COpenGLBuffer.h

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/* +------------------------------------------------------------------------+
   |                     Mobile Robot Programming Toolkit (MRPT)            |
   |                          https://www.mrpt.org/                         |
   |                                                                        |
   | Copyright (c) 2005-2020, Individual contributors, see AUTHORS file     |
   | See: https://www.mrpt.org/Authors - All rights reserved.               |
   | Released under BSD License. See: https://www.mrpt.org/License          |
   +------------------------------------------------------------------------+ */
#pragma once

#include <memory>
#include <thread>

namespace mrpt::opengl
{
/** A wrapper for an OpenGL buffer object.
 * Refer to docs for glGenBuffers() and glBufferData().
 *
 * \ingroup mrpt_opengl_grp
 */
class COpenGLBuffer
{
   public:
    enum class Type : unsigned int
    {
        Vertex = 0x8892,  // GL_ARRAY_BUFFER (Default)
        ElementIndex = 0x8893,  // GL_ELEMENT_ARRAY_BUFFER
        PixelPack = 0x88EB,  // GL_PIXEL_PACK_BUFFER
        PixelUnpack = 0x88EC  // GL_PIXEL_UNPACK_BUFFER
    };

    enum class Usage : unsigned int
    {
        StreamDraw = 0x88E0,  // GL_STREAM_DRAW
        StreamRead = 0x88E1,  // GL_STREAM_READ
        StreamCopy = 0x88E2,  // GL_STREAM_COPY
        StaticDraw = 0x88E4,  // GL_STATIC_DRAW (Default)
        StaticRead = 0x88E5,  // GL_STATIC_READ
        StaticCopy = 0x88E6,  // GL_STATIC_COPY
        DynamicDraw = 0x88E8,  // GL_DYNAMIC_DRAW
        DynamicRead = 0x88E9,  // GL_DYNAMIC_READ
        DynamicCopy = 0x88EA  // GL_DYNAMIC_COPY
    };

    explicit COpenGLBuffer(const Type type);
    COpenGLBuffer() : COpenGLBuffer(Type::Vertex) {}
    ~COpenGLBuffer() = default;

    Type type() const { return m_impl->type; }

    Usage usage() const { return m_impl->usage; }
    void setUsage(const Usage u) { m_impl->usage = u; }

    /** Actually create the buffer, destroying any previously existing buffer.
     * Call after setting the type and usage. \sa allocate()
     */
    void create() { m_impl->create(); }

    /** Calls create() only if the buffer has not been created yet. */
    void createOnce()
    {
        if (!isCreated()) create();
    }
    bool isCreated() const { return m_impl->created; }

    /** Automatically called upon destructor, no need for the user to call it in
     * normal situations. */
    void destroy() { m_impl->destroy(); }

    void bind() { m_impl->bind(); }
    void release() { m_impl->bind(); }

    unsigned int bufferId() const { return m_impl->buffer_id; }

    /** Reserves byteCount bytes in the buffer and copy to it the provided data.
     * create() and bind() must be called before using this method.
     */
    void allocate(const void* data, int byteCount)
    {
        m_impl->allocate(data, byteCount);
    }

   private:
    struct RAII_Impl
    {
        RAII_Impl(COpenGLBuffer::Type t);
        ~RAII_Impl();

        COpenGLBuffer::Type type;
        COpenGLBuffer::Usage usage = COpenGLBuffer::Usage::StaticDraw;

        void create();
        void destroy();
        void bind();
        void release();
        void allocate(const void* data, int byteCount);

        bool created = false;
        unsigned int buffer_id = 0;
        std::thread::id created_from;
    };
    std::shared_ptr<RAII_Impl> m_impl;
};

// For use in glVertexAttribPointer()
#define BUFFER_OFFSET(offset) (reinterpret_cast<GLvoid*>(offset))

}  // namespace mrpt::opengl