Bill Pragnell wrote:
> Jim Charter <jrc### [at] msncom> wrote:

>>but the streaking
>>effects might interest you.
> 
> They do indeed. Is that a procedural texture? Looks like you're using
> normals too. Very realistic. Any chance of a peek at the code? :)
> 

Okay, belatedly, find what I have for brick staining in p.b.scene-files.

Picasso purportedly
said, "I don't seek, I find."

Jim says, "I don't find, but I still seek,... sort of."

What is in the file, is not a finished macro by any stretch
of the imagination.  It is more a collection of half-baked
ideas.  But then you only asked for a "peek"

It took me awhile to disentangle some of the staining
ideas from some of the other things I was trying to
incorporate.

Much of the functioning is wrapped in macros.
Much of the time, this serves no necessary purpose. It
helped me organize things in an open-ended way and mix and match 
experiments.

The main discovery here for me involved the problem of the scaling
of nested textures.  Often when you nest textures, the scaling
of the contained textures will be influenced by the scaling of the
containing texture.  Apparently, I was able to divorce this connection
by defining each pattern, prescaled, as a pigment function before
nesting them.  But my testing of this was not exhaustive.

For some reason I got stubborn about forcing the boxed pattern idea
to work even though I suspect the same result might have been
achieved easier by combining a Y and an X gradient patterns.

The stain effects are in no way parameterized or regulated.  You get
different stains by manually editing the source patterns.

Included in the demo, also, is code
to apply this to isosurfaces with real displacement.  But
this experiment resulted in disappointment in two ways:

1) With multiple stones next to each other,
artifacts are produced in the
*pigmenting* of the stone.  This seems to involve the
contained_by object and/or the transformations of the
pigment. The inclusion of other primitives in the
scene will also acerbate the artifacting.  I was not
able to figure out the solution.

2) The use of the boxed pattern to try and chamfer the
edges doesn't work at all as a displacement

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