Ron Parker wrote:
> 
> On Wed, 02 Feb 2000 02:45:14 -0800, Ken wrote:
> >As Ron mentioned I brought this up a couple of months ago in the unofficial
> >patches group. An excellent paper on patina's can be found at -
> >
> >http://graphics.lcs.mit.edu/~dorsey/papers/patina/
> 
> I didn't say anything!  But we did discuss it a while ago...

My mistake and my apology for mistaking you as someone else.

Will you ever forgive me ?

-- 
Ken Tyler -  1300+ Povray, Graphics, 3D Rendering, and Raytracing Links:
http://home.pacbell.net/tylereng/index.html http://www.povray.org/links/

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On Wed, 02 Feb 2000 07:28:15 -0800, Ken wrote:
>
>
>Ron Parker wrote:
>> 
>> On Wed, 02 Feb 2000 02:45:14 -0800, Ken wrote:
>> >As Ron mentioned I brought this up a couple of months ago in the unofficial
>> >patches group. An excellent paper on patina's can be found at -
>> >
>> >http://graphics.lcs.mit.edu/~dorsey/papers/patina/
>> 
>> I didn't say anything!  But we did discuss it a while ago...
>
>My mistake and my apology for mistaking you as someone else.
>
>Will you ever forgive me ?

It's forgotten already.

-- 
These are my opinions.  I do NOT speak for the POV-Team.
The superpatch: http://www2.fwi.com/~parkerr/superpatch/
My other stuff: http://www2.fwi.com/~parkerr/traces.html

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In article <3897EF69.BDED5ADE@umh.ac.be>, Fabian Brau 
<fab### [at] umhacbe> wrote:

> A new pattern which can do this 
> automatically could be, in fact, difficult to use no?

Not really, my idea was a curvature pattern, where the value depends on 
the curvature of the surface. So you could have the patina only be in 
concave areas, and the tips be polished metal, like the patina is worn 
off in those areas. This kind of thing is already possible with simple 
objects, but for more complex shapes a special pattern would be 
needed.(or an image would have to be used to control it)

Another idea would be a visibility pattern, where the value of the 
pattern would depend on it's visibility from a specified point. 
Something similar to slope, although very different in implementation. 
It could have an "orthographic" mode as well, and could be useful in 
placing snow or simulating the effect of fading dyes.

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

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Chris Huff wrote:
> 
> In article <3897EF69.BDED5ADE@umh.ac.be>, Fabian Brau
> <fab### [at] umhacbe> wrote:
> 
> > A new pattern which can do this
> > automatically could be, in fact, difficult to use no?
> 
> Not really, my idea was a curvature pattern, where the value depends on
> the curvature of the surface. So you could have the patina only be in
> concave areas, and the tips be polished metal, like the patina is worn
> off in those areas. This kind of thing is already possible with simple
> objects, but for more complex shapes a special pattern would be
> needed.(or an image would have to be used to control it)
> 
> Another idea would be a visibility pattern, where the value of the
> pattern would depend on it's visibility from a specified point.

Hmm.. could this be done algorithmically by using trace from a lot of
really odd angles to determine how "open" a certain point would be? (ie,
a convex surface could be hit from anywhere, but a deep concave one, or
a groove between two convex surfaces, could only be hit from angles
which approach perpendicular.)

I haven't messed with trace, so it's just an idea being tossed out...

-- 
Xplo Eristotle
http://start.at/xplosion/

"Error has no rights." - Tomas de Torquemada

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In article <38989C51.C2809A76@unforgettable.com>, 
inq### [at] unforgettablecom wrote:

> Hmm.. could this be done algorithmically by using trace from a lot of
> really odd angles to determine how "open" a certain point would be? (ie,
> a convex surface could be hit from anywhere, but a deep concave one, or
> a groove between two convex surfaces, could only be hit from angles
> which approach perpendicular.)

That is one of the methods I have been thinking of using for curvature. 
Another would be to test a bunch of points in a sphere centered around 
the evaluation point, and returning the percentage which are inside the 
object. Or shooting rays at parts of the surface close to the evaluation 
point, and using their positions and normals to calculate the 
curvature.(The last one is probably the most accurate, but is the one I 
wasn't able to complete)

For the visibility pattern, a single ray(or multiple rays with a 
specified jitter amount) would be shot at a specified point or along a 
specified direction.

I will get to work on these and see if they are at all useful...

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

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cadman wrote:

> YES YES YES!! That would make light-years of difference in realism.  I am
> curious to see where this goes.

light years measure distance...

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Homepage: http://www.faricy.net/~davidf/
___     ______________________________
 | \     |_       <dav### [at] faricynet>
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Chris Huff wrote:
> 
> Not really, my idea was a curvature pattern, where the value depends on
> the curvature of the surface. So you could have the patina only be in
> concave areas, and the tips be polished metal, like the patina is worn
> off in those areas. This kind of thing is already possible with simple
> objects, but for more complex shapes a special pattern would be
> needed.(or an image would have to be used to control it)
> 

I may be completely misinformed here, but couldn't something similar to the
current isosurface evaluation method be used to determine curvature?

Margus

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In article <3898CE3A.30E36D45@peak.edu.ee>, Margus Ramst 
<mar### [at] peakeduee> wrote:

> I may be completely misinformed here, but couldn't something similar to 
> the
> current isosurface evaluation method be used to determine curvature?

I am not sure what you mean...as I understand it, the isosurface solver 
takes samples along the ray, using the maximum gradient of the function 
to determine if there is a possible intersection between each pair of 
samples. I don't see how this could be applied to finding the curvature 
of a specific point.

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

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> > I may be completely misinformed here

:)

Margus

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metaphorically speaking...

David Fontaine <dav### [at] faricynet> wrote in message
news:3898BB89.35AA5814@faricy.net...
> cadman wrote:
>
> > YES YES YES!! That would make light-years of difference in realism.  I
am
> > curious to see where this goes.
>
> light years measure distance...
>
> --
> Homepage: http://www.faricy.net/~davidf/
> ___     ______________________________
>  | \     |_       <dav### [at] faricynet>
>  |_/avid |ontaine      <ICQ 55354965>
>
>

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