//
//   Copyright 2013 Pixar
//
//   Licensed under the terms set forth in the LICENSE.txt file available at
//   https://opensubdiv.org/license.
//

#ifndef OPENSUBDIV3_OSD_CL_GL_VERTEX_BUFFER_H
#define OPENSUBDIV3_OSD_CL_GL_VERTEX_BUFFER_H

#include "../version.h"

#include "../osd/opencl.h"

namespace OpenSubdiv {
namespace OPENSUBDIV_VERSION {

namespace Osd {

///
/// \brief Concrete vertex buffer class for OpenCL subdivision and OpenGL drawing.
///
/// CLGLVertexBuffer implements CLVertexBufferInterface and
/// GLVertexBufferInterface.
///
/// The buffer interop between OpenCL and GL is handled automatically when a
/// client calls BindCLBuffer and BindVBO methods.
///
class CLGLVertexBuffer {
public:
    using ID = unsigned int;    // GLuint resource ID

    /// Creator. Returns NULL if error.
    static CLGLVertexBuffer * Create(int numElements,
                                     int numVertices,
                                     cl_context clContext);

    template <typename DEVICE_CONTEXT>
    static CLGLVertexBuffer * Create(int numElements, int numVertices,
                                     DEVICE_CONTEXT context) {
        return Create(numElements, numVertices, context->GetContext());
    }

    /// Destructor.
    ~CLGLVertexBuffer();

    /// This method is meant to be used in client code in order to provide
    /// coarse vertices data to Osd.
    void UpdateData(const float *src, int startVertex, int numVertices,
                    cl_command_queue clQueue);

    template<typename DEVICE_CONTEXT>
    void UpdateData(const float *src, int startVertex, int numVertices,
                    DEVICE_CONTEXT context) {
        UpdateData(src, startVertex, numVertices, context->GetCommandQueue());
    }

    /// Returns how many elements defined in this vertex buffer.
    int GetNumElements() const;

    /// Returns how many vertices allocated in this vertex buffer.
    int GetNumVertices() const;

    /// Returns the CL memory object. GL buffer will be mapped to CL memory
    /// space if necessary.
    cl_mem BindCLBuffer(cl_command_queue queue);

    /// Returns the GL buffer object. If the buffer is mapped to CL memory
    /// space, it will be unmapped back to GL.
    ID BindVBO(void *deviceContext = NULL);

protected:
    /// Constructor.
    CLGLVertexBuffer(int numElements, int numVertices, cl_context clContext);

    /// Allocates VBO for this buffer and register as a CL resource.
    /// Returns true if success.
    bool allocate(cl_context clContext);

    /// Acquires a resource from GL.
    void map(cl_command_queue queue);

    /// Releases a resource to GL.
    void unmap();

private:
    int _numElements;
    int _numVertices;
    ID _vbo;
    cl_command_queue _clQueue;
    cl_mem _clMemory;

    bool _clMapped;
};

}  // end namespace Osd

}  // end namespace OPENSUBDIV_VERSION
using namespace OPENSUBDIV_VERSION;

}  // end namespace OpenSubdiv

#endif  // OPENSUBDIV3_OSD_CL_GL_VERTEX_BUFFER_H