ROM Computer Magazine Archive ROM MAGAZINE ISSUE 6 — JUNE/JULY 1984 / PAGE 46

THE COVER
by Bob Cockroft

    The following is the program that produced the art on the front cover. The entire design was drawn on a graphics 8 screen. The various colours were created by using two methods: artifacting, and adjusting the colour controls on the Television. The distant spaceship was drawn and coloured completely by artifacting. If examined on a non-colour screen, its shape would be seen as a series of vertical lines. By plotting either even or odd pixels, different colours can be created. A similar, but less dramatic effect can be seen with the overlapping circles in the Atari Symbol. The varying background colour is not created with the computer. By experimenting with our televisions colour controls, we were able to get the screen to do some strange things. Multicoloured screens and other bazaar effects were seen and photographed. As the effects got stranger, we tried even more to disturb the televisions normal colour patterns. When it was all over, we had a number of interesting photographs. Although our television may never again work the same, we felt we had a cover for the sixth issue. After much discussion, we finally decided to use the photograph you see on the front cover.
    The most mathematically involved part of the cover is the Atari symbol. The circles were created by using the following formula.

x^2 +y^2 =r ^2

    The columns of circles were molded into an Atari symbol by three vertical lines. The two outside lines were exponential so that they curved upwards.

y=x^2

    The center of the circles were placed on each of these lines. The lines were then erased to reveal the shape you see.

