fix issue with new bridge tool interpolation [#35636]

3 files changed, 32 insertions, 12 deletions

diff --git a/source/blender/bmesh/intern/bmesh_edgeloop.c b/source/blender/bmesh/intern/bmesh_edgeloop.c
index 91812fb2cff..dc3a223ae5d 100644
--- a/source/blender/bmesh/intern/bmesh_edgeloop.c
+++ b/source/blender/bmesh/intern/bmesh_edgeloop.c
@@ -47,7 +47,7 @@ typedef struct BMEdgeLoopStore {
 } BMEdgeLoopStore;
 
 #define BM_EDGELOOP_IS_CLOSED (1 << 0)
-
+#define EDGELOOP_EPS 0.00001f
 
 /* -------------------------------------------------------------------- */
 /* BM_mesh_edgeloops_find & Util Functions  */
@@ -580,7 +580,7 @@ void BM_edgeloop_calc_center(BMesh *UNUSED(bm), BMEdgeLoopStore *el_store)
 
 }
 
-void BM_edgeloop_calc_normal(BMesh *UNUSED(bm), BMEdgeLoopStore *el_store)
+bool BM_edgeloop_calc_normal(BMesh *UNUSED(bm), BMEdgeLoopStore *el_store)
 {
 	LinkData *node_curr = el_store->verts.first;
 	float const *v_prev = NODE_AS_CO(el_store->verts.last);
@@ -601,8 +601,13 @@ void BM_edgeloop_calc_normal(BMesh *UNUSED(bm), BMEdgeLoopStore *el_store)
 		}
 	} while (true);
 
-	if (UNLIKELY(normalize_v3(el_store->no) == 0.0f)) {
+	if (UNLIKELY(normalize_v3(el_store->no) < EDGELOOP_EPS)) {
 		el_store->no[2] = 1.0f; /* other axis set to 0.0 */
+		return false;
+
+	}
+	else {
+		return true;
 	}
 }
 
@@ -612,7 +617,7 @@ void BM_edgeloop_calc_normal(BMesh *UNUSED(bm), BMEdgeLoopStore *el_store)
  *
  * Instead use an alignment vector and calculate the normal based on that.
  */
-void BM_edgeloop_calc_normal_aligned(BMesh *UNUSED(bm), BMEdgeLoopStore *el_store, const float no_align[3])
+bool BM_edgeloop_calc_normal_aligned(BMesh *UNUSED(bm), BMEdgeLoopStore *el_store, const float no_align[3])
 {
 	LinkData *node_curr = el_store->verts.first;
 	float const *v_prev = NODE_AS_CO(el_store->verts.last);
@@ -637,8 +642,12 @@ void BM_edgeloop_calc_normal_aligned(BMesh *UNUSED(bm), BMEdgeLoopStore *el_stor
 		}
 	} while (true);
 
-	if (UNLIKELY(normalize_v3(el_store->no) == 0.0f)) {
+	if (UNLIKELY(normalize_v3(el_store->no) < EDGELOOP_EPS)) {
 		el_store->no[2] = 1.0f; /* other axis set to 0.0 */
+		return false;
+	}
+	else {
+		return true;
 	}
 }
 
diff --git a/source/blender/bmesh/intern/bmesh_edgeloop.h b/source/blender/bmesh/intern/bmesh_edgeloop.h
index 70c30ec73bd..b46509d4030 100644
--- a/source/blender/bmesh/intern/bmesh_edgeloop.h
+++ b/source/blender/bmesh/intern/bmesh_edgeloop.h
@@ -58,8 +58,8 @@ const float        *BM_edgeloop_normal_get(struct BMEdgeLoopStore *el_store);
 const float        *BM_edgeloop_center_get(struct BMEdgeLoopStore *el_store);
 void                BM_edgeloop_edges_get(struct BMEdgeLoopStore *el_store, BMEdge **e_arr);
 void                BM_edgeloop_calc_center(BMesh *bm, struct BMEdgeLoopStore *el_store);
-void                BM_edgeloop_calc_normal(BMesh *bm, struct BMEdgeLoopStore *el_store);
-void                BM_edgeloop_calc_normal_aligned(BMesh *bm, struct BMEdgeLoopStore *el_store,
+bool                BM_edgeloop_calc_normal(BMesh *bm, struct BMEdgeLoopStore *el_store);
+bool                BM_edgeloop_calc_normal_aligned(BMesh *bm, struct BMEdgeLoopStore *el_store,
                                                     const float no_align[3]);
 void                BM_edgeloop_flip(BMesh *bm, struct BMEdgeLoopStore *el_store);
 void                BM_edgeloop_expand(BMesh *bm, struct BMEdgeLoopStore *el_store, int el_store_len);
diff --git a/source/blender/bmesh/operators/bmo_subdivide_edgering.c b/source/blender/bmesh/operators/bmo_subdivide_edgering.c
index 7f08ad2461a..d9555c409f6 100644
--- a/source/blender/bmesh/operators/bmo_subdivide_edgering.c
+++ b/source/blender/bmesh/operators/bmo_subdivide_edgering.c
@@ -547,6 +547,7 @@ static void bm_edgering_pair_interpolate(BMesh *bm, LoopPairStore *lpair,
 {
 	const int resolu = cuts + 2;
 	const int dims = 3;
+	bool is_a_no_valid, is_b_no_valid;
 	int i;
 
 	float el_store_a_co[3], el_store_b_co[3];
@@ -559,20 +560,30 @@ static void bm_edgering_pair_interpolate(BMesh *bm, LoopPairStore *lpair,
 	BM_edgeloop_calc_center(bm, el_store_a);
 	BM_edgeloop_calc_center(bm, el_store_b);
 
-	BM_edgeloop_calc_normal(bm, el_store_a);
-	BM_edgeloop_calc_normal(bm, el_store_b);
+	is_a_no_valid = BM_edgeloop_calc_normal(bm, el_store_a);
+	is_b_no_valid = BM_edgeloop_calc_normal(bm, el_store_b);
 
 	copy_v3_v3(el_store_a_co, BM_edgeloop_center_get(el_store_a));
 	copy_v3_v3(el_store_b_co, BM_edgeloop_center_get(el_store_b));
 
-	copy_v3_v3(el_store_a_no, BM_edgeloop_normal_get(el_store_a));
-	copy_v3_v3(el_store_b_no, BM_edgeloop_normal_get(el_store_b));
-
 	/* correct normals need to be flipped to face each other
 	 * we know both normals point in the same direction so one will need flipping */
 	{
 		float el_dir[3];
+		float no[3];
 		sub_v3_v3v3(el_dir, el_store_a_co, el_store_b_co);
+		normalize_v3_v3(no, el_dir);
+
+		if (is_a_no_valid == false) {
+			is_a_no_valid = BM_edgeloop_calc_normal_aligned(bm, el_store_a, no);
+		}
+		if (is_b_no_valid == false) {
+			is_b_no_valid = BM_edgeloop_calc_normal_aligned(bm, el_store_b, no);
+		}
+		(void)is_a_no_valid, (void)is_b_no_valid;
+
+		copy_v3_v3(el_store_a_no, BM_edgeloop_normal_get(el_store_a));
+		copy_v3_v3(el_store_b_no, BM_edgeloop_normal_get(el_store_b));
 
 		if (dot_v3v3(el_store_a_no, el_dir) > 0.0f) {
 			negate_v3(el_store_a_no);