Get the maximum number of colored framebuffer attachments?

There are two values ​​that can potentially limit the number of attachments you can use:

• GL_MAX_COLOR_ATTACHMENTS
  
  indicates how many color anchor points the FBO has. In other words, this corresponds to the maximum value n
  
  that you can use when specifying anchor points with GL_COLOR_ATTACHMENTn
  
  . This will limit the number of color textures / renders to simultaneously attach to the FBO. You can get this limit with:

  GLint maxAttach = 0;
  glGetIntegerv(GL_MAX_COLOR_ATTACHMENTS, &maxAttach);
  
        
  
          
          
          
        
  
      

• GL_MAX_DRAW_BUFFERS
  
  indicates how many buffers you can use at the same time. This is the maximum number of buffers you can go to glDrawBuffers()
  
  , as well as the maximum number of outputs allowed in fragment shaders. You can get this limit with:

  GLint maxDrawBuf = 0;
  glGetIntegerv(GL_MAX_DRAW_BUFFERS, &maxDrawBuf);
  
        
  
          
          
          
        
  
      

These two values ​​do not need to be the same. Thus, it is possible that you can have a certain amount of attachments, but you cannot attract all of them at the same time.

The minimum value for both of these limits is 8 in OpenGL 3.x and up, up to the current 4.5 spec.