5ONERROR IF ERR=254 GOTO20 ELSE:REPO RT:PRINTERL:END 10*RAMOFF 20REM MAGIC3D by L Knight May 1994 30MODE4:DIMA%(60):DIMB%(60) 40FORY%=0TO1023 STEP4 50pD%=15:pP%=0 60FORN%=0TO60:A%(N%)=RND(2)-1:NEXT 70FORX%=0TO1279STEP4 80K%=ABS(740-X%)+ABS(512-Y%):IFK%<450 D%=K%DIV30 ELSED%=15 90L%=D%+45:pL%=pD%+45 100IFpD%>D% PROCforward:GOTO130 110IFpD%<D% PROCback:GOTO130 120P%=(pP%+1)MOD(L%+1) 130GCOL0,A%(P%):PLOT69,X%,Y% 140pP%=P%:pD%=D%:NEXT:NEXT 150*SAVE PICTURE FFFF5800 FFFF8000 155PRINTTAB(0,0)" COMPLETED "'SPC11:VD U7 160END 170 180DEFPROCforward 190I%=pD%-D% 200FORN%=0TOpL%:B%(N%)=A%((N%+pP%+1)MO D(pL%+1)):NEXT 210FORN%=0TOL%:A%(N%)=B%(N%+I%):NEXT 220P%=0 230ENDPROC 240 250DEFPROCback 260I%=D%-pD% 270FORN%=0TOpL%:B%(N%)=A%((N%+pP%+1)MO D(pL%+1)):NEXT 280FORN%=I%TOL%:A%(N%)=B%(N%-I%):NEXT 290FORN%=0TO(I%-1):A%(N%)=RND(2)-1:NEX T 300P%=0:ENDPROC 310 320REM Line 80 defines a pyramid. 330REM Alternatives for some other 340REM images are given below 350REM FURROWS:- 360REM 80 D%=5.5*SIN((X%+Y%)/100)+7 370REM MEX-HAT:- 380REM 80 K%=450-SQR((740-X%)^2+(512-Y %)^2):IFK%>0 D%=15-(SIN(K%/55))*K%/70-K% /60 ELSED%=15 390REM DISKS:- 400REM 80 IF(540-X%)^2+(700-Y%)^2<6200 0 D%=10 ELSE D%=15 410REM 81 IF(940-X%)^2+(700-Y%)^2<6200 0 D%=5 420REM 82 IF(740-X%)^2+(300-Y%)^2<6200 0 D%=0 430REM BALL:- 440REM 80 K%=(740-X%)^2+(512-Y%)^2:IFK %<93000 D%=7-((SQR(93000-K%))DIV49)MOD16 ELSED%=15 450 460REM Major variables:- 470REM D% = current depth (0 to 15) 480REM pD%= previous depth 490REM L% = current loop length 500REM pL%= previous loop length 510REM P% = current position in loop 520REM pP%= previous position in loop 530 540REM Action of PROCforward:- 550REM Line 200 transfers loop from 560REM array A% to array B%, rotating 570REM the loop so pointer pP% is at 580REM bottom. 590REM Line 210 transfers loop back, 600REM removing the bottom I% digits. 610 620REM Action of PROCback:- 630REM Line 270 - as line 200. 640REM Line 280 transfers loop back, 650REM opening gap at bottom. 660REM Line 290 fills the gap.