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Window & Input

The window

import fastobjects as fo

win = fo.Window(1280, 720, title="my game", vsync=False, visible=True)

Window opens a native GLFW window with an OpenGL 3.3 core context. Creating it registers it as the current window: batches created afterwards attach to it automatically. vsync is off by default (benchmarks demand it); pass vsync=True to cap at the monitor's refresh rate. visible=False gives an offscreen-style window, used by the test suite.

Coordinates everywhere are pixels, y pointing down, origin at the top-left.

The frame loop

@win.frame
def update(dt: float) -> None:
    ...                       # your per-frame logic
    win.clear(0.1, 0.1, 0.1)  # background color
    win.draw(batch_a, batch_b)  # one draw call per batch, in order

win.run()
  • @win.frame registers the update function (registering again replaces it).
  • win.run() loops until the window closes: poll events → measure real dt (seconds) → call your function → swap buffers.
  • win.request_close() ends the loop from inside the update — the usual exit path (if win.keys[fo.KEY_ESCAPE]: win.request_close()).
  • Prefer manual control? poll(), clear(), swap(), and should_close are public — the benchmark arena uses exactly that loop.
  • Using a window after close() raises a clear RuntimeError (instead of crashing the interpreter).

Polled input

Input is polled state, read inside the frame function — no callbacks to wire:

@win.frame
def update(dt: float) -> None:
    if win.keys[fo.KEY_RIGHT]:          # held down right now?
        player.x += 200 * dt
    if win.mouse.left:                   # left button held?
        cursor.x = win.mouse.x           # position in pixels, y down
        cursor.y = win.mouse.y
  • win.keys[keycode] — True while the key is held. Keycodes are the glfw constants re-exported as fo.KEY_* (e.g. fo.KEY_SPACE, fo.KEY_W, fo.KEY_ESCAPE).
  • win.mouse — .x, .y (pixels), .left, .right, .middle (bools).

A complete example

This is examples/shapes_input.py in miniature:

import fastobjects as fo

win = fo.Window(800, 600, title="window & input")
shapes = fo.ShapeBatch(capacity=8)
cursor = shapes.circles(1, x=400.0, y=300.0, radius=16.0,
                        color=(1.0, 0.7, 0.1, 0.9))
player = shapes.rects(1, x=400.0, y=300.0, w=48.0, h=48.0,
                      color=(0.2, 0.9, 0.4, 1.0))

@win.frame
def update(dt: float) -> None:
    cursor.x = win.mouse.x
    cursor.y = win.mouse.y
    if win.keys[fo.KEY_RIGHT]:
        player.x += 300 * dt
    if win.keys[fo.KEY_LEFT]:
        player.x -= 300 * dt

    win.clear(0.08, 0.08, 0.10)
    win.draw(shapes)
    if win.keys[fo.KEY_ESCAPE]:
        win.request_close()

win.run()