OpenGL 片段着色器未写入 fbo 颜色缓冲区

Question

我在从片段着色器写入 FBO 中的颜色缓冲区时遇到问题。这个想法是绘制到这个纹理，然后把这个纹理绘制成一个四边形。 问题是，着色器在绘制到默认窗口缓冲区时起作用，因为如果我删除 FBO，则会显示场景。并且四边形的纹理也有效，我用导入的纹理尝试了它，它显示了。我得到的只是黑屏。可能出了什么问题？ :(

创建 FBO 的代码：

glGenFramebuffers(1, &fbo);
glBindFramebuffer(GL_FRAMEBUFFER, fbo);

glGenRenderbuffers(1, &depthbuff); //Add a depth renderbuffer for depth testing
glBindRenderbuffer(GL_RENDERBUFFER, depthbuff);
glRenderbufferStorage(GL_RENDERBUFFER, GL_DEPTH_COMPONENT, width, height);
glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_DEPTH_ATTACHMENT, GL_RENDERBUFFER, depthbuff);

//Add the buffer to be drawn to and the buffer for the picking information
glGenTextures(1, &drawbuff);
glBindTexture(GL_TEXTURE_2D, drawbuff);
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA8, width, height, 0, GL_RGBA, GL_UNSIGNED_BYTE, 0);
glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, drawbuff, 0);

glGenTextures(1, &pickingbuff);
glBindTexture(GL_TEXTURE_2D, pickingbuff);
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA8, width, height, 0, GL_RGBA, GL_UNSIGNED_BYTE, 0);
glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT1, GL_TEXTURE_2D, pickingbuff, 0);

渲染代码：

glBindFramebuffer(GL_FRAMEBUFFER, fbo);
GLenum buffers[] = { GL_COLOR_ATTACHMENT0, GL_COLOR_ATTACHMENT1 };
glDrawBuffers(2, buffers);

shader->bind(); //If the three lines above are removed, it draws correctly to the window
drawStuff();

四边形代码：

quadshader->bind();
glEnable(GL_TEXTURE_2D);
int drawTexID = quadshader->uniformLocation("drawTex");

glActiveTexture(GL_TEXTURE0);
//glBindTexture(GL_TEXTURE_2D, anotherTexture); //This works. A texture imported from a TGA
glBindTexture(GL_TEXTURE_2D, drawbuff);
glUniform1i(drawTexID, 0);

drawQuad();

最后，碎片着色器，我只是将它设置为将所有内容绘制为纯色：

void main(void) {
    gl_FragData[0] = vec4(1.0, 1.0, 0.0, 1.0);
    gl_FragData[1] = vec4(0.0, 1.0, 1.0, 1.0);
}

编辑：如果有任何帮助，整个事情都在 Qt GLWidget 中。

Answer 1

您是否注意确保您的纹理不会同时绑定到采样器 (glBindTexture) 和帧缓冲区？如果您尝试在纹理绑定到活动采样器时写入纹理，或者如果您尝试在纹理附加到活动帧缓冲区时对其进行采样，我认为该行为是错误或未定义。