---
title: Cartridge API
description: The complete API available to every cartridge.
---

# Cartridge API

The complete API available to every cartridge. Functions are deterministic unless noted.

## Lifecycle

### `init`

`export function init(): void`

Run once when the cartridge starts.

### `update`

`export function update(): void`

Run at 60 Hz to update game state and read input.

### `draw`

`export function draw(): void`

Run after every update to emit drawing commands.

## Drawing

### `clear`

`clear(color = 0)`

Fill the canvas with one palette color.

### `pixel`

`pixel(x, y, color)`

Draw one pixel.

### `line`

`line(x0, y0, x1, y1, color)`

Draw a line between two points.

### `rect`

`rect(x, y, width, height, color, fill = false)`

Draw an outlined or filled rectangle.

### `circle`

`circle(x, y, radius, color, fill = false)`

Draw an outlined or filled circle.

### `text`

`text(value, x, y, color)`

Draw text with the built-in bitmap font.

### `sprite`

`sprite(pixels, width, height, x, y, transparent = 0)`

Draw row-major indexed sprite pixels.

### `map`

`map(tiles, columns, tileWidth, tileHeight, spritesheet, sheetColumns, x = 0, y = 0, transparent = 0)`

Draw a row-major tile map from an indexed spritesheet.

## Input

### `button`

`button(input)`

Check whether an input is currently held.

### `buttonPressed`

`buttonPressed(input)`

Check whether an input was pressed this update.

## World and camera

### `camera`

`camera(x = 0, y = 0)`

Offset subsequent drawing coordinates; call without arguments to reset.

## Deterministic utilities

### `seed`

`seed(value = 1)`

Reset the deterministic random sequence.

### `random`

`random(min = 0, max = 1)`

Return the next deterministic random number.

### `overlap`

`overlap(ax, ay, aw, ah, bx, by, bw, bh)`

Check two axis-aligned rectangles for overlap.

### `pointInRect`

`pointInRect(px, py, x, y, width, height)`

Check whether a point is inside a rectangle.

### `frame`

`frame()`

Return the current deterministic update number.

### `every`

`every(interval, offset = 0)`

Return true on a repeating frame interval.

### `after`

`after(frames)`

Return true after a frame threshold.

## Audio

### `tone`

`tone(frequency, duration = 100, volume = 0.15, wave = "square")`

Play one bounded cartridge tone.

### `sfx`

`sfx(notes, step = 80, volume = 0.15, wave = "square")`

Play up to 32 frequencies as a short effect.