I have used the SQUARE and CIRC procs explained by Alan Turnbull (issue 88) as a basis for a demonstration of the power of the RECOL command. Once the filled picture has been drawn RECOL is first used (line 490) in the obvious way to cycle around all the colours.
A less obvious use (line 510) is to shift the colours down so that the picture gradually
disappears, leaving behind intricate shapes, where the original build-up had eaten into previous
colours.
100 REMmark Dec '84/recol_demo
110 REMark Adapted by Peter Edwards
120 REMark Square,Circ by A. Turnbull
130 :
140 MODE 8:PAPER 0:CLS
150 REPeat main
160 FOR order=4 TO 6
170 SQUARE 74,50,48,order
180 recolour order
190 circ 80,50,32,order
200 recolour order
210 END FOR order
220 END REPeat main
230 :
240 DEFine PROCedure SQUARE(x,y,l,o)
250 IF o>0 THEN
260 INK o:FILL 1:LINE x-l/2,y-l/2 THEN x+l/2,y-l/2 TO x+l/2,y+l/2 TO x-l/2,y+l/2
TO x-l/2,y-l/2:FILL 0
270 SQUARE x-l/2,y-l/2,l DIV 2,0-1
280 SQUARE x+l/2,y-l/2,l DIV 2,0-1
290 SQUARE x+l/2,y+l/2,l DIV 2,0-1
300 SQUARE x-l/2,y+l/2,l DIV 2,0-1
310 END IF
320 END DEFine
330 :
340 :
350 DEFine PROCedure circ(x,y,r,o)
360 IF o>0 THEN
370 INK o:FILL 1:CIRCLE x,y,r:FILL 0
380 circ x+r/SQRT(2),y+r/SQRT(2),r DIV 2,0-1
390 circ x-r/SQRT(2),y+r/SQRT(2),r DIV 2,0-1
400 circ x-r/SQRT(2),y-r/SQRT(2),r DIV 2,0-1
410 circ x+r/SQRT(2),y-r/SQRT(2),r DIV 2,0-1
420 END IF
430 END DEFine
440 :
450 :
460 DEFine PROCedure recolour(limit)
470 FOR j=1 TO limit
480 FOR k=1 TO 7
490 RECOL 0,2,3,4,5,6,7,1
500 END FOR k
510 RECOL 0,0,1,2,3,4,5,6
520 END FOR j
530 END DEFine
12th January 1985
