Re: [Algorithms] Volumetric lighting question

[Scott B. <Sc...@Ma...>]

This may have been discussed in previous threads but I couldn't find any
info on the subject. Anyway, here goes.

I have concocted a camera dependent / texture based method for simulating
volume lighting which will give very realistic results. Now that is not the
hard part, I'm wondering how in gods name I will try to shade or fog out the
objects passing though the light cone. If I just let the textured cone alpha
blend over the object, this does not accurately depict the true volume
lighting because objects in the cone near the edges might be fully foged
even though there is not enough density to fog it out.

-Have anyone successfully implemented volumetric lighting (and not just a
cone with one alpha value :)  ?

-If so, do you have a way to properly blend objects with it?

-If so, have you been able to incorperate it with your shadowing methods to
produce any kind of shadow bleeding (or whatever you call it)?

And I'm not looking for 200 f/s algorithms here since it's for a 3D software
program and not for a game. :)

Thanks
Scott Bean

----- Original Message -----
From: Charles Bloom <cb...@cb...>
To: <gda...@li...>
Sent: Wednesday, August 02, 2000 9:44 PM
Subject: [Algorithms] fast triangle-segment test *with precomputation*


>
> Ok, so the Moller+Haines triangle-segment test is about
> as good as it gets without any precomputation.  The
> question is, how fast can you get with arbitrary
> precomputation?  For example, I can precompute the
> plane of the triangle, and the three perpendicular
> planes which go through the edges.  Then the intersections
> are all rays that hit the plane of the triangle and
> whose intersection point is inside the three planes.
> (BTW I don't care about computing the barycentric
> coordinates).
>
> Oh, BTW I also don't have the ray normal, so the 'd' used
> in Moller+Haines requires a sqrt() for me to find, so
> that's quite bad.  I think I could probably get the sqrt
> out of there and push the length-squared of the ray through
> the math to help it a bit.
>
> The application here is when I have one triangle and I'm
> about to do thousands of segment-triangle intersection tests
> (actually, lots of bbox-triangle tests, but that requires
> a segment-triangle test).
>
>
> --------------------------------------
> Charles Bloom           www.cbloom.com
>
>
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