Subsurf: Begin new subdivision surface module

The idea is to use this as a replacement of old CCG, now it is
based on OpenSubdiv. The goal is to reduce any possible overhead
which was happening with OpenSubdiv used by CCG.

Currently implemented/supported:

- Creation from mesh, including topology on OpenSubdiv side,
  its refinement.

- Evaluation of limit point, first order derivatives, normal,
  and face-varying data for individual coarse position.

- Evaluation of whole patches.

  Currently not optimized, uses evaluation of individual coarse
  positions.

- Creation of Mesh from subdiv, with all geometry being real:
  all mvert, medge, mloop, and mpoly.

  This includes custom data interpolation, but all faces currently
  are getting separated (they are converted to ptex patches, which
  we need to weld back together).

Still need to support lighter weights grids and such, but this
is already a required part to have subsurf working in the middle
of modifier stack.

Annoying part is ifdef all over the place, to keep it compilable
when OpenSubdiv is disabled. More cleaner approach would be to
have stub API for OpenSubdiv, so everything gets ifdef-ed in a
much fewer places.

1 files changed, 184 insertions, 0 deletions

diff --git a/source/blender/blenkernel/BKE_subdiv.h b/source/blender/blenkernel/BKE_subdiv.h
new file mode 100644
index 00000000000..92fb1167f55
--- /dev/null
+++ b/source/blender/blenkernel/BKE_subdiv.h
@@ -0,0 +1,184 @@
+/*
+ * ***** BEGIN GPL LICENSE BLOCK *****
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ *
+ * The Original Code is Copyright (C) 2018 by Blender Foundation.
+ * All rights reserved.
+ *
+ * Contributor(s): Sergey Sharybin.
+ *
+ * ***** END GPL LICENSE BLOCK *****
+ */
+#ifndef __BKE_SUBDIV_H__
+#define __BKE_SUBDIV_H__
+
+#include "BLI_sys_types.h"
+
+struct Mesh;
+struct OpenSubdiv_Converter;
+struct OpenSubdiv_Evaluator;
+struct OpenSubdiv_TopologyRefiner;
+
+/** \file BKE_subdiv.h
+ *  \ingroup bke
+ *  \since July 2018
+ *  \author Sergey Sharybin
+ */
+
+typedef enum {
+	SUBDIV_FVAR_LINEAR_INTERPOLATION_NONE,
+	SUBDIV_FVAR_LINEAR_INTERPOLATION_CORNERS_ONLY,
+	SUBDIV_FVAR_LINEAR_INTERPOLATION_BOUNDARIES,
+	SUBDIV_FVAR_LINEAR_INTERPOLATION_ALL,
+} eSubdivFVarLinearInterpolation;
+
+typedef struct SubdivSettings {
+	bool is_simple;
+	bool is_adaptive;
+	int level;
+	eSubdivFVarLinearInterpolation fvar_linear_interpolation;
+} SubdivSettings;
+
+typedef struct Subdiv {
+	/* Settings this subdivision surface is created for.
+	 *
+	 * It is read-only after assignment in BKE_subdiv_new_from_FOO().
+	 */
+	SubdivSettings settings;
+
+	/* Total number of ptex faces on subdivision level 0.
+	 *
+	 * Ptex face is what is internally used by OpenSubdiv for evaluator. It is
+	 * a quad face, which corresponds to Blender's legacy Catmull Clark grids.
+	 *
+	 * Basically, here is a correspondence between polygons and ptex faces:
+	 * - Triangle consists of 3 PTex faces.
+	 * - Quad is a single PTex face.
+	 * - N-gon is N PTex faces.
+	 *
+	 * This value is initialized in BKE_subdiv_new_from_FOO() and is read-only
+	 * after this.
+	 */
+	int num_ptex_faces;
+
+	/* Indexed by base face index, element indicates total number of ptex faces
+	 * created for preceding base faces.
+	 */
+	int *face_ptex_offset;
+
+	/* Topology refiner includes all the glue logic to feed Blender side
+	 * topology to OpenSubdiv. It can be shared by both evaluator and GL mesh
+	 * drawer.
+	 */
+	struct OpenSubdiv_TopologyRefiner *topology_refiner;
+
+	/* CPU side evaluator. */
+	struct OpenSubdiv_Evaluator *evaluator;
