axmol/cocos/renderer/backend/Texture.h

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

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#pragma once

#include "Types.h"
#include "base/CCRef.h"
#include <cassert>

#include <functional>

CC_BACKEND_BEGIN
/**
 * @addtogroup _backend
 * @{
 */

/**
 * Store texture description.
 */
struct TextureDescriptor
{
    TextureType textureType = TextureType::TEXTURE_2D;
    PixelFormat textureFormat = PixelFormat::RGBA8888;
    TextureUsage textureUsage = TextureUsage::READ;
    uint32_t width = 0;
    uint32_t height = 0;
    uint32_t depth = 0;
    SamplerDescriptor samplerDescriptor;
};

/**
 * A base texture
 */
class TextureBackend : public Ref
{
public:
    /**
     * Update sampler
     * @param sampler Specifies the sampler descriptor.
     */
    virtual void updateSamplerDescriptor(const SamplerDescriptor &sampler) = 0;
    
    /**
     * Read a block of pixels from the drawable texture
     * @param x,y Specify the window coordinates of the first pixel that is read from the drawable texture. This location is the lower left corner of a rectangular block of pixels.
     * @param width,height Specify the dimensions of the pixel rectangle. width and height of one correspond to a single pixel.
     * @param flipImage Specifies if needs to flip the image.
     * @param callback Specifies a call back function to deal with the image.
     */
    virtual void getBytes(std::size_t x, std::size_t y, std::size_t width, std::size_t height, bool flipImage, std::function<void(const unsigned char*, std::size_t, std::size_t)> callback) = 0;
    
    /// Generate mipmaps.
    virtual void generateMipmaps() = 0;

    /**
     * Update texture description.
     * @param descriptor Specifies texture and sampler descriptor.
     */
    virtual void updateTextureDescriptor(const TextureDescriptor& descriptor);

    /**
     * Get texture format.
     * @return Texture format.
     */
    inline PixelFormat getTextureFormat() const { return _textureFormat; }

    /**
     * Get texture usage. Symbolic constant can be READ, WRITE or RENDER_TARGET.
     * @return Texture usage.
     */
    inline TextureUsage getTextureUsage() const { return _textureUsage; }

    /**
     * Get texture type. Symbolic constant value can be either TEXTURE_2D or TEXTURE_CUBE.
     * @return Texture type.
     */
    inline TextureType getTextureType() const { return _textureType; }
    
    /**
     * Check if mipmap had generated before.
     * @return true if the mipmap has always generated before, otherwise false.
     */
    inline bool hasMipmaps() const { return _hasMipmaps; }

protected:
    /**
     * @param descriptor Specifies the texture descirptor.
     */
    TextureBackend(const TextureDescriptor& descriptor);
    virtual ~TextureBackend();
        
    /// The bytes of all components.
    uint8_t _bitsPerElement = 0;
    bool _hasMipmaps = false;
    bool _isCompressed = false;
    uint32_t _width = 0;
    uint32_t _height = 0;

    TextureType _textureType = TextureType::TEXTURE_2D;
    PixelFormat _textureFormat = PixelFormat::RGBA8888;
    TextureUsage _textureUsage = TextureUsage::READ;
};

/**
 * A 2D texture.
 */
class Texture2DBackend : public TextureBackend
{
public:
    /**
     * Update a two-dimensional texture image
     * @param data Specifies a pointer to the image data in memory.
     * @param width Specifies the width of the texture image.
     * @param height Specifies the height of the texture image.
     * @param level Specifies the level-of-detail number. Level 0 is the base image level. Level n is the nth mipmap reduction image.
     */
    virtual void updateData(uint8_t* data, std::size_t width , std::size_t height, std::size_t level) = 0;
    
    /**
     * Update a two-dimensional texture image in a compressed format
     * @param data Specifies a pointer to the compressed image data in memory.
     * @param width Specifies the width of the texture image.
     * @param height Specifies the height of the texture image.
     * @param dataLen Specifies the totoal size of compressed image in bytes.
     * @param level Specifies the level-of-detail number. Level 0 is the base image level. Level n is the nth mipmap reduction image.
     */
    virtual void updateCompressedData(uint8_t* data, std::size_t width , std::size_t height, std::size_t dataLen, std::size_t level) = 0;
    
    /**
     * Update a two-dimensional texture subimage
     * @param xoffset Specifies a texel offset in the x direction within the texture array.
     * @param yoffset Specifies a texel offset in the y direction within the texture array.
     * @param width Specifies the width of the texture subimage.
     * @param height Specifies the height of the texture subimage.
     * @param level Specifies the level-of-detail number. Level 0 is the base image level. Level n is the nth mipmap reduction image.
     * @param data Specifies a pointer to the image data in memory.
     */
    virtual void updateSubData(std::size_t xoffset, std::size_t yoffset, std::size_t width, std::size_t height, std::size_t level, uint8_t* data) = 0;
    
    /**
     * Update a two-dimensional texture subimage in a compressed format
     * @param xoffset Specifies a texel offset in the x direction within the texture array.
     * @param yoffset Specifies a texel offset in the y direction within the texture array.
     * @param width Specifies the width of the texture subimage.
     * @param height Specifies the height of the texture subimage.
     * @param dataLen Specifies the totoal size of compressed subimage in bytes.
     * @param level Specifies the level-of-detail number. Level 0 is the base image level. Level n is the nth mipmap reduction image.
     * @param data Specifies a pointer to the compressed image data in memory.
     */
    virtual void updateCompressedSubData(std::size_t xoffset, std::size_t yoffset, std::size_t width, std::size_t height, std::size_t dataLen, std::size_t level, uint8_t* data) = 0;

    /**
     * Get texture width.
     * @return Texture width.
     */
    inline std::size_t getWidth() const { return _width; }

    /**
     * Get texture height.
     * @return Texture height.
     */
    inline std::size_t getHeight() const { return _height; }

protected:
    /**
     * @param descriptor Specifies the texture descriptor.
     */
    Texture2DBackend(const TextureDescriptor& descriptor);
};

/**
 * A cubemap texture.
 */
class TextureCubemapBackend : public TextureBackend
{
public:
    /**
     * Update texutre cube data in give slice side.
     * @param side Specifies which slice texture of cube to be update.
     * @param data Specifies a pointer to the image data in memory.
     */
    virtual void updateFaceData(TextureCubeFace side, void *data) = 0;
        
protected:
    /**
     * @param descriptor Specifies the texture descriptor.
     */
    TextureCubemapBackend(const TextureDescriptor& descriptor);
};

//end of _backend group
/// @}
CC_BACKEND_END