Up and Down

Same trick, other axis.

Make the dot bounce between the top of the picture and the bottom, using state["y"] and state["dy"].

Start at y of 10 with dy of 1. The floor is HEIGHT - 1, the ceiling is 0.

If you find yourself copying the last exercise and swapping letters — good. That's the pattern working. Sideways and downwards were never different ideas.

Expected output

11/1 12/1 13/-1 12/-1 11/-1 10/-1 9/-1 8/-1 7/-1 6/-1 5/-1 4/-1 3/-1 2/-1 1/-1 0/1 1/1 2/1 3/1 4/1 5/1 6/1 7/1 8/1 9/1 10/1 11/1 12/1 13/-1 12/-1

Need a hint?

3 available · costs 5 XP each

python

def new_game():

return {"y": 10, "dy": 1}

def update(state, keys):

# Move by dy, then bounce off the top and the bottom.

return state

def draw(state):

grid = blank_grid()

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

return grid