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Shadows from point lights


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#1 SamiHuutoniemi   Members   -  Reputation: 259

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Posted 10 December 2012 - 09:31 AM

Hello!

I'm doing some shadowmapping and was wondering about how it is done with point lights (instead of spot lights). Since you don't really have a light direction, how do decide what the shadowmap should cover?

Anybody have experience in this field?

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#2 Radikalizm   Crossbones+   -  Reputation: 2836

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Posted 10 December 2012 - 09:55 AM

You'll have to render multiple shadow maps for a point light.
One of the easiest and probably the most common way to do this is to render 6 shadow maps forming a cube.
Another popular approach is to use dual paraboloid shadow maps which only require 2 shadow maps, but which suffer from some precision issues.

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#3 SamiHuutoniemi   Members   -  Reputation: 259

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Posted 10 December 2012 - 10:01 AM

The cube version sounds very much easier. Does it still use perspective projection?

#4 MrOMGWTF   Members   -  Reputation: 433

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Posted 10 December 2012 - 10:02 AM

The cube version sounds very much easier. Does it still use perspective projection?


You always use ortographic projection afaik.

#5 Radikalizm   Crossbones+   -  Reputation: 2836

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Posted 10 December 2012 - 10:04 AM

It's pretty much the same as rendering 6 spot light shadow maps with a field of view of 90°, so yes it still uses a perspective projection.

EDIT:


The cube version sounds very much easier. Does it still use perspective projection?


You always use ortographic projection afaik.


Orthographic projections are for directional shadow maps.

Edited by Radikalizm, 10 December 2012 - 10:05 AM.

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#6 SamiHuutoniemi   Members   -  Reputation: 259

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Posted 10 December 2012 - 10:06 AM

Ok, thanks! Will look into this!




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