Question

在我的程序中，我需要进行屏幕外渲染。为此我使用FBO。为了查看我绘制的图像是否正确用于测试目的，我将其从FBO复制到纹理然后将纹理渲染为四边形。问题是，当我从FBO复制到纹理并渲染它时，图像看起来很暗/得到黑色，但形状是正确的。我已尝试在FBO中使用纹理作为附件并直接渲染（不将其复制到另一个纹理中）并且颜色正确。下面是纹理创建的代码

//initial texture which works when rendered to a quad  
glGenTexturesEXT(3, &textureID[0]);
glBindTextureEXT(GL_TEXTURE_2D, textureID[0]);
glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR_MIPMAP_LINEAR);
glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
glTexParameteri(GL_TEXTURE_2D, GL_GENERATE_MIPMAP, GL_TRUE); 
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA8, 600, 512, 0, GL_RGBA, GL_UNSIGNED_BYTE, 0);
//second one which should be a copy of the above but has tha dark color mentioned
glBindTextureEXT(GL_TEXTURE_2D, textureID[1]);
glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR_MIPMAP_LINEAR);
glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
glTexParameteri(GL_TEXTURE_2D, GL_GENERATE_MIPMAP, GL_TRUE); // automatic mipmap 
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA8, 600, 512, 0, GL_RGBA, GL_UNSIGNED_BYTE, 0);
glBindTextureEXT(GL_TEXTURE_2D, 0);
glFramebufferTexture2DEXT(GL_FRAMEBUFFER_EXT,GL_COLOR_ATTACHMENT0_EXT,GL_TEXTURE_2D,textureID[0],0);
  //Attach depth buffer to FBO
glFramebufferRenderbufferEXT(GL_FRAMEBUFFER_EXT, GL_DEPTH_ATTACHMENT_EXT, GL_RENDERBUFFER_EXT, depth_rb);
st1=glCheckFramebufferStatusEXT(GL_FRAMEBUFFER_EXT);

现在处于渲染功能

glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, fb); //biding FBO
glClear(GL_COLOR_BUFFER_BIT|GL_DEPTH_BUFFER_BIT);
 //render code
unsigned char *pixels= new unsigned char [600*512*4];
glBindFramebufferEXT(GL_FRAMEBUFFER_EXT,0);  //unbiding
glBindTextureEXT(GL_TEXTURE_2D,textureID[1]); //if I change to textureID[0] result is fine
glTexImage2D(GL_TEXTURE_2D,0,GL_RGBA8,600,512,0,GL_RGBA,GL_UNSIGNED_BYTE,pixels);
glBindTextureEXT(GL_TEXTURE_2D,0);
glViewport(0, 0, 600, 512);
glClearColor(1.0,1.0,1.0,1.0);
glClear(GL_COLOR_BUFFER_BIT|GL_DEPTH_BUFFER_BIT);
glBindTextureEXT(GL_TEXTURE_2D, textureID[1]);
  //setting the correct matrixes + render a quad
 //before rendering a quad I set the color with
glColor3f(1.0, 1.0, 1.0);
delete[] pixels;
glutSwapBuffers();

我正在使用过剩设置。在取消FBO并将纹理作为glReadPixels（...）的替代品之后，我尝试了其他函数，例如glGetTexImage2D，但没有成功。

Answer 1

我不理解你的第二个代码片段中对glTexImage2D的这个调用。 pixels将只包含垃圾。你期望它做什么？

纹理在很长一段时间内都是核心OpenGL。它只是glGenTextures而glBindTexture不是...EXT。我还建议使用...ARB版本的FBO功能，或者只使用OpenGL核心帧缓冲支持（以后的OpenGL版本）。

openGL FBO复制到纹理结果为黑/暗图像

1 个答案: