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#ifndef OSD_GL_DRAW_CONTEXT_H
#define OSD_GL_DRAW_CONTEXT_H

#if defined(__APPLE__)
    #include "TargetConditionals.h"
    #if TARGET_OS_IPHONE or TARGET_IPHONE_SIMULATOR
        #include <OpenGLES/ES2/gl.h>
    #else
        #include <OpenGL/gl3.h>
    #endif
#elif defined(ANDROID)
    #include <GLES2/gl2.h>
#else
    #if defined(_WIN32)
        #include <windows.h>
    #endif
    #include <GL/gl.h>
#endif

#include "../version.h"

#include "../far/mesh.h"
#include "../osd/drawContext.h"
#include "../osd/drawRegistry.h"
#include "../osd/vertex.h"

#include <map>

namespace OpenSubdiv {
namespace OPENSUBDIV_VERSION {

class OsdGLDrawContext : public OsdDrawContext {
public:
    typedef GLuint VertexBufferBinding;

    OsdGLDrawContext();
    virtual ~OsdGLDrawContext();

    template<class VERTEX_BUFFER>
    static OsdGLDrawContext *
    Create(FarMesh<OsdVertex> *farMesh,
           VERTEX_BUFFER *vertexBuffer,
           bool requirePtexCoordinates=false,
           bool requireFVarData=false) {

        if (not vertexBuffer) 
            return NULL;

        OsdGLDrawContext * instance = new OsdGLDrawContext();
        if (instance->allocate(farMesh,
                               vertexBuffer->BindVBO(),
                               vertexBuffer->GetNumElements(),
                               requirePtexCoordinates,
                               requireFVarData)) return instance;
        delete instance;
        return NULL;
    }

    GLuint patchIndexBuffer;

#if defined(GL_ES_VERSION_2_0)
    GLuint patchTrianglesIndexBuffer;
#endif

    GLuint ptexCoordinateTextureBuffer;
    GLuint fvarDataTextureBuffer;

    GLuint vertexTextureBuffer;
    GLuint vertexValenceTextureBuffer;
    GLuint quadOffsetTextureBuffer;
    GLuint patchLevelTextureBuffer;

    /// true if the GL version detected supports shader tessellation
    static bool SupportsAdaptiveTessellation();

private:
    bool allocate(FarMesh<OsdVertex> *farMesh,
                  GLuint vbo, int numElements,
                  bool requirePtexCoordinates,
                  bool requireFVarData);

    void _AppendPatchArray(
                int *indexBase, int *levelBase,
                FarPatchTables::PTable const & ptable, int patchSize,
                FarPatchTables::PtexCoordinateTable const & ptexTable,
                FarPatchTables::FVarDataTable const & fvarTable, int fvarDataWidth,
                OsdPatchDescriptor const & desc,
                int gregoryQuadOffsetBase);
};

} // end namespace OPENSUBDIV_VERSION
using namespace OPENSUBDIV_VERSION;

} // end namespace OpenSubdiv

#endif /* OSD_DRAW_CONTEXT_H */