2 P=1
4 RDU=20
5 F=85
6 CT=0:RAT=15:RAT1=RAT
7 B=130
8 C=130
10 GRAPHICS 8
20 COLOR 0
30 SETCOLOR 2,16,1
40 XP=60:YP=B
50 X=0:Y=0
100 PLOT XP+X,YP+Y
105 IF CT=0 THEN RDU=RDU-1:GOTO 400
110 X=X+1:CT=CT+1
120 Y=-1/C*(X*X)
130 RAT1=RAT1-0.155:IF CT>RAT1 THEN CT=0
140 IF X>F THEN FIN=YP+Y:GOTO 200
150 GOTO 100
199 REM * DRAW ATARI SYMBOL *
200 XP=265:YP=B:CT=0:P=2:RAT=15:RAT1=RAT:RDU=20
205 XP1=265
210 X=0:Y=0
220 PLOT XP+X,YP+Y
224 IF CT=0 THEN RDU=RDU-1:GOTO 400
230 X=X-1:CT=CT+1
240 Y=-1/C*(X*X)
250 IF X<-1*F THEN 300
255 RAT1=RAT1-0.155:IF CT>RAT1 THEN CT=0
260 GOTO 220
300 XP=INT((60+265)/2)+1:P=3:RAT=12:RAT1=RAT:RDU=20
305 X=0:Y=0:YP=B:CT=0
310 PLOT XP,YP+Y
312 IF CT=0 THEN RDU=RDU-1.45:GOT0 400
314 Y=Y-1:CT=CT+1
315 RAT1=RAT1-0.15:IF CT>RAT1 THEN CT=0
317 IF YP+Y<FIN THEN 1000
320 GOTO 310
399 REM * DRAW CIRCLES *
400 FOR XX=XP+X-RDU TO XP+X+RDU
405 COLOR 1
410 YY=SQR(RDU*RDU-((XX-(XP+X))*(XX-(XP+X))))+YP+Y
415 YYY=SQR(RDU*RDU-((XX-(XP+X))*(XX-(XP+X))))*-1+YP+Y
420 PLOT XX,YY
425 PLOT XX,YYY
490 NEXT XX
496 COLOR 0
500 IF P=1 THEN 110
510 IF P=2 THEN 230
520 IF P=3 THEN 314
999 REM *DRAW SPACESHIP *
1000 COLOR 1
1010 PLOT 145,68
1020 DRAWTO 150,50
1030 PLOT 181,68:DRAWTO 150,50
1040 PLOT 162,68:DRAWTO 150,50
1050 PLOT 150,50:DRAWTO 150,46
1060 PLOT 152,50:DRAWTO 152,46
1070 PLOT 154,49:DRAWTO 154,45
1080 PLOT 156,49:DRAWTO 156,45
1090 PLOT 148,51:DRAWTO 148,47
1100 PLOT 146,52:DRAWTO 146,48
1110 PLOT 144,52:DRAWTO 144,48
1120 PLOT 143,53:DRAWTO 143,49
1130 PLOT 141,53:DRAWTO 141,49
1140 PLOT 139,52:DRAWTO 139,48
1150 PLOT 137,51:DRAWTO 137,47
1160 PLOT 135,50:DRAWTO 135,46
1170 PLOT 133,49:DRAWTO 133,45
1180 PLOT 131,48:DRAWTO 131,44
1190 PLOT 129,47:DRAWTO 129,43
1200 PLOT 127,46:DRAWTO 127,42
1210 PLOT 125,45:DRAWTO 125,41
1220 PLOT 123,44:DRAWTO 123,40
1230 PLOT 121,43:DRAWTO 121,39
1240 PLOT 121,38:DRAWTO 121,39
1250 PLOT 122,38:DRAWTO 122,39
1260 DRAWTO 123,39:DRAWTO 123,40:DRAWTO 124,39:DRAWTO 124,40:DRAWT0 125,39:DRAWTO 125,40
1270 PLOT 126,39:DRAWTO 126,41:DRAWTO 127,39:DRAWTO 127,41:DRAWTO 128,40:DRAWTO 128,42
1280 PLOT 129,40:DRAWTO 129,42:PLOT 130,40:DRAWTO 130,43
1290 PLOT 131,40:DRAWTO 131,43:PLOT 132,40:DRAWTO 132,44:PLOT 133,41:DRAWTO 133,44
1300 PLOT 134,41:DRAWTO 134,44:PLOT 135,41:DRAWTO 135,45:PLOT 136,41:DRAWTO 136,46
1310 PLOT 137,41:DRAWTO 137,46:PLOT 138,41:DRAWTO 138,47:PLOT 139,42:DRAWTO 139,47
1320 PLOT 140,42:DRAWTO 140,48:PLOT 141,42:DRAWTO 141,48:PLOT 142,42:DRAWTO 142,49
1330 PLOT 143,42:DRAWTO 143,49:PLOT 144,42:DRAWTO 144,48:PLOT 145,43:DRAWTO 145,48
1340 PLOT 146,43:DRAWTO 146,47:PLOT 147,43:DRAWTO 147,47
1350 PLOT 148,43:DRAWTO 148,46:PLOT 149,44:DRAWTO 149,46:PLOT 150,44:DRAWTO 150,46
1360 PLOT 151,44:DRAWTO 151,46:PLOT 152,44:DRAWTO 152,45:PLOT 153,44:DRAWTO 153,45
1370 PLOT 154,44
1380 PLOT 155,44
2998 PLOT 134,45
2999 REM * DRAW MOUNTAINS *
3000 PLOT 1,50:DRAWTO 50,35
3010 DRAWTO 65,45
3020 DRAWTO 76,41
3030 DRAWTO 100,55
3040 DRAWTO 133,50
3045 PLOT 137,44
3050 DRAWTO 160,25
3060 DRAWTO 195,48
3070 DRAWTO 210,55
3080 DRAWTO 250,35
3090 DRAWTO 275,40
3100 DRAWTO 300,35
3110 DRAWTO 319,50
3120 PLOT 1,100:DRAWTO 101,100
3125 PLOT 138,100:DRAWTO 149,100
3130 PLOT 175,100:DRAWTO 185,100
3140 PLOT 224,100:DRAWTO 319,100
3199 REM * DRAW STARS *
3200 PLOT 10,10:PLOT 90,12:PLOT 300,5:PLOT 250,15:PLOT 125,14:PLOT 114,7
3205 PLOT 50,19:PLOT 129,8:PLOT 295,17
3210 PLOT 275,10:PLOT 175,25
3220 PLOT 230,8:PLOT 200,1:PLOT 205,15
3230 PLOT 212,30
3240 PLOT 75,1:PLOT 100,32
3250 PLOT 160,10
3260 PLOT 25,32

1 REM * CHECK DATA *
2 DATA 8495,427,633,480,583,517,519,965,748,227,972,741,327,315,175,33,603,230
150 DATA 7757,827,963,174,773,787,330,317,180,36,3.81,611,832,232,464,199,466,185
315 DATA 8677,555,659,829,611,218,804,290,520,86,180,871,813,214,219,224,740,844
1010 DATA 13661,40,174,892,892,886,891,903,908,906,896,893,894,891,904,899,894,898
1180 DATA 8940,893,906,892,887,882,886,891,894,454,323,449,1,17,42,14,34,475
1350 DATA 3411,45,27,43,45,59,852,731,136,135,177,179,45,182,196,183,186,190
3100 DATA 8219,175,183,864,988,985,980,540,353,373,748,340,30,639,32,989