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.

3 files changed, 247 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
index 00000000000..b1acf43ad25
--- /dev/null
+++ b/source/blender/blenkernel/BKE_subdiv_ccg.h
@@ -0,0 +1,118 @@
+/*
+ * ***** 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__ */
diff --git a/source/blender/blenkernel/CMakeLists.txt b/source/blender/blenkernel/CMakeLists.txt
index deb2cb3bac5..85c9a2de4d7 100644
--- a/source/blender/blenkernel/CMakeLists.txt
+++ b/source/blender/blenkernel/CMakeLists.txt
@@ -194,6 +194,7 @@ set(SRC
 	intern/speaker.c
 	intern/studiolight.c
 	intern/subdiv.c
+	intern/subdiv_ccg.c
 	intern/subdiv_converter.c
 	intern/subdiv_converter_mesh.c
 	intern/subdiv_displacement.c
@@ -325,6 +326,7 @@ set(SRC
 	BKE_speaker.h
 	BKE_studiolight.h
 	BKE_subdiv.h
+	BKE_subdiv_ccg.h
 	BKE_subdiv_eval.h
 	BKE_subdiv_foreach.h
 	BKE_subdiv_mesh.h
diff --git a/source/blender/blenkernel/intern/subdiv_ccg.c b/source/blender/blenkernel/intern/subdiv_ccg.c
new file mode 100644
index 00000000000..647869dca7e
--- /dev/null
+++ b/source/blender/blenkernel/intern/subdiv_ccg.c
@@ -0,0 +1,127 @@
+/*
+ * ***** 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 blender/blenkernel/intern/subdiv_ccg.c
+ *  \ingroup bke
+ */
+
+#include "BKE_subdiv_ccg.h"
+
+#include "DNA_mesh_types.h"
+#include "DNA_meshdata_types.h"
+
+#include "MEM_guardedalloc.h"
+
+#include "BKE_ccg.h"
+#include "BKE_subdiv.h"
+
+static void subdiv_ccg_init_layers(SubdivCCG *subdiv_ccg,
+                                   const SubdivToCCGSettings *settings)
+{
+	/* CCG always contains coordinates. Rest of layers are coming after them. */
+	int layer_offset = sizeof(float) * 3;
+	/* Normals. */
+	if (settings->need_normal) {
+		subdiv_ccg->has_normal = true;
+		subdiv_ccg->normal_offset = layer_offset;
+		layer_offset += sizeof(float) * 3;
+	}
+	else {
+		subdiv_ccg->has_normal = false;
+		subdiv_ccg->normal_offset = -1;
+	}
+	/* Mask. */
+	if (settings->need_mask) {
+		subdiv_ccg->has_mask = true;
+		subdiv_ccg->mask_offset = layer_offset;
+		layer_offset += sizeof(float);
+	}
+	else {
+		subdiv_ccg->has_mask = false;
+		subdiv_ccg->mask_offset = -1;
+	}
+}
+
+static int grid_size_for_level_get(const SubdivCCG *subdiv_ccg, int level)
+{
+	BLI_assert(level >= 1);
+	BLI_assert(level <= subdiv_ccg->level);
+	return (1 << (level - 1)) + 1;
+}
+
+/* Per-vertex element size in bytes. */
+static int element_size_get(const SubdivCCG *subdiv_ccg)
+{
+	/* We always have 3 floats for coordinate. */
+	int num_floats = 3;
+	if (subdiv_ccg->has_normal) {
+		num_floats += 3;
+	}
+	if (subdiv_ccg->has_mask) {
+		num_floats += 1;
+	}
+	return sizeof(float) * num_floats;
+}
+
+SubdivCCG *BKE_subdiv_to_ccg(
+        Subdiv *UNUSED(subdiv),
+        const SubdivToCCGSettings *settings,
+        const Mesh *UNUSED(coarse_mesh))
+{
+	SubdivCCG *subdiv_ccg = MEM_callocN(sizeof(SubdivCCG *), "subdiv ccg");
+	subdiv_ccg->level = settings->resolution >> 1;
+	subdiv_ccg->grid_size =
+	        grid_size_for_level_get(subdiv_ccg, subdiv_ccg->level);
+	subdiv_ccg_init_layers(subdiv_ccg, settings);
+	return NULL;
+}
+
+void BKE_subdiv_ccg_destroy(SubdivCCG *subdiv_ccg)
+{
+	MEM_SAFE_FREE(subdiv_ccg->grids);
+	MEM_SAFE_FREE(subdiv_ccg->edges);
+	MEM_SAFE_FREE(subdiv_ccg->vertices);
+	MEM_freeN(subdiv_ccg);
+}
+
+void BKE_subdiv_ccg_key(CCGKey *key, const SubdivCCG *subdiv_ccg, int level)
+{
+	key->level = level;
+	key->elem_size = element_size_get(subdiv_ccg);
+	key->grid_size = grid_size_for_level_get(subdiv_ccg, level);
+	key->grid_area = key->grid_size * key->grid_size;
+	key->grid_bytes = key->elem_size * key->grid_area;
+
+	key->normal_offset = subdiv_ccg->normal_offset;
+	key->mask_offset = subdiv_ccg->mask_offset;
+
+	key->has_normals = subdiv_ccg->has_normal;
+	key->has_mask = subdiv_ccg->has_mask;
+}
+
+void BKE_subdiv_ccg_key_top_level(CCGKey *key, const SubdivCCG *subdiv_ccg)
+{
+	BKE_subdiv_ccg_key(key, subdiv_ccg, subdiv_ccg->level);
+}