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 CAD / Ray-Tracing / 1580
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Subject: 
Re: Outlined part edges in L3P?
Newsgroups: 
lugnet.cad.ray, lugnet.inst
Date: 
Mon, 23 Dec 2002 09:42:06 GMT
Viewed: 
2152 times
  
"Lars C. Hassing" <lch@ccieurope.com> skrev i meddelandet
news:H7JwBt.7t1@lugnet.com...

The basic problem is, that there is no such thing as a line in PovRay.
PovRay deals with 3D objects.
Well, a line could be rendered as e.g. a black cylinder.
But suppose that a 1x1 brick and a 2x2 brick both use box.dat.
If the lines in box.dat were converted to black cylinders,
these cylinders would appear twice as big in the 2x2 brick,
because it scales box.dat twice as much as the 1x1 brick does.

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.

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

Of course, rendering time would go to the skies, but we have patience, don't
we?

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.

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.

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

Merry Christmas!
--
Anders Isaksson, Sweden
BlockCAD:  http://user.tninet.se/~hbh828t/proglego.htm
Gallery:   http://user.tninet.se/~hbh828t/gallery/index.htm



Message has 1 Reply:
  Re: Outlined part edges in L3P?
 
(...) 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 (...) (22 years ago, 23-Dec-02, to lugnet.cad.ray, lugnet.inst)

Message is in Reply To:
  Re: Outlined part edges in L3P?
 
(...) First, I don't think that it is related to the "smooth triangle" algorithm, because this is independent of the scale of the triangles, it only deals with their surface normals. The basic problem is, that there is no such thing as a line in (...) (22 years ago, 23-Dec-02, to lugnet.cad.ray, lugnet.inst)

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