'   +----------------------------------------------------------------------+
'   |                                                                      |
'   |          GRAFWIZ  Copyright (c) 1990  Thomas G. Hanlin III           |
'   |                                                                      |
'   |               The Graphics Wizard's Library for BASIC                |
'   |                                                                      |
'   +----------------------------------------------------------------------+

   REM $INCLUDE: 'grafwiz.bi'

   CONST MaxX = 639
   CONST MaxY = 479
   CONST MaxColor = 15

   DEFINT A-Z

   RANDOMIZE TIMER

   GetDisplay Adapter, Mono

   IF Adapter < 6 THEN
      PRINT "Sorry, but you must have a VGA display active to run this demo."
      END
   END IF

   X = INT(RND * MaxX \ 2)
   Y = INT(RND * MaxY \ 2)
   C = INT(RND * (MaxColor - 1) + 1)

   G12Mode 1
   G12Color C, 0

   DO
      ky$ = INKEY$
      IF LEN(ky$) THEN
         SELECT CASE UCASE$(ky$)
            CASE "C": G12Cls
            CASE "P": WHILE INKEY$ = "": WEND
            CASE ELSE
         END SELECT
      ELSE
         G12Plot X, Y
         G12Plot MaxX - X, Y
         G12Plot MaxX - X, MaxY - Y
         G12Plot X, MaxY - Y
         SELECT CASE INT(RND * 3)
            CASE 0: X = X - 1: IF X < 0 THEN X = MaxX \ 2
            CASE 1: X = X + 1: IF X > MaxX \ 2 THEN X = 0
            CASE ELSE
         END SELECT
         SELECT CASE INT(RND * 3)
            CASE 0: Y = Y - 1: IF Y < 0 THEN Y = MaxY \ 2
            CASE 1: Y = Y + 1: IF Y > MaxY \ 2 THEN Y = 0
            CASE ELSE
         END SELECT
         IF INT(RND * 20) = 1 THEN
            C = INT(RND * (MaxColor - 1) + 1)
            G12Color C, 0
         END IF
      END IF
   LOOP UNTIL ky$ = CHR$(27)

   G12Mode 0