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AST_GENCURVE
Draw a generalized curve
Description:
This routine draws a general
user-defined curve defined by the supplied
Mapping. Note that the curve is transformed into
graphical coordinate space for plotting, so that a straight line in physical coordinates may result in a
curved line being drawn if the Mapping involved is non-linear. Any discontinuities in the Mapping
between physical and graphical coordinates are catered for, as is any clipping established using
AST_CLIP.
If you need to draw simple straight lines (geodesics), AST_CURVE or AST_POLYCURVE will usually
be easier to use and faster.
Invocation
CALL AST_GENCURVE( THIS, MAP )
Arguments
THIS = INTEGER (Given)
MAP = INTEGER (Given)
Pointer to a
Mapping. This Mapping should have 1 input coordinate representing offset along the required
curve, normalized so that the start of the curve is at offset 0.0, and the end of the curve is
at offset 1.0. Note, this offset does not need to be linearly related to distance along the
curve. The number of output coordinates should equal the number of axes in the current
Frame of the Plot. The Mapping should map a specified offset along the curve, into the
corresponding coordinates in the current Frame of the Plot. The inverse transformation need not
be defined.
STATUS = INTEGER (Given and Returned)
The global status.
Notes:
-
An error results if the base Frame of the Plot is not 2-dimensional.
-
An error also results if the transformation between the current and base Frames of the Plot is not
defined (i.e. the Plot’
s TranInverse attribute is zero).
Copyright (C) 2021 East Asian Observatory
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A Library for Handling
World Coordinate
Systems
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