+} Subdiv;
+
+/* ============================== CONSTRUCTION ============================== */
+
+Subdiv *BKE_subdiv_new_from_converter(const SubdivSettings *settings,
+                                      struct OpenSubdiv_Converter *converter);
+
+Subdiv *BKE_subdiv_new_from_mesh(const SubdivSettings *settings,
+                                 struct Mesh *mesh);
+
+void BKE_subdiv_free(Subdiv *subdiv);
+
+/* ============================= EVALUATION API ============================= */
+
+void BKE_subdiv_eval_begin(Subdiv *subdiv);
+void BKE_subdiv_eval_update_from_mesh(Subdiv *subdiv, const struct Mesh *mesh);
+
+/* Single point queries. */
+
+void BKE_subdiv_eval_limit_point(
+        Subdiv *subdiv,
+        const int ptex_face_index,
+        const float u, const float v,
+        float P[3]);
+void BKE_subdiv_eval_limit_point_and_derivatives(
+        Subdiv *subdiv,
+        const int ptex_face_index,
+        const float u, const float v,
+        float P[3], float dPdu[3], float dPdv[3]);
+void BKE_subdiv_eval_limit_point_and_normal(
+        Subdiv *subdiv,
+        const int ptex_face_index,
+        const float u, const float v,
+        float P[3], float N[3]);
+void BKE_subdiv_eval_limit_point_and_short_normal(
+        Subdiv *subdiv,
+        const int ptex_face_index,
+        const float u, const float v,
+        float P[3], short N[3]);
+
+void BKE_subdiv_eval_face_varying(
+        Subdiv *subdiv,
+        const int ptex_face_index,
+        const float u, const float v,
+        float varying[2]);
+
+/* Patch queries at given resolution.
+ *
+ * Will evaluate patch at uniformly distributed (u, v) coordinates on a grid
+ * of given resolution, producing resolution^2 evaluation points. The order
+ * goes as u in rows, v in columns.
+ */
+
+void BKE_subdiv_eval_limit_patch_resolution_point(
+        Subdiv *subdiv,
+        const int ptex_face_index,
+        const int resolution,
+        void *buffer, const int offset, const int stride);
+void BKE_subdiv_eval_limit_patch_resolution_point_and_derivatives(
+        Subdiv *subdiv,
+        const int ptex_face_index,
+        const int resolution,
+        void *point_buffer, const int point_offset, const int point_stride,
+        void *du_buffer, const int du_offset, const int du_stride,
+        void *dv_buffer, const int dv_offset, const int dv_stride);
+void BKE_subdiv_eval_limit_patch_resolution_point_and_normal(
+        Subdiv *subdiv,
+        const int ptex_face_index,
+        const int resolution,
+        void *point_buffer, const int point_offset, const int point_stride,
+        void *normal_buffer, const int normal_offset, const int normal_stride);
+void BKE_subdiv_eval_limit_patch_resolution_point_and_short_normal(
+        Subdiv *subdiv,
+        const int ptex_face_index,
+        const int resolution,
+        void *point_buffer, const int point_offset, const int point_stride,
+        void *normal_buffer, const int normal_offset, const int normal_stride);
+
+/* =========================== SUBDIV TO MESH API =========================== */
+
+typedef struct SubdivToMeshSettings {
+	/* Resolution at which ptex are being evaluated.
+	 * This defines how many vertices final mesh will have: every ptex has
+	 * resolution^2 vertices.
+	 */
+	int resolution;
+} SubdivToMeshSettings;
+
+/* Create real hi-res mesh from subdivision, all geometry is "real". */
+struct Mesh *BKE_subdiv_to_mesh(
+        Subdiv *subdiv,
+        const SubdivToMeshSettings *settings,
+        const struct Mesh *coarse_mesh);
+
+#endif  /* __BKE_SUBDIV_H__ */