Games (pyzed.game)

pyzed.game holds small helpers for real-time games: held keys, movement, collisions, pixel sprites, particles and screen shake. They are plain Python built on pyzed.draw, so they also work in screenshots and tests. See Making games for complete examples.

from pyzed import draw, game

def tick(self, dt):                      # pz.frames(self.tick) in subscriptions()
    self.x += game.axis(("left", "a"), ("right", "d")) * 300 * dt
    self.sparks.update(dt)

def view(self):
    return pz.canvas([draw.background("#0b0e14"), *game.glow(self.x, 200, 18, "#74ade8"),
                      *self.sparks.shapes()], width=400, height=300)

Keys

pressed

pressed()

The keys held down right now, as a frozenset of names without modifiers ("left", "space", "a"…). Also available as pz.pressed().

is_pressed

is_pressed(*keys, held=None)

Whether any of keys is held down (held replaces pressed(), for tests). Also available as pz.is_pressed().

axis

axis(negative, positive, *, held=None)

-1, 0 or 1 from two groups of keys: axis(("left", "a"), ("right", "d")).

vector

vector(
    left=('left', 'a'),
    right=('right', 'd'),
    up=('up', 'w'),
    down=('down', 's'),
    *,
    held=None,
)

A direction (x, y) of length 0 or 1 from four groups of keys (arrows and WASD by default); diagonals are normalized.

Math

clamp

clamp(value, low, high)

value limited to [low, high].

lerp

lerp(a, b, t)

The value t of the way from a to b (t from 0 to 1).

Collisions

Rect

@dataclass
class Rect(x, y, w, h)

An axis-aligned box (x, y is the top-left corner) with left, right, top, bottom, center, overlaps(other), contains(x, y), moved(dx, dy) and shape(**paint) (a draw.rect).

circle_rect

circle_rect(cx, cy, r, rect)

Where a circle hits a Rect: the push-out direction (nx, ny), or None. A ball bounces with if nx: vx = abs(vx) * nx and if ny: vy = abs(vy) * ny.

Drawing

rgba

rgba(color, alpha=1.0)

color ("#rrggbb[aa]" or a tuple) as an (r, g, b, a) tuple with alpha applied.

glow

glow(x, y, radius, color, *, layers=4, strength=0.5, core=True)

A soft light: translucent circles growing around (x, y) (bloom on a canvas). strength is the opacity of the innermost halo; core=False leaves out the solid circle.

sprite

sprite(rows, palette, x=0.0, y=0.0, *, scale=1.0, flip=False)

Pixel art from text: each character of rows is a pixel colored by palette (missing characters are transparent). One shape per color, so a sprite stays cheap whatever its size.

Effects

Particles

class Particles

Sparks, smoke, explosions: short-lived dots that move, fall and fade out. Call burst(x, y, …) when something happens, update(dt) every frame and draw shapes(); gravity, drag and limit tune them.

Shake

class Shake

Screen shake: kick(8) on a hit, update(dt) every frame, and start the canvas shapes with *shake.shapes() (a translate) so everything moves together.