axmol/core/renderer/backend/opengl/BufferGL.h

/****************************************************************************
 Copyright (c) 2018-2019 Xiamen Yaji Software Co., Ltd.

 https://axmolengine.github.io/

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#pragma once

#include "../Buffer.h"
#include "platform/GL.h"
#include "base/EventListenerCustom.h"

#include <vector>

NS_AX_BACKEND_BEGIN
/**
 * @addtogroup _opengl
 * @{
 */

/**
 * Store vertex and index data.
 */
class BufferGL : public Buffer
{
public:
    /**
     * @param size Specifies the size in bytes of the buffer object's new data store.
     * @param type Specifies the target buffer object. The symbolic constant must be BufferType::VERTEX or
     * BufferType::INDEX.
     * @param usage Specifies the expected usage pattern of the data store. The symbolic constant must be
     * BufferUsage::STATIC, BufferUsage::DYNAMIC.
     */
    BufferGL(std::size_t size, BufferType type, BufferUsage usage);
    ~BufferGL();

    /**
     * @brief Update buffer data
     * @param data Specifies a pointer to data that will be copied into the data store for initialization.
     * @param size Specifies the size in bytes of the data store region being replaced.
     * @see `updateSubData(void* data, unsigned int offset, unsigned int size)`
     */
    virtual void updateData(void* data, std::size_t size) override;

    /**
     * @brief Update buffer sub-region data
     * @param data Specifies a pointer to the new data that will be copied into the data store.
     * @param offset Specifies the offset into the buffer object's data store where data replacement will begin,
     * measured in bytes.
     * @param size Specifies the size in bytes of the data store region being replaced.
     * @see `updateData(void* data, unsigned int size)`
     */
    virtual void updateSubData(void* data, std::size_t offset, std::size_t size) override;

    /**
     * Static buffer data will automatically stored when it comes to foreground.
     * This interface is used to indicate whether external data needs to be used to update the buffer(false) instead of
     * using the default stored data(true).
     * @param needDefaultStoredData Specifies whether to use the default stored data.
     */
    virtual void usingDefaultStoredData(bool needDefaultStoredData) override;

    /**
     * Get buffer object.
     * @return Buffer object.
     */
    inline GLuint getHandler() const { return _buffer; }

private:
#if AX_ENABLE_CACHE_TEXTURE_DATA
    void reloadBuffer();
    void fillBuffer(void* data, std::size_t offset, std::size_t size);

    bool _bufferAlreadyFilled                      = false;
    EventListenerCustom* _backToForegroundListener = nullptr;
#endif

    GLuint _buffer               = 0;
    std::size_t _bufferAllocated = 0;
    char* _data                  = nullptr;
    bool _needDefaultStoredData  = true;
};
// end of _opengl group
///> @}
NS_AX_BACKEND_END