framebuffer和在opengl中使用着色器

Question

我对帧缓冲区有点困惑。我想要做的是使用附加了多个纹理的帧缓冲区，填充每个纹理，然后使用着色器组合（混合）所有纹理以创建新的输出。听起来很容易？是的，这也是我的想法，但我不明白。

如何将当前绑定的纹理传递给着色器？

Answer 1

您需要将纹理放入特定插槽，然后使用采样器从中读取纹理。在您的应用程序：

GLuint frameBuffer; 
glGenFramebuffersEXT(1, &frameBuffer); //Create a frame buffer 
glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, frameBuffer); //Bind it so we draw to it 
glFramebufferTexture2DEXT(GL_FRAMEBUFFER_EXT, GL_COLOR_ATTACHMENT0_EXT, GL_TEXTURE_2D, yourTexture, 0); //Attach yourTexture so drawing goes into it 

//Draw here and it'll go into yourTexture. 

glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, 0); //Unbind the framebuffer so that you can draw normally again 

//Here we put the texture in slot 1. 
glActiveTexture(GL_TEXTURE1); 
glBindTexture(GL_TEXTURE_2D, yourTexture); 
glActiveTexture(GL_TEXTURE0); //Don't forget to go back to GL_TEXTURE0 if you're going to do more drawing later 

//Now we tell your shader where to look. 
GLint var = glGetUniformLocationARB(yourShaderProgram, "yourSampler"); 
glUniform1i(var, 1); //We use 1 here because we used GL_TEXTURE1 to bind our texture 

而在你的片段着色器：

uniform sampler2D yourSampler; 

void main() 
{ 
    gl_FragColor = texture2D(yourSampler, whateverCoordinatesYouWant); 
} 

您可以GL_TEXTURE2使用这一点，所以在你的着色器访问更加质感。