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astDownsize

Reduce the number of vertices in a Polygon
 Description:
 This function returns a pointer to a new Polygon that contains a
subset of the vertices in the supplied Polygon. The subset is
chosen so that the returned Polygon is a good approximation to
the supplied Polygon, within the limits specified by the supplied
parameter values. That is, the density of points in the returned
Polygon is greater at points where the curvature of the boundary of
the supplied Polygon is greater.
 Synopsis:
 AstPolygon astDownsize( AstPolygon this, double maxerr, int maxvert )
 Parameters:

this

Pointer to the Polygon.

maxerr

The maximum allowed discrepancy between the supplied and
returned Polygons, expressed as a geodesic distance within the
Polygon's coordinate frame. If this is zero or less, the
returned Polygon will have the number of vertices specified by
maxvert.

maxvert

The maximum allowed number of vertices in the returned Polygon.
If this is less than 3, the number of vertices in the returned
Polygon will be the minimum needed to achieve the maximum
discrepancy specified by
maxerr.
 Returned Value:

astDownsize()

Pointer to the new Polygon.
 Notes:
 A null Object pointer (AST__NULL) will be returned if this
function is invoked with the AST error status set, or if it
should fail for any reason.
Next: astEBuf  End the current graphical buffering context
Up: AST Function Descriptions
Previous: astDistance  Calculate the distance between two points in a Frame
AST A Library for Handling World Coordinate Systems in Astronomy
Starlink User Note 211
R.F. WarrenSmith & D.S. Berry
25th February 2013
Email:starlink@jiscmail.ac.uk
Copyright (C) 2014 Science \& Technology Facilities Council