- a sphere/spheroid can be specified as a single radius or three radii.
If all three values happen to be identical, they are collapsed to a
single value. Examples,
radius 2;
radius (2 2 2);
radius (2 3 4);
radius (2 2 4);
The search for nearest point on an ellipse or ellipsoid follows the
description given by Geometric Tools (David Eberly), which also
include some pseudo code. The content is CC-BY 4.0
In the search algorithm, symmetry is exploited and the searching is
confined to the first (+x,+y,+z) octant, and the radii are ordered
from largest to smallest.
Searching is optimized for sphere, prolate and oblate spheroids.
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