Subdiv: Some ground work for CCG support

Nothing really interesting, just starting laying down API which
seems to be a decent substitute to CCGDM, without requiring too
much work be done in sculpting area.

1 files changed, 118 insertions, 0 deletions

diff --git a/source/blender/blenkernel/BKE_subdiv_ccg.h b/source/blender/blenkernel/BKE_subdiv_ccg.h
new file mode 100644
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+++ b/source/blender/blenkernel/BKE_subdiv_ccg.h
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+/*
+ * ***** 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 *****
+ */
+
+/** \file BKE_subdiv_ccg.h
+ *  \ingroup bke
+ *  \since July 2018
+ *  \author Sergey Sharybin
+ */
+
+#ifndef __BKE_SUBDIV_CCG_H__
+#define __BKE_SUBDIV_CCG_H__
+
+#include "BKE_customdata.h"
+#include "BLI_sys_types.h"
+
+struct CCGElem;
+struct CCGKey;
+struct Mesh;
+struct Subdiv;
+
+typedef struct SubdivToCCGSettings {
+	/* Resolution at which regular ptex (created for quad polygon) are being
+	 * evaluated. This defines how many vertices final mesh will have: every
+	 * regular ptex has resolution^2 vertices. Special (irregular, or ptex
+	 * crated for a corner of non-quad polygon) will have resolution of
+	 * `resolution - 1`.
+	 */
+	int resolution;
+	/* Denotes which extra layers to be added to CCG elements. */
+	bool need_normal;
+	bool need_mask;
+} SubdivToCCGSettings;
+
+/* Representation of subdivision surface which uses CCG grids. */
+typedef struct SubdivCCG {
+	/* A level at which geometry was subdivided. This is what defines grid
+	 * resolution. It is NOT the topology refinement level.
+	 */
+	int level;
+	/* Resolution of grid. All grids have matching resolution, and resolution
+	 * is same as ptex created for non-quad polygons.
+	 */
+	int grid_size;
+	/* Grids represent limit surface, with displacement applied. Grids are
+	 * corresponding to face-corners of coarse mesh, each grid has
+	 * grid_size^2 elements.
+	 */
+	struct CCGElem **grids;
+	int num_grids;
+	/* Loose edges, each array element contains grid_size elements
+	 * corresponding to vertices created by subdividing coarse edges.
+	 */
+	struct CCGElem **edges;
+	int num_edges;
+	/* Loose vertices. Every element corresponds to a loose vertex from a coarse
+	 * mesh, every coarse loose vertex corresponds to a single sundivided
+	 * element.
+	 */
+	struct CCGElem *vertices;
+	int num_vertices;
+	/* Denotes which layers present in the elements.
+	 *
+	 * Grids always has coordinates, followed by extra layers which are set to
+	 * truth here.
+	 */
+	bool has_normal;
+	bool has_mask;
+	/* Offsets of corresponding data layers in the elements. */
+	int normal_offset;
+	int mask_offset;
+
+	/* TODO(sergey): Consider adding some accessors to a "decoded" geometry,
+	 * to make integration with draw manager and such easy.
+	 */
+
+	/* TODO(sergey): Consider adding CD layers here, so we can draw final mesh
+	 * from grids, and have UVs and such work.
+	 */
+} SubdivCCG;
+
+/* Create real hi-res CCG from subdivision. */
+struct SubdivCCG *BKE_subdiv_to_ccg(
+        struct Subdiv *subdiv,
+        const SubdivToCCGSettings *settings,
+        const struct Mesh *coarse_mesh);
+
+/* Destroy CCG representation of subdivision surface. */
+void BKE_subdiv_ccg_destroy(SubdivCCG *subdiv_ccg);
+
+/* Create a key for accessing grid elements at a given level. */
+void BKE_subdiv_ccg_key(
+        struct CCGKey *key, const SubdivCCG *subdiv_ccg, int level);
+void BKE_subdiv_ccg_key_top_level(
+        struct CCGKey *key, const SubdivCCG *subdiv_ccg);
+
+#endif  /* __BKE_SUBDIV_CCG_H__ */