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space-war.html
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space-war.html
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<html>
<head><title>Space War</title>
<style>
body {
display: grid;
grid-template-columns: 140px auto;
gap: 10px;
}
canvas {
background: #eee;
}
label {
display: block;
margin-top: 30px;
}
</style>
</head>
<body>
<div>
<div><button id=start>Start</button></div>
<div style="margin-top:1em;">Red</div>
<div id=red_victories>0 victories</div>
<div>Keys: w, a, s, d</div>
<div style="margin-top:1em;">Blue</div>
<div id=blue_victories>0 victories</div>
<div>Keys: arrow keys</div>
<label>
Gravity
<input type="range" id="gravity"
min="-1000" max="1000" value="300" />
</label>
<label>
Bullet range
<input type="range" id="bullet_range"
min="20" max="100" value="60" />
</label>
<label>
Bullet speed
<input type="range" id="bullet_speed"
min="1" max="10" value="3" />
</label>
<label>
Bullet scatter
<input type="range" id="bullet_scatter"
min="0" max="7" value="2.0" step="0.1" />
</label>
</div>
<canvas width=800 height=800></canvas>
<audio id='smash' src="https://soundbible.com/mp3/Smashing-Yuri_Santana-1233262689.mp3">
Your browser does not support the
<code>audio</code> element.
</audio>
<audio id='blast' src="https://soundbible.com/mp3/Blast-SoundBible.com-2068539061.mp3">
Your browser does not support the
<code>audio</code> element.
</audio>
<script>
let canvas = document.querySelector('canvas');
let ctx = canvas.getContext('2d');
const FRICTION = 1; // no friction
const MAX_SPEED = 100;
const LEFT_CODE = 37, UP_CODE = 38, RIGHT_CODE = 39, DOWN_CODE = 40;
const SHIP_POLY = [
[0, 0], [-10, 10], [20, 0], [-10, -10]];
const BULLET_POLY = [[0, 0], [4, 8], [8, 4]]
const SUN_POLY = [
[0, 0], [10, -5], [20, 0], [25, 10], [20, 20], [10, 25], [0, 20], [-5, 10]];
const smashEl = document.querySelector('#smash');
smashEl.volume = 0.3;
const blastEl = document.querySelector('#blast');
blastEl.volume = 0.8;
// list of all objects to draw
let sprites = [];
// Objects to add or remove on the next turn;
let newSprites = [], oldSprites = [];
let redVictories = 0, blueVictories = 0;
let perturbance = 0;
let gravity = 300;
let bulletRange = 60;
let bulletSpeed = 3, bulletScatter = 2.0;
let sun = null; // filled in below
let redKey = null, blueKey = null;
function polarToCartesian(polar) {
return {
dx: polar.speed * Math.cos(polar.radians),
dy: polar.speed * Math.sin(polar.radians),
}
}
function cartesianToPolar(dx, dy) {
return {
speed: Math.sqrt(dx**2 + dy**2),
radians: Math.atan2(dy, dx),
}
}
class Sprite {
constructor(poly, x, y, dx, dy, r, dr) {
this.poly = poly;
this.x = x; this.y = y;
this.dx = dx || 0; this.dy = dy || 0;
this.r = r || 0; this.dr = dr || 0; // rotation
// todo compute w, and h for bbox
this.visible = true;
this.ignoreCollision = 60;
}
checkWorldEdges() {
if (this.x < 0) this.x = canvas.width;
if (this.x > canvas.width) this.x = 0;
if (this.y < 0) this.y = canvas.height;
if (this.y > canvas.height) this.y = 0;
}
overlaps(s) {
s.tracePath();
for (let p of this.poly) {
if (ctx.isPointInPath(this.x + p[0], this.y + p[1])) return true;
}
return false;
}
handleCollisionWith(s) {
console.log('collision!');
}
checkCollisions() {
if (this.ignoreCollision > 0) {
this.ignoreCollision--;
return;
}
if (!this.visible) return;
for (let s of sprites) {
if (s === this) continue;
if (s.ignoreCollision > 0) continue;
if (!s.visible) continue;
if (this.overlaps(s)) {
this.handleCollisionWith(s);
s.handleCollisionWith(this);
}
}
}
turn() {
if (!this.visible) return;
this.x += this.dx;
this.y += this.dy;
this.r += this.dr;
this.checkWorldEdges();
this.checkCollisions();
if (sun && this !== sun) {
