OpenGL Programming Guide

Chapter 10The Framebuffer

Buffers and Their Uses

An OpenGL system can manipulate the following buffers:

• Color buffers: front-left, front-right, back-left, back-right, and any number of auxiliary color buffers
  
  

• Depth buffer
  
  

• Stencil buffer
  
  

• Accumulation buffer

Your particular OpenGL implementation determines which buffers are available and how many bits per pixel each holds. Additionally, you can have multiple visuals, or window types, that have different buffers available. At a minimum, you're guaranteed to have one color buffer for use in RGBA mode with associated stencil, depth, and accumulation buffers that have color components of nonzero size, and one color buffer for use in color-index mode with associated depth and stencil buffers. Table 10-1 lists the parameters to use with glGetIntegerv() to query your OpenGL system about per-pixel buffer storage for a particular visual. If you're using the X Window System, you'll probably want to use glXGetConfig() to query your visuals; see Appendix D and the OpenGL Reference Manual for more information about this routine.

Table 10-1 : Query Parameters for Per-Pixel Buffer Storage

Parameter	Meaning
GL_RED_BITS, GL_GREEN_BITS, GL_BLUE_BITS, GL_ALPHA_BITS	Number of bits per R, G, B, or A component in the color buffers
GL_DEPTH_BITS	Number of bits per pixel in the depth buffer
GL_STENCIL_BITS	Number of bits per pixel in the stencil buffer
GL_ACCUM_RED_BITS, GL_ACCUM_GREEN_BITS, GL_ACCUM_BLUE_BITS, GL_ACCUM_ALPHA_BITS	Number of bits per R, G, B, or A component in the accumulation buffer

Color Buffers
Clearing Buffers
Selecting Color Buffers for Writing
Masking Buffers

OpenGL Programming Guide