Subsurf: Implement foreach traversal for subdivsion topology

This makes it more generic process to perform actions which
depend on ptex face + (u, v) and on subdivided vertex index.

Currently it is still just a subdivision calculation process,
but same foreach callbacks can easily be used to propagate
displacement from known vertex locations back to displacement
grids.

1 files changed, 144 insertions, 0 deletions

diff --git a/source/blender/blenkernel/BKE_subdiv.h b/source/blender/blenkernel/BKE_subdiv.h
index 9f8a0f261e6..76539383f16 100644
--- a/source/blender/blenkernel/BKE_subdiv.h
+++ b/source/blender/blenkernel/BKE_subdiv.h
@@ -35,6 +35,7 @@ struct OpenSubdiv_Converter;
 struct OpenSubdiv_Evaluator;
 struct OpenSubdiv_TopologyRefiner;
 struct Subdiv;
+struct SubdivToMeshSettings;
 
 /** \file BKE_subdiv.h
  *  \ingroup bke
@@ -252,6 +253,149 @@ void BKE_subdiv_eval_limit_patch_resolution_point_and_short_normal(
         void *point_buffer, const int point_offset, const int point_stride,
         void *normal_buffer, const int normal_offset, const int normal_stride);
 
+/* ========================== FOREACH/TRAVERSE API ========================== */
+
+struct SubdivForeachContext;
+
+typedef bool (*SubdivForeachTopologyInformationCb)(
+        const struct SubdivForeachContext *context,
+        const int num_vertices,
+        const int num_edges,
+        const int num_loops,
+        const int num_polygons);
+
+typedef void (*SubdivForeachVertexFromCornerCb)(
+        const struct SubdivForeachContext *context,
+        void *tls,
+        const int ptex_face_index,
+        const float u, const float v,
+        const int coarse_vertex_index,
+        const int coarse_poly_index,
+        const int coarse_corner,
+        const int subdiv_vertex_index);
+
+typedef void (*SubdivForeachVertexFromEdgeCb)(
+        const struct SubdivForeachContext *context,
+        void *tls,
+        const int ptex_face_index,
+        const float u, const float v,
+        const int coarse_edge_index,
+        const int coarse_poly_index,
+        const int coarse_corner,
+        const int subdiv_vertex_index);
+
+typedef void (*SubdivForeachVertexInnerCb)(
+        const struct SubdivForeachContext *context,
+        void *tls,
+        const int ptex_face_index,
+        const float u, const float v,
+        const int coarse_poly_index,
+        const int coarse_corner,
+        const int subdiv_vertex_index);
+
+typedef void (*SubdivForeachEdgeCb)(
+        const struct SubdivForeachContext *context,
+        void *tls,
+        const int coarse_edge_index,
+        const int subdiv_edge_index,
+        const int subdiv_v1, const int subdiv_v2);
+
+typedef void (*SubdivForeachLoopCb)(
+        const struct SubdivForeachContext *context,
+        void *tls,
+        const int ptex_face_index,
+        const float u, const float v,
+        const int coarse_loop_index,
+        const int coarse_poly_index,
+        const int coarse_corner,
+        const int subdiv_loop_index,
+        const int subdiv_vertex_index, const int subdiv_edge_index);
+
+typedef void (*SubdivForeachPolygonCb)(
+        const struct SubdivForeachContext *context,
+        void *tls,
+        const int coarse_poly_index,
+        const int subdiv_poly_index,
+        const int start_loop_index, const int num_loops);
+
+typedef void (*SubdivForeachLooseCb)(
+        const struct SubdivForeachContext *context,
+        void *tls,
+        const int coarse_vertex_index,
+        const int subdiv_vertex_index);
+
+typedef void (*SubdivForeachVertexOfLooseEdgeCb)(
+        const struct SubdivForeachContext *context,
+        void *tls,
+        const int coarse_edge_index,
+        const float u,
+        const int subdiv_vertex_index);
+
+typedef struct SubdivForeachContext {
+	/* Is called when topology information becomes available.
+	 * Is only called once.
+	 *
+	 * NOTE: If this callback returns false, the foreach loop is aborted.
+	 */
+	SubdivForeachTopologyInformationCb topology_info;
+	/* These callbacks are called from every ptex which shares "emitting"
+	 * vertex or edge.
+	 */
+	SubdivForeachVertexFromCornerCb vertex_every_corner;
+	SubdivForeachVertexFromEdgeCb vertex_every_edge;
+	/* Those callbacks are run once per subdivision vertex, ptex is undefined
+	 * as in it will be whatever first ptex face happened to be tarversed in
+	 * the multi-threaded environment ahd which shares "emitting" vertex or
+	 * edge.
+	 */
+	SubdivForeachVertexFromCornerCb vertex_corner;
+	SubdivForeachVertexFromEdgeCb vertex_edge;
+	/* Called exactly once, always corresponds to a single ptex face. */
+	SubdivForeachVertexInnerCb vertex_inner;
+	/* Called once for each loose vertex. One loose coarse vertexcorresponds
+	 * to a single subdivision vertex.
+	 */
+	SubdivForeachLooseCb vertex_loose;
+	/* Called once per vertex created for loose edge. */
+	SubdivForeachVertexOfLooseEdgeCb vertex_of_loose_edge;
+	/* NOTE: If subdivided edge does not come from coarse edge, ORIGINDEX_NONE
+	 * will be passed as coarse_edge_index.
+	 */
+	SubdivForeachEdgeCb edge;
+	/* NOTE: If subdivided loop does not come from coarse loop, ORIGINDEX_NONE
+	 * will be passed as coarse_loop_index.
+	 */
+	SubdivForeachLoopCb loop;
+	SubdivForeachPolygonCb poly;
+
+	/* User-defined pointer, to allow callbacks know something about context the
+	 * traversal is happening for,
+	 */
+	void *user_data;
+
+	/* Initial value of TLS data. */
+	void *user_data_tls;
+	/* Size of TLS data. */
+	size_t user_data_tls_size;
+	/* Function to free TLS storage. */
+	void (*user_data_tls_free)(void *tls);
+} SubdivForeachContext;
+
+/* Invokes callbacks in the order and with values which corresponds to creation
+ * of final subdivided mesh.
+ *
+ * Returns truth if the whole topology was traversed, without any early exits.
+ *
+ * TODO(sergey): Need to either get rid of subdiv or of coarse_mesh.
+ * The main point here is th be abel to get base level topology, which can be
+ * done with either of those. Having both of them is kind of redundant.
+ */
+bool BKE_subdiv_foreach_subdiv_geometry(
+        struct Subdiv *subdiv,
+        const struct SubdivForeachContext *context,
+        const struct SubdivToMeshSettings *mesh_settings,
+        const struct Mesh *coarse_mesh);
+
 /* =========================== SUBDIV TO MESH API =========================== */
 
 typedef struct SubdivToMeshSettings {