Shadow algorithm

Hi!

Congrats for your engine.

I just want to know which algorithm do you used for your shadow. It seems that it's shadow mapping but do you use some kind of PCF, variance or exponential shadow mapping?

Keep up the good work!


PS: I have written an potal based engine few years ago but it was with shadow volume... Screenshot and source code on my website

hi
i used to do shadows using shadow volume tech, but they are not supporting none opaque surfaces (such as fences, trees etc) and not to mention translucent materials, they have lots of drawbacks (still, they could be enabled via cvar, and works with shadow mapping as well) so i'm using variance shadow mapping as they are more forgiving than regular shadow mapping.
thanks and bye

I looked at the slides for variance shadow mapping, and I was wondering if you were experiencing any problems with light bleeding. If so, how did you go about fixing them?

Thanks,
Mikfig

hi
i had at first, but now i don't, if you search the bleeding i think you will find but it is not very clear where they are any more.
you can't fix it (unless you do more samples and you end up doing some brute force pcf), but you can reduce it by darkening the penumbra regions.
this could be done by modifying the 'result' (which you compute right now as the shadow occlusion value) so that any values below some threshold will be mapped to 0 and the rest will be mapped to 1, so basically you clamp the result into [0..1] range when the result is less than your threshold.
for more info you can read "gpu gems 3 - summed area variance shadow maps - 8.4.3", thanks to nvidia it is now public

Ok thanks.

Mikfig

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