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, 57 insertions, 0 deletions

diff --git a/source/blender/blenkernel/intern/subdiv_converter.h b/source/blender/blenkernel/intern/subdiv_converter.h
new file mode 100644
index 00000000000..748d97f4178
--- /dev/null
+++ b/source/blender/blenkernel/intern/subdiv_converter.h
@@ -0,0 +1,57 @@
+/*
+ * ***** 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_CONVERTER_H__
+#define __BKE_SUBDIV_CONVERTER_H__
+
+#include "BKE_subdiv.h"
+
+/* NOTE: Was initially used to get proper enumerator types, but this makes
+ * it tricky to compile without OpenSubdiv.
+ */
+/* #include "opensubdiv_converter_capi.h" */
+
+struct Mesh;
+struct OpenSubdiv_Converter;
+struct SubdivSettings;
+
+void BKE_subdiv_converter_init_for_mesh(struct OpenSubdiv_Converter *converter,
+                                        const struct SubdivSettings *settings,
+                                        const struct Mesh *mesh);
+
+/* NOTE: Frees converter data, but not converter itself. This means, that if
+ * converter was allocated on heap, it is up to the user to free that memory.
+ */
+void BKE_subdiv_converter_free(struct OpenSubdiv_Converter *converter);
+
+/* ============================ INTERNAL HELPERS ============================ */
+
+/* TODO(sergey): Find a way to make it OpenSubdiv_FVarLinearInterpolation,
+ * without breaking compilation without OpenSubdiv.
+ */
+int BKE_subdiv_converter_fvar_linear_from_settings(
+        const SubdivSettings *settings);
+
+#endif  /* __BKE_SUBDIV_CONVERTER_H__ */