DECLARE SUB particle.1 (x.1!, y.1!, cir!, x.bnd!, y.bnd!, x.bnd.s!, y.bnd.s!, drct.x!, drct.y!, c!)

'*******************************************************************
'*
'*      This is a program that has balls. . .
'*      An artistic example, referencing limits on an object with
'*      linear motion.
'*              
'*      Written by:Paul Graham             pmg "06"
'*                 paul154@hotmail.com
'*
'*

x.bnd = 210
y.bnd = 110

x.bnd.s = 425
y.bnd.s = 380

x.bnd.i = x.bnd
y.bnd.i = y.bnd

x.bnd.s.i = x.bnd.s
y.bnd.s.i = y.bnd.s

x.1 = x.bnd + 1
y.1 = y.bnd + 1

x.2 = 10
y.2 = 10

cnt = 0

cir = 10
cir.1 = 20

'x1 = -1
'y1 = 301

c.1 = 2

drct.x.1 = -2
drct.y.1 = 2

PRINT "Press Esc to exit. . ."
LOCATE 1, 1

SLEEP 2

SCREEN 12

DO

        delay = 0
                WHILE delay < 90
                        delay = delay + 1
                WEND

VIEW SCREEN (0, 0)-(639, 479), 0, 1
VIEW SCREEN (x.bnd, y.bnd)-(x.bnd.s, y.bnd.s), 0, 1

x.bnd = CLNG(x.bnd.i + 150 * SIN(mov + 15))
y.bnd = CLNG(y.bnd.i + 80 * COS(mov))

x.bnd.s = CLNG(x.bnd.s.i + 150 * SIN(mov + 35))
y.bnd.s = CLNG(y.bnd.s.i + 80 * COS(mov + 15))

particle.1 x.1, y.1, cir.1, x.bnd, y.bnd, x.bnd.s, y.bnd.s, drct.x.1, drct.y.1, c.1

CIRCLE (x.2 + x.1, y.2 + y.1), 5, c + 1
'LINE (x.bnd, y.bnd)-(x.bnd.s, y.bnd.s), 1, B

mov = mov + .009

LOOP WHILE INKEY$ <> CHR$(27)

SUB particle.1 (x.1, y.1, cir, x.bnd, y.bnd, x.bnd.s, y.bnd.s, drct.x, drct.y, c)

IF x.1 > x.bnd - 1 AND x.1 < x.bnd.s + 1 AND drct.x = -2 THEN
        x.1 = CLNG(x.1 + drct.x + .01)
        IF x.1 - cir < x.bnd THEN
                drct.x = 2
        END IF
END IF

IF x.1 > x.bnd - 1 AND x.1 < x.bnd.s + 1 AND drct.x = 2 THEN
        x.1 = CLNG(x.1 + drct.x)
        IF x.1 + cir > x.bnd.s THEN
                drct.x = -2
        END IF
END IF

IF y.1 > y.bnd - 1 AND y.1 < y.bnd.s + 1 AND drct.y = 2 THEN
        y.1 = CLNG(y.1 + drct.y + .03)
        IF y.1 + cir > y.bnd.s THEN
                drct.y = -2
        END IF
END IF

IF y.1 > y.bnd - 1 AND y.1 < y.bnd.s + 1 AND drct.y = -2 THEN
        y.1 = CLNG(y.1 + drct.y)
        IF y.1 - cir < y.bnd THEN
                drct.y = 2
        END IF
END IF

CIRCLE (x.1, y.1), cir, c

END SUB