MGHGRCOLORPLANE__DEFINE
Class Name
MGHgrColorPlane
Purpose
The MGHgrColorPlane implements a flat, coloured surface consisting
of a rectangular array of quadrilateral cells, optionally with
some of the cells omitted. Colours are either uniform over the
cells (STYLE=0) or interpolated from the vertices (STYLE=1). A
"colour plane" is a lot like an image, but has more flexibility in
the pixel geometry & shading.
The MGHgrColorPlane is used as a base for the density plot class,
MGHgrDensityPlane.
I have two different colour plane implementations: the
MGHgrColorPolygon displays data using an IDLgrPolygon and the
MGHgrColorSurface displays data using an IDLgrsurface. These two
implementations are largely interchangeable but have various
strengths and weaknesses. In the past I have dithered about which
one should be labelled "MGHgrColorPlane". Now the MGHgrColorPlane
is just a trivial subclass of one of them. Last time I looked it
was MGHgrColorSurface-see MGHgrColorPlane__Define below.
I haven't yet sorted out the full story about performance of the
two colour-plane implementations. For interpolated colour (STYLE=1)
they are about the same but for block colour (STYLE=0) the
IDLgrSurface-based implementation takes somewhat longer to draw
to a window and (I think) *much* longer to draw to a Postscript file.
I think this is because it is based on a lego-style surface.
In versions 5.4
and before, the IDLgrSurface-based implementation looked very odd
when the horizontal grid was rotated with STYLE = 0. This was
fixed in version 5.5.
Both the MGHgrColorPolygon and the MGHgrColorSurface inherits from
IDLgrModel, to which the surface or polygon is added. This avoids
the need to carry a 2-D array of Z information around with the
object.
For further information see the documentation for the
MGHgrColorPolygon and MGHgrColorSurface classes.
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Copyright (c) 2000-2014 NIWA:
http://www.niwa.co.nz/
Licensed under the MIT open source license:
http://www.opensource.org/licenses/mit-license.php
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Modification History
Mark Hadfield, 2000-12:
The name MGHgrColorPlane has been used for various classes in
the past. Now it is a trivial subclass of the polygon-based
colour plane, MGHgrColorPolygon.
Mark Hadfield, 2001-07:
Now a subclass of the surface-based colour plane,
MGHgrColorSurface.