Lately disscussed with a friend about penumbra shadows. I found a paper about this theme which used a edge detection filter to achive penumbra shadows, so I wrote a edge-detection filter in rendermonkey. Basically it looks if the difference between 5 pixels, which are ordered in a cross, are to high, then it is a edge pixel.

Needed Extensions:

• none

Download:

edge-filter.rfx (RenderMonkey 1.80)