config.py

Part of Clumsy Bird.

"""Shared constants and asset paths for Clumsy Bird.

Nothing here is a window size. The game reads ``self.viewport_size`` in the
hook that needs it, so the ground line, the bird's rest height and the pipe
gaps all follow the window as it resizes. The two numbers below are the size
the window opens at, and only that.
"""

from pathlib import Path

# ----------------------------------------------------------------------------
# Startup window. The original game runs at 900x600 and the asset PNGs
# (bg.png 900x504, ground.png 900x96) are authored for it, so the game opens
# at that size and looks exactly like the original. Every other size works:
# the layout is computed from the live viewport, never from these.
# ----------------------------------------------------------------------------
WINDOW_WIDTH = 900
WINDOW_HEIGHT = 600

# Height of the ground strip along the bottom edge, in pixels. A property of
# ground.png rather than of the window, so it stays a constant.
GROUND_HEIGHT = 96


def ground_top(viewport_height: float) -> float:
    """Y of the top of the ground strip in a viewport this tall.

    The one place the ground line is defined: the bird lands on it, the pipe
    gaps are placed above it and the background fills the space over it.
    """
    return float(viewport_height) - GROUND_HEIGHT


# ----------------------------------------------------------------------------
# Bird tunables (translated from the MelonJS source's per-tick deltas into
# proper per-second physics so the game is framerate-independent).
# Original: gravity 0.2 px/tick @ ~60Hz, flap = -72 px instantaneous step.
# ----------------------------------------------------------------------------
BIRD_X = 120  # distance from the left edge, not a window size
BIRD_REST_FRACTION = 0.4  # rest height as a fraction of the viewport height
GRAVITY = 1500.0
FLAP_IMPULSE = 480.0
MAX_FALL_SPEED = 700.0

# ----------------------------------------------------------------------------
# Pipes: original vel.x = -5 px/tick (~300 px/s), spawn every 92 ticks
# (~1.53s), gap 240 px between pipe rims (1240 px gap value in the source
# refers to the literal sprite-distance between top + bottom pipe sprites,
# which are 1664 px tall sliding-door images. Our gap is the visible hole
# between them.)
#
# The hole is placed as a fraction of the playable height (viewport minus the
# ground strip), so it is never at the ceiling and never buried in the ground
# whatever the window is doing. At 900x600 those fractions give the same
# 80..300 px top pipe and 200 px hole the original has.
# ----------------------------------------------------------------------------
PIPE_WIDTH = 148
PIPE_HEIGHT = 1664  # source sprite height; far taller than the screen
PIPE_SCROLL_SPEED = 220.0
PIPE_GAP = 200.0  # vertical hole height in pixels
PIPE_MAX_GAP_FRACTION = 0.4  # the hole never eats more of the play area than this
PIPE_MIN_TOP_FRACTION = 0.16  # shortest top pipe, as a fraction of the play area
PIPE_MAX_TOP_FRACTION = 0.6  # longest top pipe, same units
PIPE_SPAWN_INTERVAL = 1.6

GROUND_SCROLL_SPEED = 220.0  # match pipe speed so ground & pipes move together

# ----------------------------------------------------------------------------
# Asset directory: resolved relative to this file, so the path stays valid
# regardless of cwd when a user runs the game from any directory.
# ----------------------------------------------------------------------------
ASSETS = (Path(__file__).parent / "assets").resolve()