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Gorg
08-17-2002, 08:39 PM
I am trying to figure out how to do very bright lights. I read that Doom3 and quake3 does some sort of pre-modulation and post-scaling.

This seems to point to the chapter 5 of Jim Blinn's Dirty Pixels, but I cannot seem to find a way to implement the scheme aside from doing the transformation from 16 bits to 8 bits on the CPU.



[This message has been edited by Gorg (edited 08-17-2002).]

V-man
08-19-2002, 03:27 PM
What do you mean by very bright lights?

If you are talking about light maps, then all you have to do is control their brightness in photoshop, else you use combiners.

Lights look fine to me in Doom3 and q3.

V-man

SirKnight
08-19-2002, 04:53 PM
He means by being able to get more intensity out of lights. Like what you see in those high dynamic range demos w/ the radeon 9700.

Quake 3 hacks this a bit to get a greater range. From 0 to 2 I think. Carmack said something about this in a plan, or was it an interview, well whatever. Really though, inorder to get lights that can be bright like you want and have a large range of intensity is to wait for the next gen hardware (9700 & NV30) with their floating point color for high dynamic range. Now you can hack it like Carmack did but it's still not that great (and no were near the quality and range that the next gen hardware will give you). Actually i'm not even 100% on how to do that. I seem to remember a discussion on here that talked a bit about this.

-SirKnight

SirKnight
08-19-2002, 05:51 PM
Actually you know what. Why dont you try this link out and see if it helps any.
http://developer.nvidia.com/view.asp?IO=gdc_hdr

-SirKnight

jwatte
08-19-2002, 05:56 PM
Map 128 to "full bright" and 255 to "over bright" and set the gamma on the card to make 128 the brightest.

Gorg
08-19-2002, 07:49 PM
Thank you guys!

V-man
08-20-2002, 05:55 AM
I didn't know that q3 did that. It looks like a basic game with great usage of multitexturing and a whole lot of animation of all sorts.

I don't think that the high dynamic range trick is a good idea for games. It will make some parts look to dark, almost black since our eyes are not sensitive to low brighness colors. Its better for CGI.

or I would have to a game using it to see if I like it http://www.opengl.org/discussion_boards/ubb/smile.gif

V-man