pyxen.draw

The draw module draws shapes straight to the screen for one frame. Call it from update(); whatever you draw is cleared at the end of the frame, so you draw it again next frame or it disappears.

from pyxen import *

def update():
    draw.circle(64, 64, 20, fill=(1, 0.2, 0.3, 1))
    draw.line(0, 0, 128, 128, color=(1, 1, 1, 1))

Nothing is spawned and nothing persists — there is no entity to keep a handle on and nothing to destroy.

draw or a Shape component?

Pyxen gives you the same primitives twice. They look identical on screen and differ only in lifetime.

Reach for a Shape when the thing is something in your game. Reach for draw when you are painting a picture of something you already track yourself.

Colours

Every colour argument takes an (r, g, b, a) tuple with components from 0.0 to 1.0, or a Color.

draw.rect(10, 10, 40, 20, fill=(1, 0, 0, 1))        # opaque red
draw.rect(10, 40, 40, 20, fill=(1, 0, 0, 0.35))     # 35% red

The filled shapes draw nothing by default. draw.rect, draw.triangle and draw.circle start with both fill and stroke fully transparent, so a call that passes neither is invisible — that is the single most common surprise with this module. draw.line and draw.polyline default to opaque white instead, so they always show up.

Functions

draw.line(x1, y1, x2, y2, color=(1,1,1,1), width=1)

A straight line between two points.

def update():
    draw.line(0, 64, 128, 64, color=(0.3, 1, 0.5, 1), width=2)

draw.polyline(points, color=(1,1,1,1), width=1, closed=False)

A run of connected line segments.

def update():
    draw.polyline((10, 10, 40, 60, 80, 20, 110, 70),
                  color=(1, 0.8, 0.2, 1), width=2)

Points are flat on purpose: it is the shape a FloatBuffer already has, so a path you compute once can be handed straight to draw.polyline every frame without rebuilding it.

draw.rect(x, y, width, height, fill=None, stroke=None, stroke_width=1)

An axis-aligned rectangle. x, y is its corner, not its centre.

def update():
    # A health bar: dark backing, bright fill, thin outline.
    draw.rect(4, 4, 60, 6, fill=(0.1, 0.1, 0.1, 1))
    draw.rect(4, 4, 60 * health / max_health, 6, fill=(0.2, 1, 0.4, 1))
    draw.rect(4, 4, 60, 6, stroke=(1, 1, 1, 0.5))

draw.triangle(x1, y1, x2, y2, x3, y3, fill=None, stroke=None, stroke_width=1)

A triangle through three points.

def update():
    draw.triangle(64, 20, 84, 60, 44, 60, fill=(1, 1, 0.3, 1))

draw.circle(x, y, radius, fill=None, stroke=None, stroke_width=1, segments=12)

A circle around a centre point.

A circle is really a polygon. Twelve segments reads as round at small sizes; raise it for large circles and lower it when you want a visible polygon.

def update():
    draw.circle(64, 64, 24, fill=(0.2, 0.4, 1, 1), segments=32)
    draw.circle(64, 64, 30, stroke=(1, 1, 1, 0.4), segments=32)

Notes

• draw calls belong in update(). Calling them from start() draws for a single frame and then vanishes.
• Drawing happens in world coordinates, so the camera moves it. For a HUD that stays put, draw relative to camera or keep the HUD on an unmoved camera.
• Everything drawn in a frame lands above the sprites drawn that frame.