examples: add an asteroids game (it is currently < 400 lines of V, using gg)

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Delyan Angelov 2025-03-17 14:51:33 +02:00
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examples/asteroids/.gitignore vendored Normal file
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asteroids
asteroids.js
asteroids.wasm

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<!doctype html>
<html lang="en-us">
<head>
<meta charset="utf-8">
<meta content="text/html; charset=utf-8" http-equiv="Content-Type">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>V Asteroids</title>
</head>
<body>
<h1>V Asteroids demo</h1>
<canvas id="canvas" oncontextmenu="event.preventDefault()" tabindex="-1" width="800" height="600"></canvas>
<script type="text/javascript">
var canvasElement = document.getElementById('canvas');
var Module = {
print(...args) { console.log(...args); },
};
</script>
<script src="asteroids.js"></script>
</body>
</html>

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// Copyright (c) 2025 Delyan Angelov. All rights reserved.
// The use of this source code is governed by an MIT license that
// can be found in the LICENSE file.
module main
import gg
import gx
import math
import rand
import os.asset
import math.vec
type V2 = vec.Vec2[f32]
fn rads(degrees f32) f32 {
return f32(math.radians(degrees))
}
fn (a V2) + (b V2) V2 {
return a.add(b)
}
fn (a V2) offset(angle f32, scale f32) V2 {
return a + V2{math.cosf(angle) * scale, math.sinf(angle) * scale}
}
fn (mut a V2) wrap(b V2) {
a.x = f32(math.mod(a.x + b.x, b.x))
a.y = f32(math.mod(a.y + b.y, b.y))
}
fn V2.random(b V2) V2 {
return V2{rand.f32() * b.x, rand.f32() * b.y}
}
struct Body {
mut:
pos V2
vel V2
rotation f32
radius f32
active bool = true
}
struct Bullet {
Body
}
struct Asteroid {
Body
mut:
segments int
offsets []f32
points []f32
rotation_step f32 = 1.0
}
struct Player {
Body
mut:
is_engine_on bool
bullets int = 99
bullets_limit int = 99
fuel int = 9999
fuel_limit int = 9999
cooldown int
cooldown_frames int = 15
points []f32 = []f32{len: 8}
}
struct Game {
mut:
gg &gg.Context = unsafe { nil }
screen V2 = V2{800, 600}
player Player
bullets []Bullet
asteroids []Asteroid
score int
highscore int
ships int = 5
level int = 1
is_up bool
msg Message
}
@[params]
struct Message {
mut:
frames int
text string
size int = 40
color gx.Color
align gx.HorizontalAlign = .center
}
fn (mut a Asteroid) setup() {
a.segments = int(a.radius / 10) * 10
a.offsets = []f32{len: a.segments}
a.points = []f32{len: 2 * a.segments}
for i in 0 .. a.segments {
a.offsets[i] = a.radius + 25 * (0.5 - rand.f32())
}
}
fn (mut p Player) reset(screen V2) {
p.bullets, p.fuel = p.bullets_limit, p.fuel_limit
p.pos, p.vel = screen.div_scalar(2), V2{0, 0}
p.radius, p.rotation = 15, -90
p.active = true
}
fn (mut game Game) handle_input() {
mut p := &game.player
p.is_engine_on = false
if game.gg.is_key_down(.escape) {
exit(0)
}
if !p.active {
return
}
game.is_up = game.gg.is_key_down(.up) || game.gg.is_key_down(.w)
is_fire := game.gg.is_key_down(.space)
is_left := game.gg.is_key_down(.left) || game.gg.is_key_down(.a)
is_right := game.gg.is_key_down(.right) || game.gg.is_key_down(.d)
if is_fire && p.cooldown <= 0 && p.active {
game.add_bullet()
p.cooldown = p.cooldown_frames
}
if p.fuel >= 10 {
if game.is_up && p.active {
angle := rads(p.rotation)
p.vel += V2{0, 0}.offset(angle, 0.1)
