SAC Command Reference Manual

XVPORT

SUMMARY

Defines the viewport for the x axis.

SYNTAX

XVPORT xvmin xvmax

INPUT

xvmin:X axis viewport minimum value. Must be in the range 0.0 to xvmax.
xvmax:X axis viewport maximum. Must be in the range xvmin to 1.0.

DEFAULT VALUES

XVPORT 0.1 0.9

DESCRIPTION

The viewport is the portion of the viewspace (see VSPACE command) in which the actual plot is drawn. The coordinate system used to define the viewspace and viewport is called a virtual coordinate system. A virtual coordinate system does not depend upon the size, shape, or resolution of a particular physical device's display surface. SAC's coordinate system runs from 0.0 to 1.0 in both the x and y directions. The lower left hand corner of the viewspace is the point (0.0, 0.0) and the upper right hand corner of the viewspace is the point (1.0, 1.0). (See the figure on the next page.) The use of this coordinate system lets you position a plot without worrying about a specific output device.

The XVPORT and YVPORT commands control where in the viewspace a specific plot is to be drawn. The default values use most of the viewspace for the plot while leaving some room on each side for axes, labels, and a title. You can place a particular plot anywhere you want using these commands. When used in conjunction with the BEGINFRAME and ENDFRAME commands, these commands let you create your own special layout by putting several different plots on the same frame.

EXAMPLES

See the example in the BEGINFRAME documentation.

SEE COMMANDS

VSPACE, BEGINFRAME

REFERENCES

Principles of Interactive Computer Graphics, Second Edition; William M. Newman and Robert F. Sproull; 1979; McGraw-Hill.

LATEST REVISION

January 8, 1983 (Version 8.0) Viewspace and Viewport Coordinates