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Subject: 
Re: Problem with Primitive Generator
Newsgroups: 
lugnet.cad
Date: 
Wed, 26 Sep 2007 18:36:16 GMT
Viewed: 
1932 times
  
I think a solution that mostly works was invented around this
time frame:

  http://news.lugnet.com/cad/dat/parts/?n=3375

Instead of using cylinder primitives with an optional line at one end
that expects to be mated with a similar cylinder primitive, you use
optional lines at both ends that share the work by dividing the curve
angle in half.  This puts the optional line control points on the
tangent plane, which allows you to mate a cylinder primitive with
another cylinder or with a quad in the tangent plane.
Yes, that's the way cylinder primitives are done, and it seems to work very
well. I think other primitives could be improved that way.

But it doesn't
work for S curves made of two cylinder primitives mated in the
opposite direction.

That case is not that bad - the angle where the middle line appears is divided
by two, so it is an improvement. Moreover the line is better accepted in that
case since the surface is locally tangent to the eye direction.

I don't think this was ever implemented for cylinders, but it might
have made it into some of the sphere primitives.  More info here,
with pictures and some discussion of the primitive generator.

  http://news.lugnet.com/cad/dat/parts/primitives/?n=350&t=i&v=a

This thread perfectly describes the problem. Unfortunately Paul didn't update
PrimGen...

Philo



Message has 1 Reply:
  Re: Problem with Primitive Generator
 
(...) I believe this was corrected back in November of 2003. There have been other updates to PrimGen since then. Look under options, 'original style cyli and cones'. I do not recall a discussion where it was ever decided to change to the "newer" (...) (16 years ago, 29-Jan-08, to lugnet.cad)

Message is in Reply To:
  Re: Problem with Primitive Generator
 
(...) I think a solution that mostly works was invented around this time frame: (URL) of using cylinder primitives with an optional line at one end that expects to be mated with a similar cylinder primitive, you use optional lines at both ends that (...) (17 years ago, 26-Sep-07, to lugnet.cad)

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