Special:
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[DAT] (requires LDraw-compatible viewer)
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Subject:
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Color problem- is this a bug in L3P?
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Newsgroups:
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lugnet.cad.dat.models, lugnet.cad.ray
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Date:
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Tue, 25 Mar 2003 01:25:54 GMT
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Viewed:
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2693 times
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The attached .mpd file is showing a weird problem with colors when run
through L3P and rendered in POV-Ray.
There is a subfile that contains a single part. In there, the part's color
is set to trans-red (Color36). The parent file sets it to black (Color0).
That gets ignored in ldraw because the bottom-level part is trans-red, not
main-color. So it correctly renders as trans red.
But after running it through L3P and POV-Ray, the part in the subfile (the
finned 1x1 round brick) renders as black.
Poking through the POV-Ray code and experimenting with variations on this
led me to the keyword used to declare the parts/models ("object" or
"union"). When a file (part or model) contains only one reference to
another file (again, part or model), L3P writes:
#declare [translated_filename] {object
[reference to another file]
}
But when there are multiple references, it writes:
#declare [translated_filename] {union
[reference to another file]
[reference to another file]
}
At first glance, this makes sense. You have to use a union to contain
multiple POV-Ray objects, and POV-Ray gives a warning when you use a union
containing only one object. On the flip side, an object can only have one
other object reference. However, the downside is that color inheritence
works differently with a union than it does with an object. An object
inherits color from the containing object, while a union gets its color from
the colors of the contained objects.
This particular example may seem like a narrow test case that can easily be
worked around by coloring the subfile differently. That's true, but this
first came to my attention when Jake McKee contacted me about a problem with
rendering parts in LPub- they were inheriting yet another level, and were
actually ending up showing as light-grey because that's the default color
for maincolored parts. In LPub, you don't have fine control over everything
and in his case I don't know if there is a viable workaround.
So my question is... is this behavior a bug? Have others seen this as well?
Should L3P be writing out a union when writing models, regardless of the
number of references inside it? Is it a problem that POV-Ray throws a
warning? Does that behavior break down because of some other reason?
--
Tony Hafner
www.hafhead.com
0 FILE Untitled.ldr
0 Untitled
0 Name: Untitled.ldr
0 Author: Tony Hafner <www.hafhead.com>
0 Unofficial Model
0 ROTATION CENTER 0 0 0 1 "Custom"
0 ROTATION CONFIG 0 0
1 19 0 0 0 1 0 0 0 1 0 0 0 1 4733.DAT
1 19 0 24 0 1 0 0 0 1 0 0 0 1 3005.DAT
1 19 0 -24 0 1 0 0 0 1 0 0 0 1 3005.DAT
1 0 -10 0 0 1 0 0 0 1 0 0 0 1 side.ldr
1 0 10 0 0 -1 0 0 0 1 0 0 0 -1 side.ldr
0
0 FILE side.ldr
0 side
0 Name: side.ldr
0 Author: Tony Hafner <www.hafhead.com>
0 Unofficial Model
0 ROTATION CENTER 0 0 0 1 "Custom"
0 ROTATION CONFIG 0 0
1 36 -24 10 0 0 1 0 -1 0 0 0 0 1 4588.DAT
0
0
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