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A Library for Handling
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Description:
This
routine returns the axis values at the points that define the supplied
Region. The particular
meaning of these points will depend on the type of class supplied, as listed below under
"
Applicability:
"
.
Invocation
CALL AST_GETREGIONPOINTS( THIS, MAXPOINT, MAXCOORD,
NPOINT, POINTS, STATUS )
Arguments
THIS = INTEGER (Given)
Pointer to the Region.
MAXPOINT = INTEGER (Given)
If zero, the number of points needed to define the
Region is returned in NPOINT, but no axis values are returned and all other parameters
are ignored. If not zero, the supplied value should be the length of the first dimension
of the POINTS array. An error is reported if the number of points needed to define the
Region exceeds this number.
MAXCOORD = INTEGER (Given)
The length of the second
dimension of the POINTS array. An error is reported if the number of axes in the supplied
Region exceeds this number.
NPOINT = INTEGER (Returned)
The number of points
defining the Region.
POINTS( MAXPOINT, MAXCOORD ) = DOUBLE PRECISION
(Returned)
An array in which to return the coordinates values at the positions that define
the Region. These are stored such that the value of coordinate number COORD for point
number POINT is found in element POINTS(POINT,COORD).
STATUS = INTEGER
(Given and Returned)
The global status.
Applicability
Region
All Regions have this
attribute.
The first returned position is the Box centre, and the second is a Box corner.
The first returned position is the Circle centre, and the second is a point on the
circumference.
Returns a value of zero for NPOINT and leaves the supplied
array contents unchanged. To find the points defining a CmpRegion, use this method on
the component Regions, which can be accessed by invoking
AST_DECOMPOSE on the
CmpRegion.
The first returned position is the Ellipse centre. The second is the
end of one of the axes of the ellipse. The third is some other point on the circumference of
the ellipse, distinct from the second point.
The first point corresponds to the
lower bounds position, and the second point corresponds to the upper bounds position.
These are reversed to indicate an extcluded interval rather than an included interval. See
the Interval constructor for more information.
Returns a value of zero for
NPOINT and leaves the supplied array contents unchanged.
The positions
returned are those that were supplied when the PointList was constructed.
The positions returned are the vertex positions that were supplied when the Polygon was
constructed.
Returns a value of zero for NPOINT and leaves the supplied array contents
unchanged. To find the points defining a Prism, use this method on the component Regions,
which can be accessed by invoking AST_DECOMPOSE on the CmpRegion.
Notes:

If the coordinate system represented by the Region has been changed since it was first created,
the returned axis values refer to the new (changed) coordinate system, rather than the
original coordinate system. Note however that if the transformation from original to new
coordinate system is nonlinear, the shape within the new coordinate system may be distorted,
and so may not match that implied by the name of the Region subclass (Circle, Box, etc).
Copyright (C) 2021 East Asian Observatory
 ←Prev
 AST
A Library for Handling
World Coordinate
Systems
in Astronomy  Next→
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