[OpenSCAD] Discuss manifoldness, co-incident faces edges etc

nop head nop.head at gmail.com
Wed Nov 13 16:20:23 EST 2019

Another way of putting it is CGAL has a much more complex data structure
that has explicit topology. It can created that unambiguously from a
polygon soup without any guesswork but only if it is manifold.

On Wed, 13 Nov 2019 at 21:17, nop head <nop.head at gmail.com> wrote:

> Why does is it a contradiction? A polygon mesh represents geometry and by
> finding which facets share edges it is unambiguous, so the topology of the
> geometry is preserved as long as it is manifold. For non manifold geometry
> you need a more complex data structure because edges can no longer be
> paired up unambiguously.
> On Wed, 13 Nov 2019 at 21:01, Carsten Arnholm <arnholm at arnholm.org> wrote:
>> On 13.11.2019 21:39, nop head wrote:
>> > There is no explicit topology but it is preserved.
>> This statement contradicts itself.
>>  > Once read into OpenSCAD all explicit topology is lost anyway because
>>  > it uses a polygon soup itself.
>> The obvious suggestion is to fix that for file formats with explicit
>> topology.
>> Carsten Arnholm
>> _______________________________________________
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>> Discuss at lists.openscad.org
>> http://lists.openscad.org/mailman/listinfo/discuss_lists.openscad.org
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