Subject:
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Re: POV difference in LDraw?
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Newsgroups:
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lugnet.cad.dev
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Date:
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Thu, 14 Dec 2000 12:13:13 GMT
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Viewed:
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505 times
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Tore Eriksson <tore.eriksson@mbox325.swipnet.se> writes:
> Is there any way to make something similar to the useful difference
> function from POV into LDraw? It's far beyond my programming skils,
> but we've made so many great improvements together so far so I
> believe that there is hope. Isn't the POV source available?
I don't think having the POV-Ray source code will help us here. The
problem with LDraw vs POV-Ray is that the difference and other
constructive geometry functions in POV-Ray use the inside vs outside
concept. Ie, a POV-Ray object can have a distinct volume. In LDraw,
we only model lines and triangles (and quads); there is no concept of
volume. So there are no volumes in LDraw from which the difference
can be constructed (nor the union).
There's also the problem that LDraw uses discrete surfaces
(ie. sixteen segments for a circle), while POV-Ray uses continous
surfaces.
Of course, there is nothing stopping somebody from defining volumes in
LDraw by certain rules and then constructing the difference. This
would probably be useful.
On a related note, I have made a function in LDraw-mode which takes an
object (ie. a collection of lines and surfaces) and cuts everything
below the x-z plane. The edge lines where the cut is done can be
added automatically. I find this useful for constructing various odd
shapes, for example the edge lines where the spherical ball joint
meets the box shape in the Technic Engine Connection Rod.
Extending this function to be able to cut below more complicated
surfaces would be useful, albeit hard to program.
Fredrik
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Message has 1 Reply:
 | | Re: POV difference in LDraw?
|
| (...) One of the main reasons I wrote my 3DSMAX to DAT converter was to use the boolean ops modelling abilities of 3DSMAX. When I created the technic wheels and tires that were basically a dish with holes bored through them, I couldn't imagine doing (...) (24 years ago, 14-Dec-00, to lugnet.cad.dev)
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Message is in Reply To:
| | POV difference in LDraw?
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| Is there any way to make something similar to the useful difference function from POV into LDraw? It's far beyond my programming skils, but we've made so many great improvements together so far so I believe that there is hope. Isn't the POV source (...) (24 years ago, 14-Dec-00, to lugnet.cad.dev)
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