Subject:
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Re: Sphere tesselation
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Newsgroups:
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lugnet.cad.dev
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Date:
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Mon, 11 Sep 2000 19:00:21 GMT
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Viewed:
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526 times
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"Steve Bliss" <steve.bliss@home.com> wrote in message
news:ppnprssksi9anl3hi45qgq5kkbarndid1n@4ax.com...
> In lugnet.cad.dev, Travis Cobbs wrote:
>
> At some point, I'd like to replace the sphere p-files with something
> better-looking. Something like the 48\1-8sphe.dat I posted (see
> <http://news.lugnet.com/cad/dat/parts/primitives/?n=39>), but with only 5
> vertices on each edge, to fit with the standard curved p-files.
How did you generate this file? It certainly looks like it was
algorithmically generated. Don't tell me you figured out all those points
BY HAND?
I did some checks on the net. Unfortunately, I couldn't find any standard
sphere tesselation algorithms which would meet the criterion of having the
edge points line up the way we need them. There is one algorithm that comes
close, which basically recursively subdivides the faces of an octohedron,
and then "pushes" the resulting points out to the edge of a sphere.
Unfortunately, this results in points which cluster around the original
octohedron vertices. It also requires the number of steps to be a power of
2, although a simple modification could get around this problem.
--Travis Cobbs (tcobbs@san.REMOVE.rr.com)
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Message has 1 Reply:
 | | Re: Sphere tesselation
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| (...) It was a fractal-thingy--it started with a 10-vertex triangular mesh (the three points on the axes, two points along each edge, and the point at the center of the surface of the hemi-demi-semi-sphere). Then it divided each triangle in the mesh (...) (24 years ago, 12-Sep-00, to lugnet.cad.dev)
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Message is in Reply To:
| | Re: Sphere tesselation
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| (...) Nope, sorry. (...) I don't think James used any particular algorithm when he selected points for the sphere p-files. At some point, I'd like to replace the sphere p-files with something better-looking. Something like the 48\1-8sphe.dat I (...) (24 years ago, 11-Sep-00, to lugnet.cad.dev)
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