如何渲染到OpenGL Cubemap纹理的一面

Question

我正在制作一个立方体贴图渲染目标类。我已经有一个2D的作品了。但是对于这个立方体贴图渲染目标类，我希望能够根据需要渲染到特定的面孔。也许我想在“ X +”面上渲染圆，但在“ Y +”面上渲染三角形。

这是我班的样子

class CRenderTarget 
{
private:
    //frame buffer to render on
    unsigned  m_uifboHandle;

    //depth stencil 
    unsigned  m_uiDepthStencilHandle;

    //the texture we will render on
    unsigned  m_uiTextureHandle;

public:
    CCubeRenderTarget( void );

    ~CCubeRenderTarget( void );

    void Create( unsigned uiHeightWidth = 512,
             int iInternalFormat = 0x1908 ); //GL_RGBA

    void Bind( void );

    void UnBind( void );
}

这就是我的create函数的样子

void Create( unsigned uiHeightWidth, int iInternalFormat )
{
        //generate our variables
    glGenFramebuffers(1, &m_uifboHandle);
    glGenRenderbuffers(1, &m_uiDepthStencilHandle);
    glGenTextures(1, &m_uiTextureHandle);

    // Initialize FBO
    glBindFramebuffer( GL_FRAMEBUFFER, m_uifboHandle);

    glBindTexture( GL_TEXTURE_CUBE_MAP, m_uiTextureHandle);

    // Pre-allocate the correct sized cube map
    glTexImage2D(GL_TEXTURE_CUBE_MAP_POSITIVE_Z, 0, iInternalFormat, uiHeightWidth, uiHeightWidth, 0, GL_RGB, GL_UNSIGNED_BYTE, NULL);
    glTexImage2D(GL_TEXTURE_CUBE_MAP_NEGATIVE_Z, 0, iInternalFormat, uiHeightWidth, uiHeightWidth, 0, GL_RGB, GL_UNSIGNED_BYTE, NULL);
    glTexImage2D(GL_TEXTURE_CUBE_MAP_POSITIVE_X, 0, iInternalFormat, uiHeightWidth, uiHeightWidth, 0, GL_RGB, GL_UNSIGNED_BYTE, NULL);
    glTexImage2D(GL_TEXTURE_CUBE_MAP_NEGATIVE_X, 0, iInternalFormat, uiHeightWidth, uiHeightWidth, 0, GL_RGB, GL_UNSIGNED_BYTE, NULL);
    glTexImage2D(GL_TEXTURE_CUBE_MAP_POSITIVE_Y, 0, iInternalFormat, uiHeightWidth, uiHeightWidth, 0, GL_RGB, GL_UNSIGNED_BYTE, NULL);
    glTexImage2D(GL_TEXTURE_CUBE_MAP_NEGATIVE_Y, 0, iInternalFormat, uiHeightWidth, uiHeightWidth, 0, GL_RGB, GL_UNSIGNED_BYTE, NULL);

    glTexParameteri(GL_TEXTURE_CUBE_MAP, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
    glTexParameteri(GL_TEXTURE_CUBE_MAP, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
    glTexParameteri(GL_TEXTURE_CUBE_MAP, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
    glTexParameteri(GL_TEXTURE_CUBE_MAP, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
    glTexParameteri(GL_TEXTURE_CUBE_MAP, GL_TEXTURE_WRAP_R, GL_CLAMP_TO_EDGE);

    // Must attach texture to framebuffer. Has Stencil and depth
    glBindRenderbuffer(GL_RENDERBUFFER, m_uiDepthStencilHandle);
    glRenderbufferStorage(GL_RENDERBUFFER, /*GL_DEPTH_STENCIL*/GL_DEPTH24_STENCIL8, uiHeightWidth, uiHeightWidth );
    glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_DEPTH_ATTACHMENT, GL_RENDERBUFFER, m_uiDepthStencilHandle);
    glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_STENCIL_ATTACHMENT, GL_RENDERBUFFER, m_uiDepthStencilHandle);

    glBindFramebuffer(GL_FRAMEBUFFER, 0);
}

这就是我的绑定函数的样子

void Bind( void )
{
    glBindFramebuffer( GL_FRAMEBUFFER, m_uifboHandle );
}

//这就是我的unbind函数的样子

void Unbind( void )
{
    glBindFramebuffer( GL_FRAMEBUFFER, 0 );
}

过去一周，我做了很多研究。我似乎无法找到一种方法，可以只绑定我的多维数据集映射的一张脸，而不是绑定整个多维数据集映射。这是我的总体目标。我知道在DirectX中，您可以只抓住6个面并手动处理它们，但是我如何在openGL立方体贴图上手动处理每个面呢？

Answer 1

绑定了帧缓冲区后，您需要指定应该定位的纹理级别。应该是这样的：

glBindFramebuffer( GL_FRAMEBUFFER, m_uifboHandle );
glFramebufferTexture2D( GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_CUBE_MAP_POSITIVE_X, m_uiTextureHandle, 0);