let sunVector = cartesianToPolar(sun.x - this.x, sun.y - this.y);
let gravVector = {
speed: gravity / sunVector.speed ** 2,
radians: sunVector.radians };
let gravAccel = polarToCartesian(gravVector);
this.dx += gravAccel.dx;
this.dy += gravAccel.dy;
}
}
tracePath() {
ctx.save();
ctx.beginPath();
ctx.translate(this.x, this.y);
ctx.rotate(this.r);
let p0 = this.poly[0];
ctx.moveTo(p0[0], p0[1]);
for (let p of this.poly)
ctx.lineTo(p[0], p[1]);
ctx.lineTo(p0[0], p0[1]);
ctx.restore();
}
draw() {
if (!this.visible) return;
this.tracePath();
if (this.ignoreCollision > 0) {
ctx.setLineDash([6, 2]);
} else {
ctx.setLineDash([]);
}
if (this.playerColor)
ctx.strokeStyle = this.playerColor;
ctx.stroke();
}
}
class Bullet extends Sprite {
constructor(playerColor, x, y, dx, dy) {
super(BULLET_POLY, x, y, dx, dy,
0, (Math.random() -0.5));
this.playerColor = playerColor;
this.ignoreCollision = 0;
this.timeToLive = bulletRange;
}
turn() {
super.turn();
this.timeToLive--;
if (this.timeToLive <0)
oldSprites.push(this);
}
handleCollisionWith(s) {
if (s.playerColor == this.playerColor) return;
super.handleCollisionWith(s);
oldSprites.push(this);
}
}
class Ship extends Sprite {
constructor(playerColor) {
super(SHIP_POLY, 0, 0);
this.playerColor = playerColor;
this.reset();
}
reset() {
this.visible = true;
this.dx = 0; this.dy = 0; this.dr = 0;
this.ignoreCollision = 60;
if (this.playerColor == 'red') {
this.x = 100; this.y = canvas.height / 2; this.r = 0;
}
else {
this.x = canvas.width - 100; this.y = canvas.height / 2; this.r = Math.PI;
}
}
turn() {
super.turn();
this.dx = this.dx * FRICTION;
this.dy = this.dy * FRICTION;
}
handleCollisionWith(s) {
if (s.playerColor == this.playerColor) return;
super.handleCollisionWith(s);
blastEl.play();
perturbance += 10;
if (this.playerColor == 'red')
blueVictories++;
else
redVictories++;
this.visible = false;
window.setTimeout(() => {
this.reset();
}, 1000);
newSprites.push(new Explosion(this.x, this.y, this.dx, this.dy, 80));
}
}
class Explosion extends Sprite {
constructor(x, y, dx, dy, maxRadius) {
super([], x, y, dx / 2, dy / 2);
this.radius = 10;
this.maxRadius = maxRadius;
this.ignoreCollisions = 1000;
}
turn() {
super.turn();
this.radius += 5;
if (this.radius > this.maxRadius)
oldSprites.push(this);
}
tracePath() {
ctx.save();
ctx.beginPath();
ctx.arc(this.x, this.y, this.radius, 0, 2* Math.PI);
ctx.restore();
}
draw() {
if (!this.visible) return;
this.tracePath();
ctx.fillStyle = 'rgb(180, 180, 180, ' + (1 - this.radius / 100) + ')';
ctx.fill();
}
}
function render() {
ctx.clearRect(0, 0, canvas.width, canvas.height);
ctx.save();
if (perturbance > 1) {
let pX = perturbance * (Math.random() - 0.5);
let pY = perturbance * (Math.random() - 0.5);
ctx.translate(pX, pY);
perturbance--;
}
for (let s of sprites) {
s.draw();
}
ctx.restore();
document.querySelector('#red_victories').innerText = redVictories + ' victories';
document.querySelector('#blue_victories').innerText = blueVictories + ' victories';
}
function mergeSprites() {
for (let oldSprite of oldSprites) {
sprites.splice(sprites.indexOf(oldSprite), 1);
nonviolentTurns = 0;
}
oldSprites = [];
if (newSprites.length < 16)
for (let newSprite of newSprites)
sprites.push(newSprite);
newSprites = [];
}
function gameLoop() {
processKeys();
mergeSprites();
for (let s of sprites) {
s.turn();
}
render();
}
sun = new Sprite(SUN_POLY, canvas.width / 2, canvas.height / 2, 0, 0, 0.3);
sun.playerColor = 'orange';
const redShip = new Ship('red');
const blueShip = new Ship('blue');
function init() {
// add sprites
sprites = [redShip, blueShip, sun];
}
function start() {
init();
window.setInterval(gameLoop, 50);
// Safari only allows playing of audio if it is first played during a user-initiated event.
