Chapter 2 Graphics Tutorial
2-24
Figure 2. 21. Printout of the SDP Example
The SDP command on line 3 defines a dashed pattern consisting of two lengths of black,
two lengths of white, five lengths of black, and two lengths of white. On line 11, the
DPAT command selects this pattern for stroking. The path defined by the PMZP (Path,
Move to Zero-relative Position) and PDZP (Path, Draw to Zero-relative Position) com-
mands is stroked using this pattern, with a result as shown in the figure above.
The SDP command uses the general format:
SDP pattern-number, dash1, space1, dash2, space2, ..., dash10, space10;
The value specified for pattern-number must be in the range from 11 to 20. Dash and
space lengths are specified in pairs. Up to ten dash-space pairs can be specified. The dash
length always comes first in each pair. If a pattern is to begin with a space, then specify 0
for dash1. However, if a pattern ends with a dash, the following space parameter can be
omitted.
Dash patterns defined with this command remain valid until redefined with another SDP
command, or until the printing system is turned off.
Drawing Arcs and Curves
A path can include curves as well as lines. The PARC (Path, draw ARC) and PCRP
(Path, Curve to Relative Position) commands make it possible to draw circular arcs and
arcs of more complex form.
The PARC command uses the format:
PARC x, y, radius, ang1, ang2;
where x and y describe the zero-relative coordinates of the center of the arc, radius
describes the radius of the arc, ang1 describes the arc’s starting angle, and ang2
describes the arc’s ending angle. Coordinates and radius are measured in the unit cur-
rently designated by the UNIT command, and the starting and ending angles are mea-
sured clockwise from the positive x axis.
The PARC command draws a line between the cursor position and the beginning of the
arc. See the following example:
!R! RES; UNIT C; NEWP; SPD .1;
PMZP 5, 5;
PARC 5, 5, 3, 45, 135;
STRK;
PAGE;
EXIT;
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