Fix T39184: Multisegment bevel profiles should curve in-plane sometimes.

When the multisegment profile joins two unbeveled edges, all in the same
plane, users desire that rather than the current behavior of linear
interpolation between those edges, the profile should curve.
This changes behavior to do that.  The old behavior can be obtained
by setting the profile parameter to 0.25, if desired.

1 files changed, 32 insertions, 13 deletions

diff --git a/source/blender/bmesh/tools/bmesh_bevel.c b/source/blender/bmesh/tools/bmesh_bevel.c
index 2ef93618e2a..86b46c900ec 100644
--- a/source/blender/bmesh/tools/bmesh_bevel.c
+++ b/source/blender/bmesh/tools/bmesh_bevel.c
@@ -909,7 +909,7 @@ static void project_to_edge(BMEdge *e, const float co_a[3], const float co_b[3],
 /* If there is a bndv->ebev edge, find the mid control point if necessary.
  * It is the closest point on the beveled edge to the line segment between
  * bndv and bndv->next.  */
-static void set_profile_params(BevelParams *bp, BoundVert *bndv)
+static void set_profile_params(BevelParams *bp, BevVert *bv, BoundVert *bndv)
 {
 	EdgeHalf *e;
 	Profile *pro;
@@ -947,18 +947,37 @@ static void set_profile_params(BevelParams *bp, BoundVert *bndv)
 		cross_v3_v3v3(pro->plane_no, d1, d2);
 		l = normalize_v3(pro->plane_no);
 		if (l  <= BEVEL_EPSILON_BIG) {
-			/* co1 - midco -co2 are collinear - project plane that contains that line
-			 * and is perpendicular to the plane containing it and the beveled edge */
-			cross_v3_v3v3(d3, d1, pro->proj_dir);
-			normalize_v3(d3);
-			cross_v3_v3v3(pro->plane_no, d1, d3);
-			l = normalize_v3(pro->plane_no);
-			if (l <= BEVEL_EPSILON_BIG) {
-				/* whole profile is collinear with edge: just interpolate */
+			/* co1 - midco -co2 are collinear.
+			 * Should be case that beveled edge is coplanar with two boundary verts.
+			 * If the profile is going to lead into unbeveled edges on each side
+			 * (that is, both BoundVerts are "on-edge" points on non-beveled edges)
+			 * then in order to get curve in multi-segment case, change projection plane
+			 * to be that common plane, projection dir to be the plane normal,
+			 * and mid to be the original vertex.
+			 * Otherwise, we just want to linearly interpolate between co1 and co2.
+			 */
+			if (e->prev->is_bev || e->next->is_bev) {
 				do_linear_interp = true;
 			}
-			/* signal to weld that this is linear */
-			pro->super_r = PRO_LINE_R;
+			else {
+				copy_v3_v3(pro->coa, co1);
+				copy_v3_v3(pro->midco, bv->v->co);
+				copy_v3_v3(pro->cob, co2);
+				sub_v3_v3v3(d1, pro->midco, co1);
+				normalize_v3(d1);
+				sub_v3_v3v3(d2, pro->midco, co2);
+				normalize_v3(d2);
+				cross_v3_v3v3(pro->plane_no, d1, d2);
+				l = normalize_v3(pro->plane_no);
+				if (l <= BEVEL_EPSILON_BIG) {
+					/* whole profile is collinear with edge: just interpolate */
+					do_linear_interp = true;
+				}
+				else {
+					copy_v3_v3(pro->plane_co, bv->v->co);
+					copy_v3_v3(pro->proj_dir, pro->plane_no);
+				}
+			}
 		}
 		copy_v3_v3(pro->plane_co, co1);
 	}
@@ -1474,7 +1493,7 @@ static void build_boundary(BevelParams *bp, BevVert *bv, bool construct)
 		else {
 			adjust_bound_vert(e->next->leftv, co);
 		}
-		set_profile_params(bp, vm->boundstart);
+		set_profile_params(bp, bv, vm->boundstart);
 		calculate_profile(bp, vm->boundstart);
 		return;
 	}
@@ -1580,7 +1599,7 @@ static void build_boundary(BevelParams *bp, BevVert *bv, bool construct)
 
 	v = vm->boundstart;
 	do {
-		set_profile_params(bp, v);
+		set_profile_params(bp, bv, v);
 		calculate_profile(bp, v);
 	} while ((v = v->next) != vm->boundstart);