import pyxel

balle = [160, 120, 1, 1] # [x, y, vx, vy]
def update():
    balle[0] += balle[2]
    balle[1] += balle[3]
    if balle[0] < 0:
        balle[0] = 0
        balle[2] = - balle[2]
    if balle[0] > 320 - 16:
        balle[0] = 320 - 16
        balle[2] = - balle[2]
    if balle[1] < 0:
        balle[1] = 0
        balle[3] = - balle[3]
    if balle[1] > 240 - 16:
        balle[1] = 240 - 16
        balle[3] = - balle[3]
    return

def draw():
    pyxel.cls(0)
    pyxel.rect(balle[0], balle[1], 16, 16, 7)

pyxel.init(320, 240, fps=60, title="jeu")
pyxel.run(update, draw)