100 ' *** SQ-2000 Plotter Program: 5-Point Star ***
110 '
120
' Initialize
130 '
140 DIM BUFFER%(360,45)
150 FOR BIT = 0 TO 7 : DOT%(7 - BIT) = 2
A
BIT : NEXT
160 X.SCALE = 20
: Y.SCALE
=
20
170 X.FACTOR = 360 / X.SCALE
: Y.FACTOR = 360 /
Y.SCALE
180 ESC$ = CHR$(27)
: LF$
=
CHR$(lO)
190 '
200 ' Plot curve
210 '
220 RADIUS1 = 10
: RADIUS2
=
2
230 Xl = 20
: Yl = 10
240 DIFF =
(RADIUS1 - RADIUS2)
250
FOR ANGLE = 0 TO 6.3 STEP .15
260 X2 =
DIFF * COS(ANGLE) + RADIUS2 * COS(DIFF /
RADIUS2 * ANGLE) + 10
270 Y2
= DIFF X SIN(ANGL) - RADIUS2 * SIN(DIFF / R
ADIUS2 * ANGL) + 10
280 '
290
' Draw a line from X1, Y1 to
X2,
Y2
300 '
310 X.LENGTH = X2 - X1
: Y.LENGTH = Y2 - Y1
320 X.STEPS
= ABS(X.LENGTH * X.FACTOR)
330 Y.STEPS = ABS(Y.LENGTH * Y.FACTOR)
340 IF X.STEPS > Y.STEPS THEN STEPS = X.STEPS ELSE
STEPS = Y.STEPS
350 IF STEPS = 0 THEN 480
360 DELTA.X = X.LENGTH / STEPS
: DELTA-Y
=
Y.
LENGTH / STEPS
370
FOR COUNT = 0 TO STEPS
380
X1 = X1 + DELTA.X * Y1 = Y1 + DELTA.Y
390 '
400 ' plot a point at Xl, Y1
410 '
420 X.POINT = X1 * X.FACTOR
* Y.FACTOR
: Y.POINT
=
Y1
430 COLUMN
=
INT(X.POINT)
440 ROW = INT(Y.POINT / 8)
450 BIT = INT(Y.POINT - ROW * 8)
79
