In article <web.3def10d4836ceb7115e7f0160@news.povray.org>,
 "Alex" <ale### [at] alphacit> wrote:

> To simulate illumination from an area light, POVRay would have to perform
> the whole illumination calculation for each of the shadow rays used to test
> for occlusion.
> 
> This would mean a (probably) large increase in rendering time and complexity
> of the code, altough a crude hack coud involve entirely special casing area
> ligths.

One possible alternative I can think of would be to use a separate 
resolution for the illumination calculation and shadow calculation. In 
most cases, you only need lots of samples to get smooth shadows, you 
should be able to get away with much less for the illumination.

Another odd idea is this: the lighting calculations depend on the angle 
of the normal to a point (a simplification), the center of the light 
source. Instead, use the angle to either a disk, line, or rectangle, if 
the normal points inside the light the angle is 0. No sampling, so it 
would be faster than shooting rays though slower than a point 
approximation. It won't work properly in partial shadow, but should be 
closer to reality than the point approximation.

Ideally, you would be able to choose which you wanted: true area light, 
point, line, disk, or rectangle approximations.

-- 
Christopher James Huff <cja### [at] earthlinknet>
http://home.earthlink.net/~cjameshuff/
POV-Ray TAG: chr### [at] tagpovrayorg
http://tag.povray.org/

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