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, 117 insertions, 0 deletions

diff --git a/intern/opensubdiv/opensubdiv_evaluator_capi.h b/intern/opensubdiv/opensubdiv_evaluator_capi.h
new file mode 100644
index 00000000000..07a55cfd349
--- /dev/null
+++ b/intern/opensubdiv/opensubdiv_evaluator_capi.h
@@ -0,0 +1,117 @@
+// 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_EVALUATOR_CAPI_H_
+#define OPENSUBDIV_EVALUATOR_CAPI_H_
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+struct OpenSubdiv_EvaluatorInternal;
+struct OpenSubdiv_TopologyRefiner;
+
+typedef struct OpenSubdiv_Evaluator {
+  // Set coarse positions from a continuous array of coordinates.
+  void (*setCoarsePositions)(struct OpenSubdiv_Evaluator* evaluator,
+                             const float* positions,
+                             const int start_vertex_index,
+                             const int num_vertices);
+  // Set varying data from a continuous array of data.
+  void (*setVaryingData)(struct OpenSubdiv_Evaluator* evaluator,
+                         const float* varying_data,
+                         const int start_vertex_index, const int num_vertices);
+  // Set face varying data from a continuous array of data.
+  //
+  // TODO(sergey): Find a better name for vertex here. It is not the vertex of
+  // geometry, but a vertex of UV map.
+  void (*setFaceVaryingData)(struct OpenSubdiv_Evaluator* evaluator,
+                             const float* face_varying_data,
+                             const int start_vertex_index,
+                             const int num_vertices);
+
+  // Set coarse vertex position from a continuous memory buffer where
+  // first coordinate starts at offset of `start_offset` and there is `stride`
+  // bytes between adjacent vertex coordinates.
+  void (*setCoarsePositionsFromBuffer)(struct OpenSubdiv_Evaluator* evaluator,
+                                       const void* buffer,
+                                       const int start_offset,
+                                       const int stride,
+                                       const int start_vertex_index,
+                                       const int num_vertices);
+  // Set varying data from a continuous memory buffer where
+  // first coordinate starts at offset of `start_offset` and there is `stride`
+  // bytes between adjacent vertex coordinates.
+  void (*setVaryingDataFromBuffer)(struct OpenSubdiv_Evaluator* evaluator,
+                                   const void* buffer,
+                                   const int start_offset,
+                                   const int stride,
+                                   const int start_vertex_index,
+                                   const int num_vertices);
+  // Set face varying data from a continuous memory buffer where
+  // first coordinate starts at offset of `start_offset` and there is `stride`
+  // bytes between adjacent vertex coordinates.
+  //
+  // TODO(sergey): Find a better name for vertex here. It is not the vertex of
+  // geometry, but a vertex of UV map.
+  void (*setFaceVaryingDataFromBuffer)(struct OpenSubdiv_Evaluator* evaluator,
+                                       const void* buffer,
+                                       const int start_offset,
+                                       const int stride,
+                                       const int start_vertex_index,
+                                       const int num_vertices);
+
+  // Refine after coarse positions update.
+  void (*refine)(struct OpenSubdiv_Evaluator* evaluator);
+
+  // Evaluate given ptex face at given bilinear coordinate.
+  // If derivatives are NULL, they will not be evaluated.
+  void (*evaluateLimit)(struct OpenSubdiv_Evaluator* evaluator,
+                        const int ptex_face_index,
+                        float face_u, float face_v,
+                        float P[3], float dPdu[3], float dPdv[3]);
+
+  // Evaluate varying data at a given bilinear coordinate of given ptex face.
+  void (*evaluateVarying)(struct OpenSubdiv_Evaluator* evaluator,
+                          const int ptex_face_index,
+                          float face_u, float face_v,
+                          float varying[3]);
+
+  // Evaluate face-varying data at a given bilinear coordinate of given
+  // ptex face.
+  void (*evaluateFaceVarying)(struct OpenSubdiv_Evaluator* evaluator,
+                              const int ptex_face_index,
+                              float face_u, float face_v,
+                              float face_varying[2]);
+
+  // Internal storage for the use in this module only.
+  //
+  // This is where actual OpenSubdiv's evaluator is living.
+  struct OpenSubdiv_EvaluatorInternal* internal;
+} OpenSubdiv_Evaluator;
+
+OpenSubdiv_Evaluator* openSubdiv_createEvaluatorFromTopologyRefiner(
+    struct OpenSubdiv_TopologyRefiner* topology_refiner);
+
+void openSubdiv_deleteEvaluator(OpenSubdiv_Evaluator* evaluator);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif  // OPENSUBDIV_EVALUATOR_CAPI_H_