At the heart of GKS are the Output Primitives. These are
the GKS functions that actually produce viewable results, like
drawing lines, drawing text, and so forth. Each output primitive
has an associated set of attributes, such as linewidth and line color
for lines. The programming technique is to set values
for the output primitives and then call a basic function that will
draw the desired primitive using the current settings for
the attributes.
GKS difines five output primitives:
- polyline - for drawing contiguous
line segments.
- polymarker - for marking
coordinate positions with various symmetric text symbols.
- text - for plotting text at various
angles and sizes.
- fill area - for plotting
polygonal
areas with solid or hatch fill.
- cell array - for plotting portable
raster images.
The documentation modules mentioned above discuss the primitives and the
most common functions for setting their attributes. Also
discussed are inquiry functions that exist for retrieving current
settings of attribute values.
Topics of interest related to the output primitives are:
- segmentation - saving plot
instructions for later use in the same application.
- aspect source flags - a different
way of specifying attribute values.
- escape functions - functionality
unique to NCAR GKS using the GKS "standard way of being
non-standard".