Reflections - Epson FX-80 User Manual

Let's try this out with the current program. Here are the changes
needed to plot the lower right corner:
3~
D=SQR(R
A
2 + C
A
2)
4~
IF
INT(D+.5)=2~
THEN A(R,C)=l
13~ LPRINT CHR$(27)1f*IfCHR$(5)CHR$(N)CHR$(~);
l
-_
....... .
The new figure is created by moving the center of the circle from
(11,11) to (0,0) and increasing the radius from 10 to 20.
Reflections
Once the desired image is stored in the array, it can be rotated and
reflected in several different directions. It's
all
done with mirrors; at
least, it looks like mirror reflections when you are done. The mirror
effect is created by reading the array in different directions.
The array is currently read from left to right, seven rows at a time,
but it is just as easy to read it in the reverse order. Add this line:
14~
FOR C=N TO 1 STEP -1: GOSUB
18~:
NEXT C
And double the graphics width setting in line 130:
13~
LPRINT
CHR$(27)1f*IfCHR$(5)CHR$(2*N)CHR$(~);
r
Change N to 2*N
Now RUN it.
I I
ft,
l
.........
_--
...... ..
The left half of the figure is the mirror image of the right half. With a
few more changes, the program can read the array upside down and
double the output again. Add these lines:
177