Partial fix for T38871, Bevel could create a far-out spike.

There needed to be a check that when a newly created point is
supposed to be on an edge, that it stays within the bounds
of either end of the edge.
This fixes the hole-in-cube example in the bug, but not
the boolean modifier one, which still needs more work.

1 files changed, 23 insertions, 0 deletions

diff --git a/source/blender/bmesh/tools/bmesh_bevel.c b/source/blender/bmesh/tools/bmesh_bevel.c
index ba289bb4de4..dcb604056fa 100644
--- a/source/blender/bmesh/tools/bmesh_bevel.c
+++ b/source/blender/bmesh/tools/bmesh_bevel.c
@@ -552,6 +552,15 @@ static void slide_dist(EdgeHalf *e, BMVert *v, float d, float slideco[3])
 	madd_v3_v3fl(slideco, dir, -d);
 }
 
+/* Is co not on the edge e? */
+static bool is_outside_edge(EdgeHalf *e, const float co[3])
+{
+	float d_squared;
+
+	d_squared = dist_squared_to_line_segment_v3(co, e->e->v1->co, e->e->v2->co);
+	return d_squared > BEVEL_EPSILON_SQ;
+}
+
 /*
  * Calculate the meeting point between the offset edges for e1 and e2, putting answer in meetco.
  * e1 and e2 share vertex v and face f (may be NULL) and viewed from the normal side of
@@ -633,6 +642,20 @@ static void offset_meet(EdgeHalf *e1, EdgeHalf *e2, BMVert *v, BMFace *f, float
 			if (fabsf(d - e2->offset_l) > BEVEL_EPSILON)
 				e2->offset_l = d;
 		}
+		else {
+			/* The lines intersect, but is it at a reasonable place?
+			 * One problem to check: if one of the offsets is 0, then don't
+			 * want an intersection that is outside that edge itself.
+			 * This can happen if angle between them is > 180 degrees. */
+			if (e1->offset_r == 0.0f && is_outside_edge(e1, meetco)) {
+				copy_v3_v3(meetco, v->co);
+				e2->offset_l = 0.0f;
+			}
+			if (e2->offset_l == 0.0f && is_outside_edge(e2, meetco)) {
+				copy_v3_v3(meetco, v->co);
+				e1->offset_r = 0.0f;
+			}
+		}
 	}
 }