fix [#35578] New bridge tool; bowtie crossing when destination edges form one half of an 'X'

3 files changed, 66 insertions, 1 deletions

diff --git a/source/blender/bmesh/intern/bmesh_edgeloop.c b/source/blender/bmesh/intern/bmesh_edgeloop.c
index 816b2a1547e..294cf23c613 100644
--- a/source/blender/bmesh/intern/bmesh_edgeloop.c
+++ b/source/blender/bmesh/intern/bmesh_edgeloop.c
@@ -383,6 +383,14 @@ void BM_mesh_edgeloops_calc_normal(BMesh *bm, ListBase *eloops)
 	}
 }
 
+void BM_mesh_edgeloops_calc_normal_aligned(BMesh *bm, ListBase *eloops, const float no_align[3])
+{
+	BMEdgeLoopStore *el_store;
+	for (el_store = eloops->first; el_store; el_store = el_store->next) {
+		BM_edgeloop_calc_normal_aligned(bm, el_store, no_align);
+	}
+}
+
 void BM_mesh_edgeloops_calc_order(BMesh *UNUSED(bm), ListBase *eloops, const bool use_normals)
 {
 	ListBase eloops_ordered = {NULL};
@@ -574,6 +582,8 @@ void BM_edgeloop_calc_normal(BMesh *UNUSED(bm), BMEdgeLoopStore *el_store)
 	float const *v_prev = NODE_AS_CO(el_store->verts.last);
 	float const *v_curr = NODE_AS_CO(node_curr);
 
+	zero_v3(el_store->no);
+
 	/* Newell's Method */
 	do {
 		add_newell_cross_v3_v3v3(el_store->no, v_prev, v_curr);
@@ -592,6 +602,43 @@ void BM_edgeloop_calc_normal(BMesh *UNUSED(bm), BMEdgeLoopStore *el_store)
 	}
 }
 
+/**
+ * For open loops that are stright lines,
+ * calculating the normal as if it were a polygon is meaningless.
+ *
+ * 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])
+{
+	LinkData *node_curr = el_store->verts.first;
+	float const *v_prev = NODE_AS_CO(el_store->verts.last);
+	float const *v_curr = NODE_AS_CO(node_curr);
+
+	zero_v3(el_store->no);
+
+	/* Own Method */
+	do {
+		float cross[3], no[3], dir[3];
+		sub_v3_v3v3(dir, v_curr, v_prev);
+		cross_v3_v3v3(cross, no_align, dir);
+		cross_v3_v3v3(no, dir, cross);
+		add_v3_v3(el_store->no, no);
+
+		if ((node_curr = node_curr->next)) {
+			v_prev = v_curr;
+			v_curr = NODE_AS_CO(node_curr);
+		}
+		else {
+			break;
+		}
+	} while (true);
+
+	if (UNLIKELY(normalize_v3(el_store->no) == 0.0f)) {
+		el_store->no[2] = 1.0f; /* other axis set to 0.0 */
+	}
+}
+
+
 
 void BM_edgeloop_flip(BMesh *UNUSED(bm), BMEdgeLoopStore *el_store)
 {
diff --git a/source/blender/bmesh/intern/bmesh_edgeloop.h b/source/blender/bmesh/intern/bmesh_edgeloop.h
index fcb8b4869f2..70c30ec73bd 100644
--- a/source/blender/bmesh/intern/bmesh_edgeloop.h
+++ b/source/blender/bmesh/intern/bmesh_edgeloop.h
@@ -41,6 +41,8 @@ bool                BM_mesh_edgeloops_find_path(BMesh *bm, ListBase *r_eloops,
 void                BM_mesh_edgeloops_free(struct ListBase *eloops);
 void                BM_mesh_edgeloops_calc_center(BMesh *bm, struct ListBase *eloops);
 void                BM_mesh_edgeloops_calc_normal(BMesh *bm, struct ListBase *eloops);
+void                BM_mesh_edgeloops_calc_normal_aligned(BMesh *bm, struct ListBase *eloops,
+                                                          const float no_align[3]);
 void                BM_mesh_edgeloops_calc_order(BMesh *UNUSED(bm), ListBase *eloops, const bool use_normals);
 
 
@@ -57,6 +59,8 @@ 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,
+                                                    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_bridge.c b/source/blender/bmesh/operators/bmo_bridge.c
index 53bb88aee0a..9da6e812032 100644
--- a/source/blender/bmesh/operators/bmo_bridge.c
+++ b/source/blender/bmesh/operators/bmo_bridge.c
@@ -168,6 +168,21 @@ static void bridge_loop_pair(BMesh *bm,
 	}
 
 	sub_v3_v3v3(el_dir, BM_edgeloop_center_get(el_store_a), BM_edgeloop_center_get(el_store_b));
+
+	if (is_closed) {
+		/* if all loops are closed this will calculate twice for all loops */
+		BM_edgeloop_calc_normal(bm, el_store_a);
+		BM_edgeloop_calc_normal(bm, el_store_b);
+	}
+	else {
+		/* normalizing isn't strictly needed but without we may get very large values */
+		float no[3];
+		normalize_v3_v3(no, el_dir);
+		BM_edgeloop_calc_normal_aligned(bm, el_store_a, no);
+		negate_v3(no);
+		BM_edgeloop_calc_normal_aligned(bm, el_store_b, no);
+	}
+
 	if ((dot_v3v3(BM_edgeloop_normal_get(el_store_a), el_dir) < 0.0f) !=
 		(dot_v3v3(BM_edgeloop_normal_get(el_store_b), el_dir) < 0.0f))
 	{
@@ -426,7 +441,6 @@ void bmo_bridge_loops_exec(BMesh *bm, BMOperator *op)
 
 	count = BM_mesh_edgeloops_find(bm, &eloops, bm_edge_test_cb, bm);
 
-	BM_mesh_edgeloops_calc_normal(bm, &eloops);
 	BM_mesh_edgeloops_calc_center(bm, &eloops);
 
 	if (count < 2) {