framebuffer和在opengl中使用着色器

Question

我對幀緩衝區有點困惑。我想要做的是使用附加了多個紋理的幀緩衝區，填充每個紋理，然後使用着色器組合（混合）所有紋理以創建新的輸出。聽起來很容易？是的，這也是我的想法，但我不明白。

如何將當前綁定的紋理傳遞給着色器？

Answer 1

您需要將紋理放入特定插槽，然後使用採樣器從中讀取紋理。在您的應用程序：

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使用這一點，所以在你的着色器訪問更加質感。