FBO Creating: Why always incomplete read buffer?

OpenGL OpenGL: Advanced Coding
1

The code come from Martin Eisemann’s sample project “Floating Texture”,
everyone can use it under GPL: Floating Textures download | SourceForge.net

I got VS 2010 as my Compiler&Linker, the external libraries include GLEW GLUT and OpenCV

Here is the problem:

  1. There are 3 FBO to be created:


  mInputTexID = createFBOTexture(width, height);
  mInputFBO = createFBO(mInputTexID);

  mBGTexID = createFBOTexture(width, height);
  mBGRBID  = createFBORenderbuffer(width, height);
  mBGFBO   = createFBO(mBGTexID, mBGRBID);

  mVisTexID = createFBOTexture(mShadowRes, mShadowRes, GL_TEXTURE_2D, GL_DEPTH_COMPONENT, GL_DEPTH_COMPONENT,    
                                             GL_FLOAT,  GL_LINEAR, GL_LINEAR, GL_CLAMP, GL_CLAMP);
  const GLenum attachment[] = {GL_DEPTH_ATTACHMENT_EXT};
  mVisFBO = createFBO(&mVisTexID, attachment, 1);

First two FBO work fine while the last one–mVisFBO can not be created, I get GL_FRAMEBUFFER_INCOMPLETE_READ_BUFFER_EXT when glCheckFramebufferStatusEXT (GL_FRAMEBUFFER_EXT) is called.

Here are the routines:



 GLuint createFBOTexture(const int width, const int height, 
			const GLenum target = GL_TEXTURE_2D, 
			const GLenum internalFormat = GL_RGBA16F_ARB,
			const GLenum format = GL_RGBA, 
			const GLenum type = GL_FLOAT, 
			const GLenum mag_filter = GL_LINEAR, 
			const GLenum min_filter = GL_LINEAR,
			const GLenum wrap_s = GL_CLAMP, 
			const GLenum wrap_t = GL_CLAMP)
{
  // generate texture id //
  GLuint texID;
  glGenTextures(1, &texID);

  // set parameters //
  glBindTexture(GL_TEXTURE_2D, texID);
  glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, wrap_s);
  glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, wrap_t);

  glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, mag_filter);
  glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, min_filter);

  glTexImage2D(target, 0, internalFormat, width, height, 0, format, type, 0);

  return texID;
}


GLuint createFBORenderbuffer(const int width, const int height, 
			     const GLenum internalFormat = GL_DEPTH_COMPONENT24)
{
  GLuint rbID;
  glGenRenderbuffersEXT(1, &rbID);
  glBindRenderbufferEXT(GL_RENDERBUFFER_EXT, rbID);
  glRenderbufferStorageEXT(GL_RENDERBUFFER_EXT, internalFormat, width, height);

  return rbID;
}

GLuint createFBO(const GLuint texID = 0, const GLuint renderbufferID = 0)
{
  const int    numTexs = (texID == 0) ? 0 : 1;  
  const GLenum texAttachments[] = {GL_COLOR_ATTACHMENT0_EXT};
  const GLenum attachment[] = {GL_DEPTH_ATTACHMENT_EXT};
  const int    numrb = (renderbufferID != 0) ? 1 : 0;
  const GLenum db[] = {GL_COLOR_ATTACHMENT0_EXT};

  return createFBO(&texID, texAttachments, numTexs, 
		   &renderbufferID, attachment, numrb,
		   db, numTexs);
}

GLuint createFBO(const GLuint texIDs[],
		 const GLenum texAttachments[],
		 const int numTexs, 
		 const GLuint rbIDs[] = NULL,
		 const GLenum rbAttachments[] = NULL,
		 const int numrb = 0,
		 const GLenum db[] = NULL,
		 const int numdb = 0)
{
  GLuint fboID = 0;

  // generate framebuffer //
  glGenFramebuffersEXT(1, &fboID);
  glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, fboID);


  // attach texture to frambuffer //
    checkMaxDrawBuffers(numTexs);

    for(int i=0; i<numTexs; ++i){
    glFramebufferTexture2DEXT(GL_FRAMEBUFFER_EXT, 
			      texAttachments[i],
			      GL_TEXTURE_2D, texIDs[i], 0);
     }    

  // attach renderbuffer to framebuffer //
    for(int i=0; i<numrb; ++i){
    glFramebufferRenderbufferEXT(GL_FRAMEBUFFER_EXT, rbAttachments[i], 
				 GL_RENDERBUFFER_EXT, rbIDs[i]);     
     } 

  // set drawbuffers //
  switch(numdb){
  case 0:
    glDrawBuffer(GL_NONE);
    break;
  case 1:
    glDrawBuffer(db[0]);
    break;
  default:
    glDrawBuffers(numdb, db);
    break;
  }

  // set parameters //
  glEnable(GL_DEPTH_TEST);
  glDepthFunc(GL_LEQUAL);

  // check for errors //
  GLenum status = glCheckFramebufferStatusEXT (GL_FRAMEBUFFER_EXT);

  //Here  I got the Error :GL_FRAMEBUFFER_INCOMPLETE_READ_BUFFER_EXT

  return fboID;
}

Thanks for any tips&help!!!

2

Please don’t make your text this big!!! Just use the regular font size!!!

See? Isn’t that much better?

As for your question, you didn’t put a color image into the FBO. Your code explicitly checks this and correctly calls glDrawBuffer(GL_NONE). What you didn’t do is call glReadBuffer(GL_NONE), which is why you’re getting INCOMPLETE_READ_BUFFER.

With the exception of UNSUPPORTED, the incomplete messages are generally quite specific as to what has gone wrong.

3

Thanks for your help, Alfonse Reinheart! Both on the FBO and font size issues :slight_smile:

For anyone stuck in similiar problems :

I add glReadBuffer(GL_NONE) when there are no draw buffers



  // set drawbuffers //
  switch(numdb){
  case 0:
    glDrawBuffer(GL_NONE);
    glReadBuffer(GL_NONE);
    break;
  case 1:
    glDrawBuffer(db[0]);
    break;
  default:
    glDrawBuffers(numdb, db);
    break;
  }