Game Development

Draft provides game development capabilities through its performance and cross-platform support.

Overview

Draft’s native compilation, no-GC design, and cross-platform support make it suitable for game development.

Getting Started

Create Game Project

draft new my-game --template game
cd my-game

Project structure:

my-game/
├── draft.toml
├── assets/
│   ├── sprites/
│   ├── sounds/
│   └── shaders/
├── src/
│   ├── main.draft
│   ├── game.draft
│   ├── player.draft
│   └── enemy.draft
└── draft.toml

Game Loop

import game

action main()
    @engine = @game#Engine::new("My Game", 800, 600)

    @engine#on_start(fn() =>
        load_assets()
        spawn_player()
    fin action.)

    @engine#on_update(fn(@dt) =>
        update_physics(@dt)
        update_entities(@dt)
        check_collisions()
    fin action.)

    @engine#on_render(fn() =>
        clear_screen()
        draw_entities()
        draw_ui()
    fin action.)

    @engine#run()
fin action.

Entities

import game

record Entity
    x: Float
    y: Float
    vx: Float
    vy: Float
    sprite: Sprite
    health: Int
fin record.

impl Entity
    action update(@self: mut Entity, @dt: Float)
        @self#x = @self#x + @self#vx * @dt
        @self#y = @self#y + @self#vy * @dt
    fin action.

    action draw(@self: Entity)
        @game#draw_sprite(@self#sprite, @self#x, @self#y)
    fin action.
fin impl.

Sprites

import game

action load_sprites()
    @player_sprite = @game#load_sprite("assets/player.png")
    @enemy_sprite = @game#load_sprite("assets/enemy.png")
    @bullet_sprite = @game#load_sprite("assets/bullet.png")
fin action.

action draw_player(@player: Entity)
    @game#draw_sprite(@player#sprite, @player#x, @player#y)
fin action.

Input

import game

action handle_input(@player: mut Entity)
    if @game#key_pressed(@game#KEY_LEFT)
        @player#vx = -200
    else if @game#key_pressed(@game#KEY_RIGHT)
        @player#vx = 200
    else
        @player#vx = 0
    fin if.

    if @game#key_pressed(@game#KEY_SPACE)
        shoot(@player)
    fin if.
fin action.

Gamepad

import game

action handle_gamepad()
    @pad = @game#gamepad(0)

    if @pad#button_pressed(@game#BUTTON_A)
        jump()
    fin if.

    @axis_x = @pad#axis(@game#AXIS_LEFT_X)
    @axis_y = @pad#axis(@game#AXIS_LEFT_Y)
fin action.

Physics

import game

action update_physics(@dt: Float)
    for @entity in @entities
        @entity#vy = @entity#vy + @game#GRAVITY * @dt
        @entity#x = @entity#x + @entity#vx * @dt
        @entity#y = @entity#y + @entity#vy * @dt
    fin for.
fin action.

Collision Detection

import game

action check_collisions()
    for @bullet in @bullets
        for @enemy in @enemies
            if @game#collides(@bullet, @enemy)
                @enemy#health = @enemy#health - 1
                @bullets#remove(@bullet)
            fin if.
        fin for.
    fin for.
fin action.

Collision Shapes

import game

@rect = @game#Rect::new(@x, @y, @width, @height)
@circle = @game#Circle::new(@x, @y, @radius)

if @game#rect_collides(@rect_a, @rect_b)
    handle_collision()
fin if.

if @game#circle_collides(@circle_a, @circle_b)
    handle_collision()
fin if.

Audio

import game

action load_audio()
    @jump_sound = @game#load_sound("assets/jump.wav")
    @explosion_sound = @game#load_sound("assets/explosion.wav")
    @bgm = @game#load_music("assets/bgm.ogg")
fin action.

action play_sounds()
    @game#play_sound(@jump_sound)
    @game#play_music(@bgm, loop: true)
fin action.

