OpenGL Programming Guide: The Official Guide to Learning OpenGL, Version 4.3, Eighth Edition

Advanced

One feature of using framebuffer objects with multiple renderbuffer (or textures, as described in Chapter 6, “Textures”) is the ability to write to multiple buffers from a fragment shader simultaneously, often called MRT (for multiple-render target) rendering. This is mostly a performance optimization, saving processing the same list of vertices multiple times and rasterizing the same primitives multiple times.

While this technique is used often in GPGPU, it can also be used when generating geometry and other information (like textures or normal map) which is written to different buffers during the same rendering pass. Enabling this technique requires setting up a framebuffer object with multiple color (and potentially depth and stencil) ...