' A program which scribbles on the screen
' Press SPACE to clear the display

SCREEN 12
RANDOMIZE TIMER
CONST w = 640, h = 480
CONST pi = 3.141592
DIM s(359), c(359)
FOR d = 0 TO 359
  s(d) = SIN(d * (pi / 180))
  c(d) = COS(d * (pi / 180))
NEXT d

x = w / 2: y = h / 2: r = INT(RND * 359)
DO
  IF RND > .5 THEN
    col = RND * 14 + 1
    dr = INT(RND * 30): IF RND > .5 THEN dr = -dr
    r = r + dr
    IF r > 359 THEN r = r - 359
    IF r < 0 THEN r = 359 + r
  END IF
  x = x + s(r): y = y + c(r)
  IF x < 0 THEN x = 0: r = 90
  IF x > w - 1 THEN x = w - 1: r = 270
  IF y < 0 THEN y = 0: r = 0
  IF y > h - 1 THEN y = h - 1: r = 180
  PSET (x, y), col
  'WAIT &H3DA, 8
  k$ = INKEY$: IF k$ = " " THEN CLS
LOOP UNTIL k$ = CHR$(27)