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> 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
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In lugnet.cad, Philippe Hurbain wrote:
> > 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
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"
configuration so I set the option 'on' at start. (it does not save this setting)
Cheers,
Paul Easter
http://www.geocities.com/pneaster/prim-gen.htm
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Paul,
> > This thread perfectly describes the problem. Unfortunately Paul didn't update
> > PrimGen...
Shame on me for these words! I should wear better glasses.
> 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"
> configuration so I set the option 'on' at start. (it does not save this setting)
Thanks a lot, Paul. Indeed it solves that issue. The official cylinder
primitives are now new style so I guess the option could be set to off now
(though most cone primitives have not been updated).
Now I have a request: could the new tangent style be applied to inside and
outside torus primitives? I noticed yesterday an ugly line appearing at the
junction between a torus and a cylinder...
Thanks anyway for this great tool!
Philo
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In lugnet.cad, Paul Easter wrote:
> In lugnet.cad, Philippe Hurbain wrote:
> 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"
> configuration so I set the option 'on' at start. (it does not save this setting)
>
> Cheers,
> Paul Easter
Paul!
I'm glad you're still around. ya know I'm still struggling with the issues
listed here:
http://news.lugnet.com/cad/dev/?n=9725
any chance for an update?
bye, w.
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