Webgl para JavaScripters

WebGL para JavaScripters

Luz Caballero

Luz Caballero - @gerbille

Web Opener

Agenda
• Que es WebGL?
• Para qué se puede usar?
• Cómo funciona?
• Lo que hay que saber para empezar
• Un poco de código

<canvas id=‘c’ width=‘100’ height=‘100’></canvas>

document.getElementById(‘c’).getContext(‘webgl’)

• Visualización de datos

• Creative coding

• Arte

• Environments de diseño 3D

• Videos de música

• Graﬁcación de funciones matemáticas

• Modelado de objectos y espacios 3D

• Creación de texturas

• Simulaciones físicas

• ...procesamiento rápido de cualquier tipo de
datos

graﬁcación de funciones matemáticas

modelado de objetos y espacios 3D

JavaScript

WebGL JS API

GPU (Compiled Program)

JavaScript

WebGL JS API

GLSL API Vertex Shader

GLSL API Fragment Shader

Lo que hay que saber
para empezar

The 3D scene

image source: http://computer.yourdictionary.com/graphics

Choosing a library
• Three.js
• PhiloGL
• GLGE
• J3D
• TDL
• ...

<!DOCTYPE html>
<html>
  <head>
  <title>Learning WebGL lesson 11 in PhiloGL</title>
  <link href="path/to/file.css" type="text/css" rel="stylesheet"
media="screen" />
  <script src="path/to/PhiloGL.js"></script>
  <script src="path/to/index.js"></script>
  </head>

  <body onload="webGLStart();">
  <canvas id="lesson11-canvas" width="500" height="500"></canvas>
  
  </body>
</html>

function webGLStart() {
  var pos, $ = function(d) { return document.getElementById(d); };

  //Create moon
  var moon = new PhiloGL.O3D.Sphere({
  nlat: 30,
  nlong: 30,
  radius: 2,
  textures: 'moon.gif'
  });

//Create application
  PhiloGL('lesson11-canvas', {
  camera: {
  position: {
  x: 0, y: 0, z: -7
  }
  },
  textures: {
  src: ['moon.gif'],
  parameters: [{
  name: 'TEXTURE_MAG_FILTER',
  value: 'LINEAR'
  }, {
  name: 'TEXTURE_MIN_FILTER',
  value: 'LINEAR_MIPMAP_NEAREST',
  generateMipmap: true
  }]
  },
  events: {
  onDragStart: function(e) {
  pos = {
  x: e.x,
  y: e.y
  };
  },
  onDragMove: function(e) {
  var z = this.camera.position.z,
  sign = Math.abs(z) / z;

  moon.rotation.y += -(pos.x - e.x) / 100;
  moon.rotation.x += sign * (pos.y - e.y) / 100;
  moon.update();
  pos.x = e.x;
  pos.y = e.y;
  },
  onMouseWheel: function(e) {
  e.stop();
  var camera = this.camera;
  camera.position.z += e.wheel;
  camera.update();
  }
  },

onError: function() {
  alert("There was an error creating the app.");
  },
  onLoad: function(app) {
  //Unpack app properties
  var gl = app.gl,
  program = app.program,
  scene = app.scene,
  canvas = app.canvas,
  camera = app.camera;

  //get light config from forms
  lighting = $('lighting'),
  ambient = {
  r: $('ambientR'),
  g: $('ambientG'),
  b: $('ambientB')
  },
  direction = {
  x: $('lightDirectionX'),
  y: $('lightDirectionY'),
  z: $('lightDirectionZ'),

  r: $('directionalR'),
  g: $('directionalG'),
  b: $('directionalB')
  };
  //Basic gl setup
  gl.clearColor(0.0, 0.0, 0.0, 1.0);
  gl.clearDepth(1.0);
  gl.enable(gl.DEPTH_TEST);
  gl.depthFunc(gl.LEQUAL);
  gl.viewport(0, 0, canvas.width, canvas.height);

//Add object to the scene
  scene.add(moon);

  //Draw the scene
  draw();

  function draw() {
  //clear the screen
  gl.clear(gl.COLOR_BUFFER_BIT | gl.DEPTH_BUFFER_BIT);
  //Setup lighting
  var lights = scene.config.lights;
  lights.enable = lighting.checked;
  lights.ambient = {
  r: +ambient.r.value,
  g: +ambient.g.value,
  b: +ambient.b.value
  };
  lights.directional = {
  color: {
  r: +direction.r.value,
  g: +direction.g.value,
  b: +direction.b.value
  },
  direction: {
  x: +direction.x.value,
  y: +direction.y.value,
  z: +direction.z.value
  }
  };

  //render moon
  scene.render();
  //Animate
  Fx.requestAnimationFrame(draw);
  }
  }
  });
}

function init() {
  container = document.createElement( 'div' );
  document.body.appendChild( container );

  // camera
  camera = new THREE.PerspectiveCamera( 75, SCREEN_WIDTH / SCREEN_HEIGHT, 1, 100000 );
  camera.position.z = 75;

  // scene
  scene = new THREE.Scene();

  // lights
  var ambient = new THREE.AmbientLight( 0xffffff );
  scene.add( ambient );

  // more lights
  var directionalLight = new THREE.DirectionalLight( 0xffeedd );
  directionalLight.position.set( 0, -70, 100 ).normalize();
  scene.add( directionalLight );
}

// renderer
webglRenderer = new THREE.WebGLRenderer();
webglRenderer.setSize( SCREEN_WIDTH, SCREEN_HEIGHT );
webglRenderer.domElement.style.position = "relative";
container.appendChild( webglRenderer.domElement );

// loader
var loader = new THREE.JSONLoader(),
loader.load( { model: "obj/church/church.js", callback: createScene } );

function createScene( geometry ) {
  zmesh = new THREE.Mesh( geometry, new THREE.MeshFaceMaterial() );
  zmesh.position.set( 0, 16, 0 );
  zmesh.scale.set( 1, 1, 1 );
  scene.add( zmesh );
}

function onDocumentMouseMove(event) {
  mouseX = ( event.clientX - windowHalfX );
  mouseY = ( event.clientY - windowHalfY );
}

function animate() {
  requestAnimationFrame( animate );
  render();
}

function render() {
  zmesh.rotation.set(-mouseY/500 + 1, -mouseX/200, 0);
  webglRenderer.render( scene, camera );
}
</script>

Resources
• An Introduction to WebGL @ dev.Opera
• PhiloGL
• PhiloGL tutorial
• WebGL w/o a library @ dev.Opera
• Porting 3D models to WebGL @ dev.Opera
• News and resources @ the Learning WebGL blog
• WebGL w/o a library @ Learning WebGL
• Three.js
• Three.js tutorial
• WebGL FAQ
• The Khronos WebGL forum
• WebGL-dev mailing list

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