GBuffer generation

Unlike forward lighting, where we just started rendering the scene with the lights, deferred shading requires the GBuffer to be generated before any light related calculation can take place.

Choosing the structure of the GBuffer is a very important decision. The bare minimum you can get away with is storing depth, base color, normal, specular power, and specular intensity. For this configuration, you will need between three to four render targets.

Storing depth and base color is straight forward. Use a D24S8 render target for the depth and stencil. For base color we will be using an A8R8G8B8 render target as the base color values are usually sampled from 8 bit per-pixel texture. The alpha channel of the color target can be used to store the specular intensity. Storing normals on the other hand is not that simple and requires some planning. To keep this section relatively short, we are only going to cover three storage methods that have been used in popular AAA games.

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