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 CAD / Ray-Tracing / 1582
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Subject: 
Re: Outlined part edges in L3P?
Newsgroups: 
lugnet.cad.ray, lugnet.inst
Date: 
Mon, 23 Dec 2002 12:41:05 GMT
Viewed: 
2122 times
  
In lugnet.cad.ray, Anders Isaksson writes:
Perhaps L3P could collect all the edge lines during part generation, but
defer the output until the complete model has been generated, and then write
another include file with only the edge lines/cylinders with a suitable
(uniform) radius. I think that would work, and make it quite easy to turn
the feature on/off, or change the color of the edges.

L3P works on one file at the time (it doesn't walk the tree),
and when it processes the model, the parts and submodels
have been thrown away.

Otherwise you are right. After posting I imagined I would let L3Lab
(which walks the tree) generate an edge file and append it to the pov file.

Another problem I can think of with black cylinders is,
that on "concave edges" you will only see 1/4 of the cylinder,
making it seem only half as thick as other cylinders.

Still doesn't solve the 'optional lines', does it? You'd have to skip
those...

Well, today the pov code is camera independent. But you do have a well
defined camera and optional lines could be generated for that view.

Another related item I have sometimes wondered about is how to make
rounded edges (in stead of black outlined edges), but that's more
difficult, because it would require the adjoining surfaces to be clipped.

If parts were described with CSG (start with a block, and cut away the
unwanted volume), the edge line and rounding would have the same solution -
'difference' with (different coloured) cylinders as edges.

Yeah, that's right!

I'm working on a piece library like this for the moment - Anchor
Stones/Ankersteine, as BlockCAD has spawned a brother, AnkerCAD - and it's
really fascinating what can be done quite easily with CSG. The rendering is
faster than with LDRAW parts, as those are combined of many small objects
without any structural hierarchy. Even radiosity renderings are quite
endurable.

Yes PovRay is actually quite fast even on irregular shapes.
LDraw's myriad of triangles slows it down.
Sounds exciting, AnkerCAD, can you reveal more details?

I don't know how/if this (CSG diff) works with the polygon/mesh L3P parts
(I'd better test it...)

I think it does.

Merry Christmas!

Ho ho ho ;-)
/Lars



Message has 1 Reply:
  Re: Outlined part edges in L3P?
 
(...) If you're gonna do optional lines then it'll only look correct when viewed from one direction. This means you can apply the standard cheat to solve the problem with cutoff cylinders on concave edges. Push all the edge cylinders toward the (...) (22 years ago, 24-Dec-02, to lugnet.cad.ray, lugnet.inst)

Message is in Reply To:
  Re: Outlined part edges in L3P?
 
"Lars C. Hassing" <lch@ccieurope.com> skrev i meddelandet news:H7JwBt.7t1@lugnet.com... (...) Perhaps L3P could collect all the edge lines during part generation, but defer the output until the complete model has been generated, and then write (...) (22 years ago, 23-Dec-02, to lugnet.cad.ray, lugnet.inst)

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