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ehmdjii

reasonable size for shadow-map

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hello, i am targeting rather low-end hardware, so i was wondering what is a reasonable size for a shadowmap (FBO) that still performs smoothly on graphics cards like GeForce2 and Intel GMA 800s also, does anyone know of a list of graphic cards series that support the framebufferobject extension? thanks!

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FBOs are not supported to my knowledge on GF2/3 hardware and may include GF4 also? So you will have to use glTexCopyImage2D() and that will be screen size limited. So I would use 512x512 for a default size then, and increase it based on the screen size.

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Quote:
Original post by MARS_999
FBOs are not supported to my knowledge on GF2/3 hardware and may include GF4 also? So you will have to use glTexCopyImage2D() and that will be screen size limited. So I would use 512x512 for a default size then, and increase it based on the screen size.


That is correct. They are not supported on the GF4 MX series, however they are on the Ti series.

pbuffers are supported though. I've never used them but apparently they're pretty icky, however.

So yeah, you'll be limited to something like 512x256, if rendering at 640x480 resolution (512x512 for 800x600, etc)

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Quote:
Original post by mightypigeon
pbuffers are supported though. I've never used them but apparently they're pretty icky, however.
Eyaargh!
I had the unfortunate idea to try using them... Rendering a 64x64 pbuffer shadowmap (GF4 Ti4600) took more time than rendering the rest of the whole frame (1024x768x32bpp).
Driver somehow improved since then. Last time I tried them out was on 6600GT. They were much better: rendering a 512x512 buffer was pretty like rendering a Doom3 frame (about 40fps).

In general, if retro-compatibility is your concern, then shadowmapping is out of reach (there's a reason if Doom3 technology didn't use shadowmaps in the beginning).
Targeting so old stuff makes sense for integrated graphics and such but they proven to be a whole different world from discrete cards.
It doesn't make much sense to target so old discrete cards... most GF2 will probably be in the junkyard by now.
If you still want to go for them remember you'll be faced with plenty of weird issues... old drivers for first (don't count on VBO and not even on autoMipmapGen) then consider those PCs will probably have some problems as well... Good luck!

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thank you very much for the valuable information!

so, i shouldnt use the framebuffer extension when targeting older hardware...

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