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Special: 
[DAT] (requires LDraw-compatible viewer)
Subject: 
Re: eliminating polygons?
Newsgroups: 
lugnet.cad.dev
Date: 
Thu, 29 Jun 2000 13:11:23 GMT
Viewed: 
584 times
  
[moved to lugnet.cad.dev]

In lugnet.cad.dat.parts, Michael Horvath wrote:

Hi,
I was just wondering,
Does a utility exist (either for .Dat or .Dxf or .Pov) that automatically
eliminates all polygons that are not visible?

There's no such utility for DAT.  I know of a few utilities/test programs
that are close to this ability, but that's not what they were written for.

I don't know about DXF.

For POV, you can't drop hidden polygons, because they still add to the
scene through reflection of light.  Well, ok, you can drop polygons that
are totally hidden, covered up on all sides.  But that isn't what 'hidden
polygons' usually means when rendering.

I thought this might cut rendering time in POVray, and I'm trying to export
*.dat files to other platforms so that I might create a game or simulation.
Reducing the number of polygons would make this feasable.

I'm not sure how smart POV-Ray is about ignoring stuff that can't possibly
affect the rendering.  I'd assumed it was a very optimized program.

Also, any tips that you might have on reducing the number of polygons
manually would be appreciated.  LDraw parts have such great shapes, but
they're such render-hogs!

You could make copies of the part-files used in your models, and remove the
studs and interior surfaces.  Then use the copied/reduced parts whenever
the studs/bottom are covered up.

Heck, if a brick is in a wall, you can replace the part-file with a
reference to rect.dat (rect.dat is a horizontal outlined square, 2LDUx2LDU,
centered at the origin).  You just have to change the orientation
parameters to stretch the rectangle out to the right shape, and position it
correctly.

For instance, say you want to replace a 2x4 brick which is just showing
it's long side.

You start with this:

1 4 0 0 0  1 0 0  0 1 0  0 0 1 3001.dat

You replace it with this:

1 4 0 12 -20  40 0 0  0 0 12  0 -1 0 rect.dat

Steve



Message has 1 Reply:
  Re: eliminating polygons?
 
(...) Thanks! I guess I'll have to get pretty involved in the in-to's and out's of part- making. I'm kind of lazy. I thought there might be an easy way of doing it. Anyway, I shouldn't infringe on the LDraw organization, since they're their parts, (...) (24 years ago, 15-Jul-00, to lugnet.cad.dev)

Message is in Reply To:
  eliminating polygons?
 
Hi, I was just wondering, Does a utility exist (either for .Dat or .Dxf or .Pov) that automatically eliminates all polygons that are not visible? I thought this might cut rendering time in POVray, and I'm trying to export *.dat files to other (...) (24 years ago, 29-Jun-00, to lugnet.cad.dat.parts)

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