Self-shadowing in Bump and Parallax Occlusion Maps

March 19, 2007 at 3:28 am (Tips & Tricks)

Humus has a great little demo based on Chris Oat’s ambient aperture work . Oat’s stuff was used with terrain lighting in mind, but obviously it can be used on some bump maps also. This is a quick and dirty way to get some self shadowing on your bump mapped/parallax occlusion mapped surface without a bunch of extra texture accesses or aliasing. Oat’s method works by representing the unoccluded part of the hemisphere (the aperture) and the light source by spherical caps ( a direction and arc-length radius) and then computes the intersection of the two. Humus instead calculates the difference between the dot product of the aperture direction and the light direction minus the radius of the aperture. Pretty cool.

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