Tim Nikias nous apporta ses lumieres en ce 2005-05-20 20:52:
>>Is there a way in POV-Ray to make projections from a point? Maybe it's
>>possible to design something that does this manually ...
> 
> 
> What you're describing is what POV-Ray is doing. You define an array of
> lights in arealights. It begins with the first four in the corners: if all
> are shadowed, the pixel is considered in shadow. The adaptive step sets a
> minimum limit of corners to check (note that adaptive 1 will check 9 points:
> four in the corners, then every between the corners). Look it up in the
> documentation, I'm a little lazy to write it all out. :-P
> 
> Basically, you can use an enormous array of lights, and POV-Ray will only
> use the amount needed until it calculates to be certain that a given
> threshold of accuracy is reached. Still, it slows down the rendering
> process, as this arealight will be used for the entire scene.
> 
> Note though that with arealights, only the shadows will receive softening,
> specular highlights are still treated like from a pointlight.
> 
> Regards,
> Tim
> 
I've done some observations about the adaptive in an area_light:
Adaptive_value	Smalest_aray_that_POV-Ray_try_to_use
	0	2*2
	1	3*3
	2	5*5
	3	9*9
	4	17*17
	5	33*33
	6	65*65
The formula I came about is: 2^(adaptive value)+1
If two of those points are different, then you try to find a point from the aray that
the closest to 
the mid distance between the two perceding points. (the default aray of 4*4 is bad in
this case)

Alain

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