All your work is related to a
working surface. This can
be either one of the three standard planes (parallel to
two axis) or it can be a surface of arbitrary shape.
Such a surface must be represented by a mathematical
description; MegaCads uses a formulation of Coons [1]
to express the surface in terms of two variables u
and v.
To create a Coons surface you select a surface consisting
of points (imported
geometry or created by
interpolation)
and MegaCads calculates the spline coefficients for the
surface.
The surface looks identically compared to the parent point data.
If the boundaries should have the same point distribution like the parent
data it can be transformed using the
MapPoints function into a spline with a point distribution.
[1] Hoschek/Lasser: Grundlagen der geometrischen Datenverarbeitung,
Teubner Verlag
Usage:
Result:
- Four polygon entities (not selectable, invisible)
- Four spline entities
- Coons mesh
Script process and parameter: def_coons_splines
- Index of 2d polygon grid which should be represented by a Coons surface
{Build by Martin Hepperle}
{Rebuild 845: Saturday, 31, 1997 at 11:46:32, March, by Olaf Brodersen}