Radio Shack TRS-80 Operation Manual page 89

Computer Graphics Operation Manual
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Example
Sample Program
SAMPLE VIEW PROGRAM
LOGICAL COLOR,BORDER,K
INTEGER FVIEW
CALL GRPINI(l)
CALL CLS
SET UP VIEW PORT
COLOR=,0
BORDER=l
CALL VIEW(21,0,8,0,42,0,16,0,COLOR,BORDER)
DRAW MULTIPLE CIRCLES
CALL SETXY(1,05,4,0)
DO 2,0 1=1,0,15,0,1,0
CALL CIRCLE(I,l,~.~,,0.,0,,0)
CONTINUE
DISPLAY VIEWPORT COORDINATES
DO 4,0 1=1,4
K=I-l
J=FVIEW(K)
WRITE (3,35)I,J
FORMAT ('2','VIEW PORT COORDINATE ',14,' IS AT',I4)
CONTINUE
PRINT EMPTY LINES
DO 6,0 1=1,6
WRITE (3,5,0)
FORMAT (lHl)
CONTINUE
END
The following two descriptions are functions in the Graphics
Subroutine Library and must be declared as LOGICAL and
INTEGER, respectively, in any routine that uses them.
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