p.fuel -= 10
p.is_engine_on = true
}
}
if p.fuel >= 1 {
if is_left {
p.rotation -= 2
p.fuel--
}
if is_right {
p.rotation += 2
p.fuel--
}
}
}
fn (mut game Game) update() {
game.msg.frames = int_max(0, game.msg.frames - 1)
mut p := &game.player
p.cooldown = int_max(0, p.cooldown - 1)
p.pos += p.vel
p.pos.wrap(game.screen)
for mut b in game.bullets {
if !b.active {
continue
}
b.pos += b.vel
if b.pos.x < 0 || b.pos.x > game.screen.x || b.pos.y < 0 || b.pos.y > game.screen.y {
b.active = false
}
}
for mut a in game.asteroids {
if !a.active {
continue
}
a.pos += a.vel
a.pos.wrap(game.screen)
a.rotation += a.rotation_step
if p.active && p.pos.distance(a.pos) <= (p.radius + a.radius) {
// player/asteroids collision
p.active = false
a.active = false
game.split_asteroid(a, p.vel.mul_scalar(0.5))
game.player.reset(game.screen)
game.score += 50
game.show_message(text: 'Your ship was destroyed.', color: gx.red, frames: 90)
game.ships--
if game.ships <= 0 {
game.ships = 5
game.score = 0
game.asteroids = []
game.add_asteroids(10)
}
}
}
for mut b in game.bullets {
if !b.active {
continue
}
for mut a in game.asteroids {
if !a.active {
continue
}
if b.active && b.pos.distance(a.pos) <= (b.radius + a.radius) {
// bullet/asteroid collision
b.active = false
a.active = false
game.score += 100
game.split_asteroid(a, b.vel.mul_scalar(0.2))
}
}
}
if game.bullets.any(!it.active) {
game.bullets = game.bullets.filter(it.active)
}
if game.asteroids.any(!it.active) {
game.asteroids = game.asteroids.filter(it.active)
}
if game.asteroids.len == 0 {
game.level++
game.ships++
game.player.reset(game.screen)
game.add_asteroids(10)
game.show_message(text: 'YOU WIN', color: gx.green, frames: 90)
}
game.highscore = int_max(game.score, game.highscore)
}
fn (mut game Game) show_message(params Message) {
game.msg = params
}
fn (mut game Game) split_asteroid(a &Asteroid, vel V2) {
if a.radius < 30 {
return
}
shrink_factor := 0.5 + 0.3 * rand.f32()
mut a1 := Asteroid{
...*a
active: true
radius: a.radius * shrink_factor
rotation_step: -a.rotation_step
}
mut a2 := Asteroid{
...*a
active: true
radius: a.radius * (1 - shrink_factor)
rotation_step: 2 * a.rotation_step
}
a1.vel = a1.vel.mul_scalar(shrink_factor) * vel
a2.vel = a2.vel.mul_scalar(1 - shrink_factor) * (V2{0, 0} - vel)
a1.setup()
a2.setup()
game.asteroids << a1
game.asteroids << a2
}
fn (mut game Game) draw() {
ws := gg.window_size()
game.screen = V2{ws.width, ws.height}
game.gg.draw_rect_filled(0, 0, game.screen.x, game.screen.y, gx.rgba(20, 20, 20, 255))
game.draw_ship()
for b in game.bullets {
game.gg.draw_circle_filled(b.pos.x, b.pos.y, 3, gx.yellow)
}
for mut a in game.asteroids {
game.draw_asteroid(mut a)
}
scenter := game.screen.div_scalar(2)
label1 := 'Level: ${game.level} Ships: ${game.ships}'
game.gg.draw_text(5, 10, label1, size: 20, color: gx.white, align: .left)
label2 := 'B: ${game.player.bullets:02} F: ${game.player.fuel:04}'
game.gg.draw_text(int(scenter.x), 10, label2, size: 20, color: gx.green, align: .center)
label3 := 'Score: ${game.score} Highscore: ${game.highscore}'
game.gg.draw_text(int(game.screen.x) - 5, 10, label3, size: 20, color: gx.white, align: .right)
if game.msg.frames > 0 {
game.gg.draw_text(int(scenter.x), int(scenter.y / 2), game.msg.text,
size: game.msg.size
color: game.msg.color
align: game.msg.align
)
}
label4 := 'Use arrows + space to control your ship. Use Escape to end the game.'
