Splitting a geosphere in half

[Gerry in Quebec]

Hi all,

Is there an easy way to use Antiprism to create a set a set of vertices that defines a hemispheric truncation plane without that plane intersecting any of the polyhedron's vertices? The case I have in mind is the 2v icosa class I geodesic sphere:

geodesic -c 1 -f 2 ico | antiview

So in summary, I'm trying to define a great circle, with maybe 5 or 10 vertices, that doesn't pass through any of the geosphere's 42 vertices.

 Thanks in advance for any help with this.

 - Gerry in Québec

[Gerry in Quebec]

I used off_trans to offset the equator of the 2v icosa, class I geosphere by 11.5 degrees (more or less arbitrary). I then added the coordinates of the 10 new vertices to the base OFF file. So, problem solved. 

Cheers,

- Gerry

[Gerry in Quebec]

Here's the result of the exercise.

[Toby Kelsey]

I can't think of an automatic way to do this but if you rotate the polyhedron appropriately with "off_trans" and then color the vertices by Z value using "off_color -v C" you can see which ones are positive or negative Z position. Then (manually) remove all vertices with negative Z coordinate (and associated faces) leaving the positive hemisphere vertices only.

Toby

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