AMSTRAD CPC464, User Manual

Page: 112 / 249

Here’s an example of a program that uses all the items mentioned so far, and introduces a couple
more useful concepts. See how the first line (10) sets up the colour and ink conditions to make sure
that whatever was in the memory of the CPC464 at the time is reset to produce the expected results:
10 INK 0,0:I N K 1 , 2 6 : I N K 2 , 6 : I N K 3 , 1 8 :BORDER 0
2 0 R E M t h i s p r o g r a m s d r a w s p a t t e r n s
30 mode l:DEG
40 PRINT "3,4 or 6 sided pattern ? ";
50 LINE INPUT p$
6 0 I F p $ = ” 3 ” T H E N s a = 1 2 0 : G O T O 100
7 0 I F p $ = " 4 " T H E N s a = 1 3 5 : G O T O 100
80 IF p$="6" THEN sa=150:GOTO 100
90 GOT0 50
1 0 0 P R I N T : P R I N T “Calculating”;
1 0 5 I F p$="3" THEN ORIGIN 0,-50,0,640,0,400
E L S E O R I G I N 0 , 0 , 0 , 6 4 0 , 0 , 4 0 0
1 1 0 DIM cx(5),cy(5),r(5),lc(5)
1 2 0 DIM np(5)
1 3 0 D I M p x % ( 5 , 8 1 ) , p y % ( 5 , 8 1 )
1 4 0 s t = l
150 cx(l)= 3 2 0 : c y ( l ) = 2 0 0 : r ( l ) = 8 0
1 6 0 F O R s t = l T O 4
1 7 0 r ( s t + l ) = r ( s t ) / 2
180 NEXT st
190 FOR st=l TO 5
2 0 0 lc(st)=0:np(st)=0
2 1 0 np(st)=np(st)+l
2 2 0 p x % ( s t , n p ( s t ) ) = r ( s t )* S I N ( l c ( s t ) )
230 p y % ( s t , n p ( s t ) ) = r ( s t ) * C O S ( L c ( s t ) )
2 4 0 l c ( s t ) = l c ( s t ) + 3 6 0 / r ( s t )
245 IF (lc(st) MOD 60)= 0 T H E N PRINT ".";
2 5 0 I F l c ( s t ) < 3 6 0 T H E N 2 1 0
252 p x % ( s t , n p ( s t ) + l ) = p x % (st,l)
2 5 4 py%(s t , n p ( s t > + l ) = p y % ( s t , l )
2 6 0 N E X T s t
2 6 5 CLS:ink 1,2
270 st=l
2 8 0 G O S U B 340
29 0 L O C A T E 1,1
3 0 0 E V E R Y 2 5 , l G O S U B 510
3 1 0 E V E R Y 1 5 , 2 G O S U B 550
3 2 0 E V E R Y 5 , 3 G O S U B 590
5 3 0 GOT0 330
3 4 0 R E M d r a w c i r c l e plus 3,4 or 6 others
around it
3 5 0 c x % = c x ( s t ) : c y % = c y ( s t ) : l c ( s t)=0
3 6 0 F O R x % = 1 T O np(st)
3 7 0 MOVE cx%,cy%
/more