Losing Height

A real ball doesn't bounce back to the same height — it loses energy every time and eventually settles.

Keep only three quarters of the speed on each bounce:

state["vy"] = -state["vy"] * 3 // 4

// is whole-number division from the Math chapter. The grid only has whole rows, so keeping whole numbers here saves you from a dot at row 7.3.

Watch the bounces in the numbers: each one starts with a smaller vy than the last, and the ball climbs less far each time before gravity wins.

Expected output

1/1 3/2 6/3 10/4 13/-4 10/-3 8/-2 7/-1 7/0 8/1 10/2 13/-3 11/-2 10/-1 10/0 11/1 13/-2 12/-1 12/0 13/-1

Need a hint?

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python

def new_game():

return {"y": 0, "vy": 0}

def update(state, keys):

state["vy"] = state["vy"] + 1

state["y"] = state["y"] + state["vy"]

if state["y"] >= HEIGHT - 1:

state["y"] = HEIGHT - 1

state["vy"] = -state["vy"] # keeps ALL the speed — take some away

return state

def draw(state):

grid = blank_grid()

grid[state["y"]][20] = "white"

return grid