[OpenSCAD] General approach

nop head nop.head at gmail.com
Sun Jul 7 09:44:03 EDT 2019

Yes that is true because the user side of OpenSCAD uses floating point and
even snaps to a grid, so all the precision of CGAL is lost. CGAL can make
manifold geometry and then OpenSCAD breaks it by snapping to a grid and
gives it back the CGAL, which then barfs.

That said representing geometry with rational numbers is doomed because as
son as you rotate something all the coordinates become irrational.

On Sun, 7 Jul 2019 at 14:38, <arnholm at arnholm.org> wrote:

> On 2019-07-07 13:52, Parkinbot wrote:
> > OpenSCAD can have representation problems with very close vertices.
> OpenSCAD/CGAL is said to use 'fractional numbers', supposedly without
> data loss, at the price of slow execution and high memory use. However,
> the statement "OpenSCAD can have representation problems with very close
> vertices" is a characteristic for a system representing vertex
> coordinates using ordinary floating point numbers (single or double
> precision). If what you say is true, it may seem users are paying a
> price (slow execution and high memory use) for something (lossless
> computations) that isn't available?
> Carsten Arnholm
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> Discuss at lists.openscad.org
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