Well cube mapped shadows gives you the possibility of having projected shadowing with point lights, not just with spot lights. The disadvantage is that it is 6 times slower ebcause it has to be done through 6 directions.

Dave

Quote:Original post by Dave
Well cube mapped shadows gives you the possibility of having projected shadowing with point lights, not just with spot lights. The disadvantage is that it is 6 times slower ebcause it has to be done through 6 directions.

Dave

Well, the shadow _generation_ is about 6x slower. Shadow cubemaps (and derivations of) are basically the only way to make shadow mapping with omnidirectional (aka point) lights work. Perspective shadow maps is for directional lights exclusively (even though the PSM paper suggests that they could be used for omni lights, which I think is an absolute joke. Offscreen omni lights do NOT produce the same results as directional lights).

Has anyone here implemented dual paraboloid shadow mapping? I had a really hard time finding any decent articles about the paraboloid map generation. I finally just got the map generation working correctly, hopefully in the next day or 2 I'll have to time to to finish it all up. I'll post some screens showing quality and speed comparisons between dual paraboloid maps and cube maps for point light shadowing in the next couple days.

Quote:Original post by acid2
Cube maps aren't the only way, Cypher. There's also dual paraboloid shadow maps - thats 2 renders, which is a bit better. Daver, as everyone has says - cube maps give you 360° coverage around a point, which means that a point light can be used.

I hardly feel that DPSMs are practical for scenarios in the real world.

They may be 2 renders, but they're really only useful for either:
-Fairly faraway lights and used as a level of detail control or
-Ridiculously high poly environments (and even in this case, the resulting shadow detail of DPSMs are still absolutely horrible. Plus, what's the point in having 1/3 of the render calls when you need >100x the number of vertices to get correct shadows most of the time?)

The argument of 2 passes just isn't very compelling to me considering the tradeoffs you have to make with regards to resulting detail and extra transformation in the general case scenario. I will totally give you the argument of using them as a LoD system, but even then I'll need some hard results in order to be fully convinced that they're robust enough for even that manner of use.

The main reasoning behind my gripe is the fact that you need to do a curved projection for DPSMs, not a linear one. Plus, you end up getting a ridiculously low quality, as Daver's screenshot of the DPSM demo demonstrates.

Oh, and for the Delphi3d demo, did you check out the wireframe shot of the environment?

Quote:Also "paraboloid mapping ... is more expensive because it requires two texture units or two rendering passes", so if I have only one spare texture unit (0-color map, 1-normal map, 2-height map for parallax mapping, 3-spare), I have to draw all scene twice (this is expensive if I have a huge amount of polygons in the scene).

4 Texture units? I thought most hardware had 8?