import stddraw

xc = .2
yc = .4
vx = .01
vy = .02

while True:
    stddraw.clear()
    line1 = stddraw.line(.25, .25, .5, .75)
    line2 = stddraw.line(.5, .75, .75, .25)
    line3 = stddraw.line(.25, .25, .75, .25)
    stddraw.point(xc, yc)
    stddraw.show()
    stddraw.show(10)
    if (xc + vx) >= line1 or (xc + vx) <= line2 or (xc + vx) >= line3:
        vx = -vx
    if (yc + vy) >= line1 or (yc + vy) <= line2 or (yc + vy) >= line3:
        vy = -vy
    xc = xc + vx
    yc = yc + vy