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AST_PRISM - Create a Prism

Description:
This function creates a new Prism and optionally initialises its attributes.

A Prism is a Region which represents an extrusion of an existing Region into one or more orthogonal dimensions (specified by another Region). If the Region to be extruded has N axes, and the Region defining the extrusion has M axes, then the resulting Prism will have (M$+$N) axes. A point is inside the Prism if the first N axis values correspond to a point inside the Region being extruded, and the remaining M axis values correspond to a point inside the Region defining the extrusion.

As an example, a cylinder can be represented by extruding an existing Circle, using an Interval to define the extrusion. Ih this case, the Interval would have a single axis and would specify the upper and lower limits of the cylinder along its length.

Invocation:
RESULT = AST_PRISM( REGION1, REGION2, OPTIONS, STATUS )
Arguments:
REGION1 = INTEGER (Given)
Pointer to the Region to be extruded.
REGION2 = INTEGER (Given)
Pointer to the Region defining the extent of the extrusion.
OPTIONS = CHARACTER $*$ ( $*$ ) (Given)
A character string containing an optional comma-separated list of attribute assignments to be used for initialising the new Prism. The syntax used is identical to that for the AST_SET routine.
STATUS = INTEGER (Given and Returned)
The global status.
Returned Value:
AST_PRISM = INTEGER
A pointer to the new Prism.
Notes:
  • Deep copies are taken of the supplied Regions. This means that any subsequent changes made to the component Regions using the supplied pointers will have no effect on the Prism.

  • A null Object pointer (AST__NULL) will be returned if this function is invoked with STATUS set to an error value, or if it should fail for any reason.


next up previous 264
Next: AST_PURGEROWS - Remove all empty rows from a table
Up: AST Routine Descriptions
Previous: AST_POLYTRAN - Fit a PolyMap inverse or forward transformation

AST A Library for Handling World Coordinate Systems in Astronomy
Starlink User Note 210
R.F. Warren-Smith & D.S. Berry
24th May 2011
E-mail:ussc@star.rl.ac.uk

Copyright (C) 2009 Science \& Technology Facilities Council