17-16 An Introduction to HP-GL/2 Vector Graphics EN
Study Figure 17-4 to locate these points: (0,0); (-2,2); (6,2); (6,3);
(10,0); (6,-3); (6,-2); (-2,-2); (0,0). Draw a straight line between each
point in the order listed. (You should have drawn an arrow.) This is a
simple demonstration of defining a vector image when in HP-GL/2
mode.
Note To specify a point when programming an application, you must
always give a complete X,Y coordinate pair; the X coordinate is first
and the Y coordinate second. This manual shows coordinate pairs
in parentheses (X,Y) for clarity. Do not use parentheses in your
command sequence.
Using the default HP-GL/2 coordinate system, the origin is in the
lower left corner of the PCL Picture Frame, as shown in Figure 17-5.
Using the IP or IR commands, you can move the origin to other
locations. Then, using the SC command, you can define practically
any unit coordinate system. (This process is discussed in more
detail later in this chapter under “Scaling,” and also in Chapter 19.)
Figure 17-5 The Default HP-GL/2 Coordinate System
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