Subject: Polys and Sorting

From: Chris Hand <[email-masked]>
Date: Sat, 8 Aug 92 23:12:37 BST

I hope these qns are of general interest:

1. I have created a .FIG file with a fairly large number of polys.
   There seem to be quite a few errors in terms of things being visible
   when they shouldn't.

  Can I fix this using the "sort" parameter in the .FIG file?  What does
  the numeric argument (eg. "sort 768") refer to?  I tried "768" but this
  didn't fix the errors.  The docs don't give much away.

  Am I right in thinking that all polys must be specified with vertices
  ANTI-clockwise from outside?  (Some of Dave's mail messages say "clockwise",
  but the docs with demo3 say "CCW" -- is that a typo?).

2. I have a .PLG of a pentangular (?) prism.  The end polys are
   5-pointed stars.  I suppose these count as "concave" polygons?
   They don't get drawn properly anyway...

I'm looking forward to getting hold of release 4... this thing has
come on in leaps and bounds over the last month or so!

Cheers,

Chris

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From: Dave Stampe-Psy+Eng <dstamp@watserv1>
Date: Mon, 10 Aug 92 12:03:54 -0400

The sort 768 does sorting by object insted of poly.  It's a bit of 
trial-and-error to see what looks best.  I took another look at visibility  stuff: still no better fast-and-good ways yet.  I'd hate to cut the speed
by a factor of 3...

I'd have to see the PLG file.  But multisided polys work fine,
as long as they're coplanar!

- Dave STampe