Depth buffer

From DmWiki

The depth buffer, also called the z-buffer, is one of the buffers that compose a 3D application's frame buffer. The depth buffer stores a measure of the distance from the eye to each visible point of the image.

The main purpose of the depth buffer is to perform hidden surface removal. When the depth test is enabled, each pixel that is about to be rendered is first compared with the pixel already in the frame buffer at that position. The new pixel is drawn only if it passes the depth test; that is, only if its depth value is less than the old one. Thus, objects are only drawn if they are closer to the viewer than the objects already drawn.

To do: talk about precision problems (z-fighting), the near and far planes, rendering opaque vs alpha-blended objects (the latter should be sorted, and have depth-writes turned off)

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