game.gg.draw_text(int(game.screen.x - 5), int(game.screen.y - 20), label4,
size: 16
color: gx.gray
align: .right
)
}
fn (game &Game) draw_ship() {
mut p := &game.player
if !p.active {
return
}
angle := rads(p.rotation)
p1 := p.pos.offset(angle, p.radius)
p2 := p.pos.offset(angle + 2.5, 0.6 * p.radius)
p3 := p.pos.offset(angle, -0.3 * p.radius)
p4 := p.pos.offset(angle - 2.5, 0.6 * p.radius)
p.points[0] = p1.x
p.points[1] = p1.y
p.points[2] = p2.x
p.points[3] = p2.y
p.points[4] = p3.x
p.points[5] = p3.y
p.points[6] = p4.x
p.points[7] = p4.y
game.gg.draw_convex_poly(p.points, gx.white)
if p.is_engine_on {
engine := p.pos.offset(angle + math.pi, 0.7 * p.radius)
game.gg.draw_circle_filled(engine.x, engine.y, 6, gx.yellow)
}
}
fn (mut game Game) draw_asteroid(mut a Asteroid) {
if !a.active {
return
}
game.gg.draw_circle_filled(a.pos.x, a.pos.y, a.radius, gx.rgba(235, 235, 255, 215))
for i in 0 .. a.segments {
angle := rads(a.rotation + f32(i) * 360 / a.segments)
p := a.pos.offset(angle, a.offsets[i])
a.points[i * 2], a.points[i * 2 + 1] = p.x, p.y
}
game.gg.draw_convex_poly(a.points, gx.rgba(155, 155, 148, 245))
}
fn (mut game Game) add_bullet() {
if game.player.bullets <= 0 {
return
}
game.player.bullets--
angle := rads(game.player.rotation)
game.bullets << Bullet{
pos: game.player.pos
radius: 3
vel: game.player.vel.offset(angle, 10)
active: true
}
}
fn (mut game Game) add_asteroids(count int) {
for _ in 0 .. count {
mut npos := V2{}
new_asteroid_loop: for {
npos = V2.random(game.screen)
for a in game.asteroids {
if a.pos.distance(npos) < (a.radius + 30) {
continue new_asteroid_loop
}
}
if game.player.pos.distance(npos) < 5 * (game.player.radius + 30) {
continue new_asteroid_loop
}
break
}
radius := 50 + 50 * (0.5 - rand.f32())
mut asteroid := Asteroid{
pos: npos
vel: (V2.random(game.screen) - V2.random(game.screen)) / game.screen
radius: radius
rotation: 360 * rand.f32()
rotation_step: 2 * (0.5 - rand.f32())
active: true
}
asteroid.setup()
game.asteroids << asteroid
}
}
fn on_frame(mut game Game) {
if game.gg.timer.elapsed().milliseconds() > 15 {
game.gg.timer.restart()
game.handle_input()
game.update()
}
game.gg.begin()
game.draw()
game.gg.end()
}
fn main() {
mut game := &Game{}
mut fpath := asset.get_path('../assets', 'fonts/RobotoMono-Regular.ttf')
game.player.reset(game.screen)
game.add_asteroids(10)
game.gg = gg.new_context(
window_title: 'V Asteroids'
width: int(game.screen.x)
height: int(game.screen.y)
frame_fn: on_frame
user_data: game
sample_count: 2
font_path: fpath
)
game.gg.run()
}