OpenGL帧缓冲-渲染到纹理创建纹理与主要帧缓冲内容

Question

这是更大项目的一部分，基本上，我用以下方式创建带有颜色、深度和模具缓冲区的帧缓冲区：

// Create texture
glGenTextures(1, &m_textureInput);
glBindTexture(GL_TEXTURE_2D, m_textureInput);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA8, getWidth(), getHeight(), 0, GL_BGRA, GL_UNSIGNED_BYTE, 0);
// Create FBOs
glGenFramebuffers(1, &m_fboInput);

glBindFramebuffer(GL_FRAMEBUFFER, m_fboInput);

// Attach texture to it
glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, m_textureInput, 0);

// Render buffer, depth with stencil
glGenRenderbuffers(1, &m_rbDepthStencilInput);
glBindRenderbuffer(GL_RENDERBUFFER, m_rbDepthStencilInput);
glRenderbufferStorage(GL_RENDERBUFFER, GL_DEPTH24_STENCIL8, getWidth(), getHeight());
//Attach depth buffer to FBO
glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_DEPTH_ATTACHMENT, GL_RENDERBUFFER, m_rbDepthStencilInput);
//Also attach as a stencil
glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_STENCIL_ATTACHMENT, GL_RENDERBUFFER, m_rbDepthStencilInput);

status = glCheckFramebufferStatus(GL_FRAMEBUFFER);
if(status != GL_FRAMEBUFFER_COMPLETE)
{
    // Restore current framebuffer
    glBindFramebuffer(GL_FRAMEBUFFER, 0);
    return false;
}

glBindFramebuffer(GL_FRAMEBUFFER, 0);

我用以下方法将其绑定：

glBindFramebuffer(GL_FRAMEBUFFER, m_fboInput);
// render
glBindFramebuffer(GL_FRAMEBUFFER, 0);

当我转储附加的纹理：

glBindTexture(GL_TEXTURE_2D, m_textureInput);
long imageSize = x * y * 4;
unsigned char *data = new unsigned char[imageSize];
glReadPixels(0,0,x,y, GL_BGRA,GL_UNSIGNED_BYTE,data);

我收到主帧缓冲区（0）的内容。

知道我哪里错了吗？先谢谢你。

Answer 1

glReadPixels文档称它从帧缓冲区读取数据。因为您之前将零绑定到它，我猜它将从默认帧缓冲区读取。

您可以绑定帧缓冲区对象，然后使用GL_COLOR\u ATTACHMENT0调用glReadBuffer，然后执行glReadPixels，或者更直接地使用glGetTexImage直接读取纹理。