Graphics Programming for Web Developers

Graphics for Web Devs
Jarrod Overson - Shape Security
@jsoverson

Yes, we're not game developers.
But what are you looking for in your applications?

• 60 FPS
• Beautiful graphics
• Responsive Interaction
• Smooth animations

When I say "video games"
think: "performance critical graphic applications"

The web is one of the only computer
platforms that hasn't grown with video
games pushing the edge.
Why?

The web may not need games.
But losing that discipline has handicapped us.

So where do we start?
<canvas>

document.createElement('canvas');
<canvas>
or

canvas.width = 1280;
canvas.height = 720;

var context = canvas.getContext('2d');
or "webgl"

context.fillStyle = 'MediumAquaMarine';
context.fillRect(10, 10, 100, 100);

for (var i = 0; i < 500; i++) {
context.fillRect(10 + i, 10 + i, 100, 100);
}

for (var i = 0; i < 500; i++) {
context.clearRect(0, 0, canvas.width, canvas.height);
context.fillRect(10 + i, 10 + i, 100, 100);
}

setTimeout(draw, 1000/60)
requestAnimationFrame(draw)

var i = 0;
function draw() {
if (i < 500) i++;
context.fillRect(i + 10, i + 10, 100, 100);
requestAnimationFrame(draw);
}
draw();

var i = 0;
function draw() {
if (i < 500) i++;
}
draw();
First we update our state.

var i = 0;
function draw() {
if (i < 500) i++;
}
draw();
Then we render our current state.

var i = 0;
function draw() {
if (i < 500) i++;
}
draw();
And we do it all over again.

function loop() {
update();
render();
requestAnimationFrame(loop);
}
loop();

Particle System
Particles Emitters

class ParticleSystem {
constructor() {
this.particles = [];
this.emitters = [];
}
}

class Particle {
constructor(position, velocity, acceleration) {
this.position = position;
this.velocity = velocity;
this.acceleration = acceleration;
}
}

class Particle {
this.position = position || {x: 0, y: 0};
this.velocity = velocity || {x: 0, y: 0};
this.acceleration = acceleration || {x: 0, y: 0};
}
}

class Vector {
constructor(x, y) {
this.x = x || 0;
this.y = y || 0;
}
}

class Particle {
this.position = position || new Vector(0, 0);
this.velocity = velocity || new Vector(0, 0);
this.acceleration = acceleration || new Vector(0, 0);
}
}

class Emitter {
constructor(point, velocity) {
this.position = point || new Vector(0, 0);
this.velocity = velocity || new Vector(0, 0);
}
}

constructor(width, height) { /* …snipped… */ }
render(context) {
context.clearRect(0, 0, this.width, this.height);
this.emitters.forEach(emitter => emitter.render(context));
this.particles.forEach(particle => particle.render(context));
}
}

class Particle {
constructor(position, velocity, acceleration) { /* … */ }
render(context) {
context.fillStyle = 'red';
context.fillRect(this.position.x, this.position.y, 2, 2);
}
}

var system = new ParticleSystem(width, height);
system.emitters.push(new Emitter(new Vector(10, 10)));
system.particles.push(new Particle(new Vector(20, 20)));
function loop() {
system.render(context);
window.requestAnimationFrame(loop);
}
loop();

var system = new ParticleSystem(width, height);
system.addEmitter(320, 180);
function loop() {
system.update();
system.render(context);
window.requestAnimationFrame(loop);
}
loop();

class Emitter {
constructor(position, velocity) { /* … */ }
render(context) { /* … */ }
emitParticle() {
return new Particle(this.position.clone(), this.velocity.clone());
}
}

class Particle {
constructor(position, velocity, acceleration) { /* … */ }
render(context) { /* … */ }
update() {
this.velocity.add(this.acceleration);
this.position.add(this.velocity);
}
}

constructor(width, height) { /* … */ }
addEmitter(x, y, velX, velY) { /* … */ }
update() {
this.emitters.forEach(
emitter => this.particles.push(emitter.emitParticle())
);
this.particles = this.particles.filter(particle => {
particle.update();
let pos = particle.position;
let outOfBounds = pos.x > this.width || pos.y > this.height ||
pos.x < 0 || pos.y < 0
return !outOfBounds;
})
}
}

emitParticle() {
// Define a maximum angle range in radians.
let spread = Math.PI / 32;
// Use an angle randomized over a spread so we have more of a "spray"
var angle = this.velocity.rad() + spread - (Math.random() * spread * 2);
// The magnitude of the emitter's velocity
var magnitude = this.velocity.length();
// New velocity based off of the calculated angle and magnitude
var velocity = Vector.fromAngle(angle, magnitude);
// return our new Particle
return new Particle(this.position.clone(), velocity);
}

1. Application state modiﬁed and rendered independently.
2. Expensive mutations performed as little as possible.
3. Physics based animations.

We're getting there. You can do this now, sort of.

var Greets = React.createClass({
getInitialState: function() {
return { name: "Portland" };
},
render: function() {
return <div>Hello {this.state.name}</div>;
}
});

The virtual DOM is an abstraction that saves you the cost of
expensive render-based mutation in a familiar package.
It's better, but a virtual DOM is not our application state.

While you're exploring JavaScript, explore graphics & games.
Go, do neat things with canvas!

Maybe you'll ﬁnd a use for normal mapped backgrounds.
http://jsoverson.github.io/texture.js/demo/bricks.html

Or maybe you'll use it to understand the bounds of an optical illusion.
http://jsoverson.github.io/concentric-circle-illusion/

Or maybe you'll make some really awesome games.
https://ga.me/games/polycraft (turbulenz.com)

Or maybe you'll try…
phaser.io

Graphics Programming for Web Developers

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