In article <389ff3c1@news.povray.org>, "Bob Hughes" 
<per### [at] aolcom?subject=PoV-News:> wrote:

> I can't really ask the right questions since I don't know how you're 
> doing this, and trying to explain it to me would perhaps be futile.

Well, I will try anyway.


> All I'm wondering though is if this "texture" were more a pattern 
> type than a sampling of a surface that it might be more linear I 
> guess would be the term. I'm just dreaming this up in a way that 
> would mean the texture would follow the contours of any object like a 
> uv map or something and without the sampling sort of stuff which 
> obviously is hit and miss to deduce where it goes.

It is a pattern, just like bozo, crackle, or wrinkles. It is calculated 
a bit differently from most, but is used in the same way any other 
pattern is used. It depends on the object, like slope.
At each point on the surface of the object, several rays are shot in all 
directions that don't go "down" relative to the normal at that point. 
They spread out in a half-sphere with the flat portion centered over the 
point. The percentage of the rays that hit is returned.

Another way to think of it is as a pattern which returns the amount of 
visible "sky". If the point is on the side of a box sitting on a plane, 
and very close to the ground plane, about half of it's "sky" will be 
covered by the plane. On a color_map ranging from black at 0 to white at 
1, it would be 50% gray. If the point is on the surface of a sphere, the 
whole sky will be visible, and the result will be white. If it is close 
to the point of contact between two spheres, only a narrow strip of sky 
will be visible, and you will get a dark gray.

It doesn't have anything to do with UV mapping, and I don't see how UV 
mapping could be applied to this problem, unless you mean by using an 
image_map or material_map to specify the areas with "patina".


> Plain and simple I can't understand the dynamics of your work anyhow, 
> so excuse me if I go way off track trying to figure it out.  What it 
> causes me to think is that if a object surface can be found and 
> mimicked in a changed way like this does do then it just seems then 
> that the texture could follow that surface and be applied as though a 
> typical patterned texture is with the usual way.

Are you thinking of a possible way to use this kind of thing to control 
UV mapping? So that the map is adjusted over the contours of the surface 
of the object?


> I think I see how you might not be following what I say, it reads to 
> me like round in circles.

I think I am starting to understand a little, although I am still unsure 
what exactly you mean.

-- 
Chris Huff
e-mail: chr### [at] yahoocom
Web page: http://chrishuff.dhs.org/

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