POV-Ray : Newsgroups : povray.general : Cone of light : Re: Cone of light Server Time
7 Aug 2024 03:17:43 EDT (-0400)
  Re: Cone of light  
From: Christopher James Huff
Date: 14 Jan 2002 22:08:58
Message: <chrishuff-6CCAF5.22094314012002@netplex.aussie.org>
In article <k3q64usckpm6tm8lc135hcojuglr284i49@4ax.com>,
 Peter Popov <pet### [at] vipbg> wrote:

> You can easily see that if you place your cone so that the vertex is
> at the location of the light source, be it point or spot, the rays of
> light will be either inside the cone, outside the cone or coincident
> with it. The latter is highly unlikely due to numeric inaccuracies
> inherent to the way computers treat floating point numbers, so in
> practice no way will intersect the cone's surface (except the base),
> and that's what really counts in raytracing.

However, this looks like just the type of situation where a point will 
sometimes be lit, sometimes in shadow, etc. exactly because of precision 
errors, though it probably wouldn't cause any difference in illumination 
because of the steep angle. This is why I recommended using ambient only 
and a diffuse of 0. Similarly, the specular highlights will only show up 
if the cone is hit by another light, and I can't think of any reason 
they would be desireable.

-- 
 -- 
Christopher James Huff <chr### [at] maccom>


Post a reply to this message

Copyright 2003-2023 Persistence of Vision Raytracer Pty. Ltd.