Barton
Date: Tue Jun 23 20:37:53 2015 +1000
Branches: master
https://developer.blender.org/rB72e812de7c0f9a7221b2b7d180edf02fbbde3530
Fix T45123: 2D line intersection fails
Co-linear lines could detect as intersecting even if they weren't overlapping.
===================================================================
M source/blender/blenlib/intern/math_geom.c
===================================================================
diff --git a/source/blender/blenlib/intern/math_geom.c
b/source/blender/blenlib/intern/math_geom.c
index 8754ad1..2c7c838 100644
--- a/source/blender/blenlib/intern/math_geom.c
+++ b/source/blender/blenlib/intern/math_geom.c
@@ -719,8 +719,26 @@ int isect_seg_seg_v2_point(const float v0[2], const float
v1[2], const float v2[
(v >= -eps && v <= 1.0f + eps))
{
/* intersection */
- madd_v2_v2v2fl(r_vi, v0, s10, u);
- return 1;
+ float vi_test[2];
+ float s_vi_v2[2];
+
+ madd_v2_v2v2fl(vi_test, v0, s10, u);
+
+ /* When 'd' approaches zero, float precision lets
non-overlapping co-linear segments
+ * detect as an intersection. So re-calculate 'v' to
ensure the point overlaps both.
+ * see T45123 */
+
+ /* inline since we have most vars already */
+#if 0
+ v = line_point_factor_v2(ix_test, v2, v3);
+#else
+ sub_v2_v2v2(s_vi_v2, vi_test, v2);
+ v = (dot_v2v2(s32, s_vi_v2) / dot_v2v2(s32, s32));
+#endif
+ if (v >= -eps && v <= 1.0f + eps) {
+ copy_v2_v2(r_vi, vi_test);
+ return 1;
+ }
}
/* out of segment intersection */
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