for (let audio of document.querySelectorAll('audio')) {
audio.play();
audio.pause();
audio.currentTime = 0;
}
}
function turnCCW(ship) {
ship.r -= 0.1;
}
function turnCW(ship) {
ship.r += 0.1;
}
function thrust(ship) {
if (ship.dx > MAX_SPEED || ship.dy > MAX_SPEED) return;
let t = 2; // amount of thrust
let tx = t * Math.cos(ship.r);
let ty = t * Math.sin(ship.r);
ship.dx += tx;
ship.dy += ty;
}
function shoot(ship) {
if (!ship.visible) return;
const SHIP_LENGTH = 20;
let speed = bulletSpeed;
let bulletDx = speed * Math.cos(ship.r) + Math.random() * bulletScatter - bulletScatter / 2;
let bulletDy = speed * Math.sin(ship.r) + Math.random() * bulletScatter - bulletScatter / 2;
let bullet = new Bullet(
ship.playerColor,
ship.x + SHIP_LENGTH * Math.cos(ship.r), ship.y + SHIP_LENGTH * Math.sin(ship.r),
ship.dx + bulletDx, ship.dy + bulletDy);
newSprites.push(bullet);
}
function processKeys() {
if (redKey == 'a') turnCCW(redShip);
if (redKey == 'd') turnCW(redShip);
if (redKey == 'w') thrust(redShip);
if (redKey == 's') shoot(redShip);
if (blueKey == LEFT_CODE) turnCCW(blueShip);
if (blueKey == RIGHT_CODE) turnCW(blueShip);
if (blueKey == UP_CODE) thrust(blueShip);
if (blueKey == DOWN_CODE) shoot(blueShip);
}
document.querySelector('#start').addEventListener('click', (e) => {
e.target.disabled = 'disabled';
start();
});
document.querySelector('body').addEventListener('keydown', (e) => {
if (e.key == 'a' || e.key == 'd' || e.key == 'w' || e.key == 's') redKey = e.key;
if (e.keyCode == LEFT_CODE || e.keyCode == RIGHT_CODE || e.keyCode == UP_CODE || e.keyCode == DOWN_CODE) blueKey = e.keyCode;
});
document.querySelector('body').addEventListener('keyup', (e) => {
if (e.key == 'a' || e.key == 'd' || e.key == 'w' || e.key == 's') redKey = null;
if (e.keyCode == LEFT_CODE || e.keyCode == RIGHT_CODE || e.keyCode == UP_CODE || e.keyCode == DOWN_CODE) blueKey = null;
});
document.querySelector('#gravity').addEventListener(
'change', (e) => {
gravity = Number(e.target.value);
e.target.blur();});
document.querySelector('#bullet_range').addEventListener(
'change', (e) => {
bulletRange = Number(e.target.value);
e.target.blur();});
document.querySelector('#bullet_speed').addEventListener(
'change', (e) => {
bulletSpeed = Number(e.target.value);
e.target.blur();});
document.querySelector('#bullet_scatter').addEventListener(
'change', (e) => {
bulletScatter = Number(e.target.value);
e.target.blur();});
</script>
</body>
</html>