Re: [Algorithms] Direct Sunlight Lighting Model

[Zulfiqar M. <zul...@gm...>]

The basic idea is to do rendering in high dynamic range and instead of
writing values outside the range 0 - 1 (since you are using 8-bit format)
you write "scaled" values (each R, G and B channel is scaled with some
factor such that all 3 end up in 0 - 1 range) and the common scaled factor
(also called exponent) is written in the alpha channel (hence the name
RGBE). A little bit more information in. You should be able to find more
information.

http://www.anyhere.com/gward/hdrenc/hdr_encodings.html

I haven't used this format myself and hence don't know of its short comings=
.
One obvious short coming is that you lose the alpha channel. You can also
look into the technique detailed by Humus in the following link

http://www.humus.ca/index.php?page=3D3D

Hope its useful.

-Zul

On 11/21/05, Dan Glastonbury <dan...@gm...> wrote:
>
>
> On 11/20/05, David Whatley <da...@pl...> wrote:
> >
> > You mean use RGBE for the textures? I'm not sure what that would buy me
> > if I'm not using float point buffers.
> >
> > -- David
>
>
> I think he means write RGBE into RGBA of the framebuffer, then do the ton=
e
> mapping on that. Instead of running a luminance filter on the screen to g=
et
> the bright parts, the lighting calculations store what is bright. From my
> understand of the ppt slides, this is how Wreckless worked.
>
> HTH
> DanG
>
> --
> Dan Glastonbury, Dan dot Glastonbury at gmail dot com
> `Pour encourjay lays ortras'
>



--
Regards,
Zulfiqar Inayat Malik.