OpenSubdiv: Re-work C-API integration

Main goal is to make API simpler to follow (at least ion terms what
is defined/declared where, as opposite of handful big headers which
includes all the declarations), and also avoid a big set of long and
obscure functions.

Now C-API files are split into smaller ones, following OpenSubdiv
behavior more closely, and also function pointers in structures
used a lot more, which shortens functions names,

UV integration part in GL Mesh is mainly stripped away, it needs
to be done differently. On a related topic, UV coordinates API in
converter needs to be removed as well, we do not need coordinates,
only island connectivity information there.

Additional changes:

- Varying interpolation in evaluator API are temporarily disabled,
  need to extend API somewhere (probably, evaluator's API) to inform
  layout information of vertex data (whether it contains varying
  data, width, stride and such).

- Evaluator now can interpolate face-varying data.
  Only works for adaptive refiner, since some issues in OpenSubdiv
  itself.

Planned changes:

- Remove uv coordinates from TopologyConverter.
- Support evaluation of patches (as opposite to individual coordinates
  as it happens currently).
- Support more flexible layout of varying and face-varying data.
  It is stupid to assume varying is 3 floats and face-varying 2 floats.
- Support of second order derivatives.
- Everything else what i'm missing in this list.

1 files changed, 92 insertions, 0 deletions

diff --git a/intern/opensubdiv/opensubdiv_gl_mesh_capi.h b/intern/opensubdiv/opensubdiv_gl_mesh_capi.h
new file mode 100644
index 00000000000..971f6b9dcd3
--- /dev/null
+++ b/intern/opensubdiv/opensubdiv_gl_mesh_capi.h
@@ -0,0 +1,92 @@
+// Copyright 2013 Blender Foundation. All rights reserved.
+//
+// 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.
+//
+// Author: Sergey Sharybin
+
+#ifndef OPENSUBDIV_CAPI_GL_MESH_CAPI_H_
+#define OPENSUBDIV_CAPI_GL_MESH_CAPI_H_
+
+#include <stdint.h>  // for bool
+
+#include "opensubdiv_capi_type.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+struct OpenSubdiv_GLMeshInternal;
+
+// Mesh which is displayable in OpenGL context.
+typedef struct OpenSubdiv_GLMesh {
+  //////////////////////////////////////////////////////////////////////////////
+  // Subdivision/topology part.
+
+  // Returns the GL index buffer containing the patch control vertices.
+  unsigned int (*getPatchIndexBuffer)(struct OpenSubdiv_GLMesh* gl_mesh);
+
+  // Bind GL buffer which contains vertices (VBO).
+  // TODO(sergey): Is this a coarse vertices?
+  void (*bindVertexBuffer)(struct OpenSubdiv_GLMesh* gl_mesh);
+
+  // Set coarse positions from a continuous array of coordinates.
+  void (*setCoarsePositions)(struct OpenSubdiv_GLMesh* gl_mesh,
+                             const float* positions,
+                             const int start_vertex,
+                             const int num_vertices);
+  // TODO(sergey): setCoarsePositionsFromBuffer().
+
+  // Refine after coarse positions update.
+  void (*refine)(struct OpenSubdiv_GLMesh* gl_mesh);
+
+  // Synchronize after coarse positions update and refine.
+  void (*synchronize)(struct OpenSubdiv_GLMesh* gl_mesh);
+
+  //////////////////////////////////////////////////////////////////////////////
+  // Drawing part.
+
+  // Prepare mesh for display.
+  void (*prepareDraw)(struct OpenSubdiv_GLMesh* gl_mesh,
+                      const bool use_osd_glsl,
+                      const int active_uv_index);
+
+  // Draw given range of patches.
+  //
+  // If fill_quads is false, then patches are drawn in wireframe.
+  void (*drawPatches)(struct OpenSubdiv_GLMesh *gl_mesh,
+                      const bool fill_quads,
+                      const int start_patch, const int num_patches);
+
+  // Internal storage for the use in this module only.
+  //
+  // Tease: This contains an actual OpenSubdiv's Mesh object.
+  struct OpenSubdiv_GLMeshInternal* internal;
+} OpenSubdiv_GLMesh;
+
+OpenSubdiv_GLMesh* openSubdiv_createOsdGLMeshFromTopologyRefiner(
+    struct OpenSubdiv_TopologyRefiner* topology_refiner,
+    eOpenSubdivEvaluator evaluator_type);
+
+void openSubdiv_deleteOsdGLMesh(OpenSubdiv_GLMesh *gl_mesh);
+
+// Global resources needed for GL mesh drawing.
+bool openSubdiv_initGLMeshDrawingResources(void);
+void openSubdiv_deinitGLMeshDrawingResources(void);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif  // OPENSUBDIV_CAPI_GL_MESH_CAPI_H_