ON ERROR IF ERR=17 CHAIN @lib$ + "../examples/tools/touchide" ELSE \
      \ MODE 7 : REPORT : PRINT " at line ";ERL : END
      
      REM 'Vampire Einstein' aperiodic tessellation without reflections
      REM BBC BASIC + aagfxlib library, © Richard Russell, 03-Jun-2024
      
      MODE 9 : GCOL 1 : GCOL 135 : CLG
      INSTALL @lib$ + "aagfxlib"
      
      S = 3 : REM Overall scale
      L = S * SQR(307 + 72*SQR3)
      T = ATN(3 / (16/9 + SQR3))
      
      FOR T% = 1 TO 45
        READ X, Y, A
        PROCvampire(X, Y, A, S, 1)
        COLOR 1, 64+RND(160), 64+RND(160), 64+RND(160)
        FILL X - 120 * SINRADA + 50 * COSRADA, Y - 120 * COSRADA - 50 * SINRADA
      NEXT T%
      
      RESTORE
      FOR T% = 1 TO 45
        READ X, Y, A
        PROCvampire(X, Y, A, S, 2)
      NEXT T%
      
      REPEAT WAIT 4 : UNTIL FALSE
      END
      
      DATA 514,710,0,   662,670,0,   958,714,60,  848,311,180, 368,795,300
      DATA 770,776,120, 919,861,60,  881,1009,60, 1066,822,180,1212,780,180
      DATA 660,500,60,  258,562,240, 344,586,330, 591,244,300, 441,160,240
      DATA 256,392,300, 994,226,120, 959,714,300, 1213,780,180,1082,542,90
      DATA 1102,332,120,258,392,180, 220,710,240, 148,286,300, 220,708,120
      DATA 98,882,270,  332,1114,0,  478,1072,0,  1106,628,0,  1252,416,60
      DATA 1032,78,240, 886,120,0,   738,159,0,   480,11,240,  38,178,300
      DATA 110,432,180, 296,200,0,   1180,162,300,-112,94,240, 58,-30,270
      DATA 1068,-70,240,74,794,180,  110,431,60,  688,1094,30, 1362,694,120
      
      DEF PROCvampire(x, y, a, s, t)
      LOCAL I%, d : LOCAL DATA
      RESTORE +1
      FOR I% = 1 TO 7
        READ d : d += a
        x += L * SIN(T + RAD(d))
        y += L * COS(T + RAD(d))
        PROCside(x, y, d, s, t)
        READ d : d += a
        PROCside(x, y, d, s, t)
        x -= L * SIN(T + RAD(d))
        y -= L * COS(T + RAD(d))
      NEXT
      ENDPROC
      
      DATA 80,170,50,320,200,290,170,350,230,140,260,170,290,200
      
      DEF PROCside(x, y, a, s, t)
      LOCAL r, d : r = 9 * s : d = 8 * s
      PROC_aaline(x, y, x-d*SINRADa, y-d*COSRADa, t, TRUE, 0)
      x -= d*SINRADa + r*COSRADa : y -= d*COSRADa - r*SINRADa
      PROC_aaarc(x, y, r, r, a, 120, t, TRUE, 0)
      ENDPROC