POV-Ray : Newsgroups : povray.binaries.animations : QUILTED pattern as normal-- odd behavior? Server Time: 12 Dec 2018 21:08:06 GMT
  QUILTED pattern as normal-- odd behavior? (Message 1 to 1 of 1)  
From: Kenneth
Subject: QUILTED pattern as normal-- odd behavior?
Date: 29 Apr 2018 18:50:01
Message: <web.5ae6126fe8495210a47873e10@news.povray.org>
While playing around with my recent multi-colored brick code, I noticed
something strange about the QUILTED pattern, when used as a normal. To try and
see what's going on, I did a much simpler animation test, of just the normal on
a large box.

The docs say that the quilted pattern-- when used as a normal-- is somewhat
different from its pigment implementation. I'm curious to know what the '3-D
shape' of that normal pattern is. The docs mention a cube-- "The squares are
actually 3-D cubes that are 1 unit in size"-- so I've always assumed that the
appearance of the pattern would be the same on all six sides of that spatial
cube. But the animation results of the normal are...odd.

There appears to be a 'discontinuity' in the pattern-- or rather, the pattern
seems to be 'truncated' instead of continuous. Sorry that I can't be more
precise.

The box pigment is just rgb .2. There are four un-moving colored lights in the
scene,  just skimming the box surface, arranged to show the normal's behavior as
it moves in -z.

        normal{
                  quilted
                  scale 1
                  bump_size 3
                  translate -3.2*clock*z
                  translate -.0001*z
              }
BTW, the slight -.0001 offset is to eliminate what looks like a 'coincident
pattern'  appearance (for want of a better term) when the normal is applied to a
typical un-translated box; the X/Y plane at z=0 sometimes shows 'speckles'.  But
I think it depends on the impinging light's angle to the surface; it's difficult
to reproduce.


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Attachments:
Download 'quilted_as_normal_1.mp4.mpg' (1034 KB)

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