Particles

import game

action create_explosion(@x: Float, @y: Float)
    @emitter = @game#ParticleEmitter::new()
    @emitter#position(@x, @y)
    @emitter#count(100)
    @emitter#speed(100, 300)
    @emitter#life(0.5, 1.5)
    @emitter#color(@game#RED, @game#YELLOW)
    @emitter#emit()
fin action.

Camera

import game

action setup_camera()
    @camera = @game#Camera::new()
    @camera#follow(@player)
    @camera#zoom(2.0)
    @camera#bounds(0, 0, 2000, 2000)
fin action.

Tilemaps

import game

action load_level()
    @tilemap = @game#Tilemap::new("assets/level1.tmx")
    @tilemap#layer("background")
    @tilemap#layer("collision")
    @tilemap#layer("foreground")
fin action.

action draw_tilemap()
    @game#draw_tilemap(@tilemap, @camera#x, @camera#y)
fin action.

UI

import game

action draw_hud()
    @game#draw_text("Score: " + string(@score), 10, 10)
    @game#draw_text("Lives: " + string(@lives), 10, 30)
    @game#draw_health_bar(@player#health, 10, 50, 200, 20)
fin action.

Scene Management

import game

action main()
    @engine = @game#Engine::new("My Game", 800, 600)

    @engine#add_scene("menu", fn() => MenuScene::new())
    @engine#add_scene("game", fn() => GameScene::new())
    @engine#add_scene("gameover", fn() => GameOverScene::new())

    @engine#switch_scene("menu")
    @engine#run()
fin action.

Shaders

import game

action load_shaders()
    @shader = @game#Shader::new()
    @shader#vertex("assets/shaders/vertex.glsl")
    @shader#fragment("assets/shaders/fragment.glsl")
    @game#use_shader(@shader)
fin action.

Networking (Multiplayer)

import game
import websocket

action connect_to_server()
    @ws = @websocket#connect("ws://game-server.example.com")
    @ws#on_message(fn(@data) =>
        handle_network_message(@data)
    fin action.)
fin action.

action send_position(@x: Float, @y: Float)
    @ws#send(json#stringify({
        "type", "position",
        "x", @x,
        "y", @y
    }))
fin action.

Save System

import game
import json

action save_game()
    @save_data = {
        "level", @current_level,
        "score", @score,
        "lives", @lives,
        "position", {@player#x, @player#y}
    }
    @game#save("save.dat", @json#stringify(@save_data))
fin action.

action load_game()
    @data = @game#load("save.dat")
    @save = @json#parse(@data)
    @current_level = @save["level"]
    @score = @save["score"]
fin action.

Performance Tips

Object Pooling

import game

record BulletPool
    bullets: Array<Bullet>
    active: Int
fin record.

impl BulletPool
    action new(@size: Int) -> BulletPool
        @bullets = []
        for @i in 0..@size
            @bullets#push(Bullet::new())
        fin for.
        return BulletPool { bullets: @bullets, active: 0 }
    fin action.

    action get(@self: mut BulletPool) -> Bullet?
        if @self#active < @self#bullets#length
            @bullet = @self#bullets[@self#active]
            @self#active = @self#active + 1
            return @bullet
        fin if.
        return none
    fin action.
fin impl.

Spatial Partitioning

import game

action setup_spatial_hash()
    @grid = @game#SpatialHash::new(64)  @// Cell size
    for @entity in @entities
        @grid#insert(@entity)
    fin for.
fin action.

action query_nearby(@x: Float, @y: Float, @radius: Float) -> Array<Entity>
    return @grid#query(@x, @y, @radius)
fin action.

Building

Desktop

draft build --target native --release

Web

draft build --target wasm --release

Mobile

draft build --target mobile --release

Deployment

@// Desktop
draft deploy --target windows
draft deploy --target macos
draft deploy --target linux

@// Web
draft deploy --target wasm --hosting itch.io

@// Mobile
draft deploy --target ios
draft deploy --target android

Performance Targets

Metric	Target
Frame rate	60 FPS
Frame time	< 16ms
Draw calls	< 1000
Memory	< 256 MB
Load time	< 3s