cocos2dx学习笔记：CCTexture2D

通过学习CCSpriteFrameCache和CCTextureCache，作者大致了解了底层精灵帧和纹理的管理，这里备份下纹理的内部实现。

构造流程：

CCSpriteFrame需要CCTexture，CCTexture需要CCImage。

CCSprite需要CCTexture和CCSpriteFrame。

CCSpriteFrame较简单，这里就先省略了。
CCSprite需要后续统一分析。

CCImage分析:

分享个大神的blog:

【 http://blog.csdn.net/honghaier/article/details/8032434 】

CCTexture2D代码框架：

CCTexture2D的代码较复杂，涉及到了opengl的东西，作者也晕了，这里就简单的备份下最简单的调用流程。

bool CCTexture2D::initWithImage(CCImage *uiImage)
{
。。。。。
。。。。。
    return initPremultipliedATextureWithImage(uiImage, imageWidth, imageHeight);
}

bool CCTexture2D::initPremultipliedATextureWithImage(CCImage *image, unsigned int width, unsigned int height)
{
。。。。。
。。。。。    
    initWithData(tempData, pixelFormat, width, height, imageSize);
    
    if (tempData != image->getData())
    {
        delete [] tempData;
    }

    m_bHasPremultipliedAlpha = image->isPremultipliedAlpha();
    return true;
}


bool CCTexture2D::initWithData(const void *data, CCTexture2DPixelFormat pixelFormat, unsigned int pixelsWide, unsigned int pixelsHigh, const CCSize& contentSize)
{
    unsigned int bitsPerPixel;
    //Hack: bitsPerPixelForFormat returns wrong number for RGB_888 textures. See function.
    if(pixelFormat == kCCTexture2DPixelFormat_RGB888)
    {
        bitsPerPixel = 24;
    }
    else
    {
        bitsPerPixel = bitsPerPixelForFormat(pixelFormat);
    }

    unsigned int bytesPerRow = pixelsWide * bitsPerPixel / 8;

    if(bytesPerRow % 8 == 0)
    {
        glPixelStorei(GL_UNPACK_ALIGNMENT, 8);
    }
    else if(bytesPerRow % 4 == 0)
    {
        glPixelStorei(GL_UNPACK_ALIGNMENT, 4);
    }
    else if(bytesPerRow % 2 == 0)
    {
        glPixelStorei(GL_UNPACK_ALIGNMENT, 2);
    }
    else
    {
        glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
    }


    glGenTextures(1, &m_uName);
    ccGLBindTexture2D(m_uName);

    glTexParameteri( GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR );
    glTexParameteri( GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR );
    glTexParameteri( GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE );
    glTexParameteri( GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE );

    // Specify OpenGL texture image

    switch(pixelFormat)
    {
    case kCCTexture2DPixelFormat_RGBA8888:
        glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, (GLsizei)pixelsWide, (GLsizei)pixelsHigh, 0, GL_RGBA, GL_UNSIGNED_BYTE, data);
        break;
    case kCCTexture2DPixelFormat_RGB888:
        glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, (GLsizei)pixelsWide, (GLsizei)pixelsHigh, 0, GL_RGB, GL_UNSIGNED_BYTE, data);
        break;
    case kCCTexture2DPixelFormat_RGBA4444:
        glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, (GLsizei)pixelsWide, (GLsizei)pixelsHigh, 0, GL_RGBA, GL_UNSIGNED_SHORT_4_4_4_4, data);
        break;
    case kCCTexture2DPixelFormat_RGB5A1:
        glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, (GLsizei)pixelsWide, (GLsizei)pixelsHigh, 0, GL_RGBA, GL_UNSIGNED_SHORT_5_5_5_1, data);
        break;
    case kCCTexture2DPixelFormat_RGB565:
        glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, (GLsizei)pixelsWide, (GLsizei)pixelsHigh, 0, GL_RGB, GL_UNSIGNED_SHORT_5_6_5, data);
        break;
    case kCCTexture2DPixelFormat_AI88:
        glTexImage2D(GL_TEXTURE_2D, 0, GL_LUMINANCE_ALPHA, (GLsizei)pixelsWide, (GLsizei)pixelsHigh, 0, GL_LUMINANCE_ALPHA, GL_UNSIGNED_BYTE, data);
        break;
    case kCCTexture2DPixelFormat_A8:
        glTexImage2D(GL_TEXTURE_2D, 0, GL_ALPHA, (GLsizei)pixelsWide, (GLsizei)pixelsHigh, 0, GL_ALPHA, GL_UNSIGNED_BYTE, data);
        break;
    case kCCTexture2DPixelFormat_I8:
        glTexImage2D(GL_TEXTURE_2D, 0, GL_LUMINANCE, (GLsizei)pixelsWide, (GLsizei)pixelsHigh, 0, GL_LUMINANCE, GL_UNSIGNED_BYTE, data);
        break;
    default:
        CCAssert(0, "NSInternalInconsistencyException");

    }

    m_tContentSize = contentSize;
    m_uPixelsWide = pixelsWide;
    m_uPixelsHigh = pixelsHigh;
    m_ePixelFormat = pixelFormat;
    m_fMaxS = contentSize.width / (float)(pixelsWide);
    m_fMaxT = contentSize.height / (float)(pixelsHigh);

    m_bHasPremultipliedAlpha = false;
    m_bHasMipmaps = false;

    setShaderProgram(CCShaderCache::sharedShaderCache()->programForKey(kCCShader_PositionTexture));

    return true;
}

CCSprite代码框架：

void CCSprite::setTexture(CCTexture2D *texture)
{
。。。。。
。。。。。
        m_pobTexture = texture;
。。。。。
。。。。。
}

void CCSprite::draw(void)
{
。。。。。
    ccGLBindTexture2D( m_pobTexture->getName() );
    ccGLEnableVertexAttribs( kCCVertexAttribFlag_PosColorTex );
。。。。。
}