In article <oig79v0ogstjpldan48el31la2a9f1ulp3@4ax.com>,
 ABX <abx### [at] abxartpl> wrote:

> Arent't near locations only highlighted in
> http://news.povray.org/povray.binaries.images/22100/150459/proximity.jpg ?

Yes, but the "highlighting" is not a function of nearness, but of the 
amount of nearby space occupied by the object. The two often correlate, 
and can be used for some of the same purposes, but they aren't the same 
thing.


> > The proximity pattern uses the minimum or average distance to the 
> > surface of the object, in other words, nearness.
> 
> I know algorithm of your pattern from old MegaPOV but is there any 
> other source where such implementation of "proximity" exist ? Is 
> "distance" the only appearance of "proximity"? Can't blur with 
> specified amount/radius builded over monochrome pattern also mean 
> proximity with clipped values ?

Distance is what the word "proximity" means! It doesn't mean anything 
like blur.


> > You can have proximity to flat objects like triangles, or even 
> > single points, but they have no volume and will be invisible to 
> > your function.
> 
> IIRC I never stated I made 3D pattern.

And I didn't say anything about 3D or 2D. I'm talking about the 
properties of solid vs. patch objects.


> In further changes (which was 
> never released) of this macro I internally used f_r() function which 
> simply returned distance.

Distance to < 0, 0, 0>. This is the proximity function for a single 
point, and abs(f_r(x, y, z)-r) for a sphere. If you did something like 
one of those, it was a proximity function, but a convolution blur isn't. 
The only way I can think of to apply this to a convolution blur is to 
use it to weight the samples.
There are two ways to compute proximity: define a proximity function for 
the object, or compute it from points *on* the object's surface. The 
insideness function is not sufficient...well, you *could* use it to 
search for points very near the surface, but calculation would take 
forever, and it would be nearly impossible to implement in POV functions.


> And that's why I refer to it as "proximity/blur". I will try to 
> remember to use this always in that form in that future.

But it has nothing to do with proximity.

-- 
Christopher James Huff <cja### [at] earthlinknet>
http://home.earthlink.net/~cjameshuff/
POV-Ray TAG: chr### [at] tagpovrayorg
http://tag.povray.org/

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