Transformation class

The Transformation classes manage forward and reverse transformations for the Transform classes.

Synopsis

Header file:		ncarg/hlu/Transformation.h
Class name:		transformationClass
Class pointer:		<Not referenceable>
Fortran class function:	<Not referenceable>
Superclass:		Obj
Composite classes:	<None>

Resources

Local resources

+---------------------------------------------------------------+
|		Transformation Resource Set			|
|---------------------------------------------------------------|
| NAME				TYPE			ACCESS	|
|	CLASS				DEFAULT			|
|===============================================================|
| trXMinF                       NhlTFloat               RCSG    |
|       TrXMinF                         0.0                     |
|---------------------------------------------------------------|
| trXMaxF                       NhlTFloat               RCSG    |
|       TrXMaxF                         1.0                     |
|---------------------------------------------------------------|
| trXReverse                    NhlTBoolean             RCSG    |
|       TrXReverse                      False                   |
|---------------------------------------------------------------|
| trYMinF                       NhlTFloat               RCSG    |
|       TrYMinF                         0.0                     |
|---------------------------------------------------------------|
| trYMaxF                       NhlTFloat               RCSG    |
|       TrYMaxF                         1.0                     |
|---------------------------------------------------------------|
| trYReverse                    NhlTBoolean             RCSG    |
|       TrYReverse                      False                   |
|---------------------------------------------------------------|
| trLineInterpolationOn         NhlTBoolean             RCSG    |
|       TrLineInterpolationOn           False                   |
+---------------------------------------------------------------+

Composite resources

The Transformation object class has no composite class resources.

Superclass resources

The superclass of the Transformation object class does not define any resources.

Description

Transformation class objects perform forward and reverse transformations between data and NDC space for objects belonging to Transform class. You do not instantiate any of these objects directly. Rather, Transform class objects create them as needed, and provide controlled access to their resources.

The Transformation class is never itself instantiated. However, it does provide some basic resources that its subclasses may use to specify the extent and direction of the data space. Currently there are three subclasses of the Transformation class:

The LogLinTransformation provides transformations to and from a linear or logarithmic coordinate space. Either or both coordinate axes may be logarithmic.
The IrregularTransformation provides transformations to and from rectangular coordinate spaces where each coordinate axis may be either irregularly spaced, linear, or logarithmic.
The MapTransformation provides transformations to and from any of 10 different standard map projections. It disables access to all the basic Transformation class resources, since it requires more specialized resources for defining extent and direction adequately.

Support functions

There are no special support functions defined for the Transformation class or its superclass.

Status notes

1. When line interpolation is turned on, the quality of the interpolation into data space is not always very good, particularly for log plots.

Copyright

Copyright 1987-1999 University Corporation for Atmospheric Research
The use of this Software is governed by a License Agreement.

NCAR Graphics is a registered trademark of the University Corporation for Atmospheric Research.

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$Revision: 1.6 $ $Date: 1999/04/10 01:05:02 $