Utility function to get poly -> looptri mapping

2 files changed, 36 insertions, 1 deletions

diff --git a/source/blender/blenkernel/BKE_mesh_mapping.h b/source/blender/blenkernel/BKE_mesh_mapping.h
index 633bd8a2dba..c8a17008f5d 100644
--- a/source/blender/blenkernel/BKE_mesh_mapping.h
+++ b/source/blender/blenkernel/BKE_mesh_mapping.h
@@ -36,6 +36,7 @@ struct MEdge;
 struct MPoly;
 struct MLoop;
 struct MLoopUV;
+struct MLoopTri;
 
 /* map from uv vertex to face (for select linked, stitch, uv suburf) */
 
@@ -127,7 +128,10 @@ void BKE_mesh_origindex_map_create(
         MeshElemMap **r_map, int **r_mem,
         const int totorig,
         const int *final_origindex, const int totfinal);
-
+void BKE_mesh_origindex_map_create_looptri(
+        MeshElemMap **r_map, int **r_mem,
+        const struct MPoly *mpoly, const int mpoly_num,
+        const struct MLoopTri *looptri, const int looptri_num);
 
 /* islands */
 
diff --git a/source/blender/blenkernel/intern/mesh_mapping.c b/source/blender/blenkernel/intern/mesh_mapping.c
index 1d8978586b6..c03f1feef9c 100644
--- a/source/blender/blenkernel/intern/mesh_mapping.c
+++ b/source/blender/blenkernel/intern/mesh_mapping.c
@@ -406,6 +406,37 @@ void BKE_mesh_origindex_map_create(MeshElemMap **r_map, int **r_mem,
 	*r_mem = indices;
 }
 
+/**
+ * A version of #BKE_mesh_origindex_map_create that takes a looptri array.
+ * Making a poly -> looptri map.
+ */
+void BKE_mesh_origindex_map_create_looptri(
+        MeshElemMap **r_map, int **r_mem,
+        const MPoly *mpoly, const int mpoly_num,
+        const MLoopTri *looptri, const int looptri_num)
+{
+	MeshElemMap *map = MEM_callocN(sizeof(MeshElemMap) * (size_t)mpoly_num, "poly-tessface map");
+	int *indices = MEM_mallocN(sizeof(int) * (size_t)looptri_num, "poly-tessface map mem");
+	int *index_step;
+	int i;
+
+	/* create offsets */
+	index_step = indices;
+	for (i = 0; i < mpoly_num; i++) {
+		map[i].indices = index_step;
+		index_step += ME_POLY_TRI_TOT(&mpoly[i]);
+	}
+
+	/* assign poly-tessface users */
+	for (i = 0; i < looptri_num; i++) {
+		MeshElemMap *map_ele = &map[looptri[i].poly];
+		map_ele->indices[map_ele->count++] = i;
+	}
+
+	*r_map = map;
+	*r_mem = indices;
+}
+
 /** \} */