WebGL allows for 3D graphics rendering within web browsers using JavaScript and standard web technologies. It provides an API for accessing a computer's GPU similarly to Canvas for 2D drawing. THREE.js makes WebGL programming easier by abstracting away complexities like shader programming and matrix computations. A simple example creates a 3D cube in THREE.js with just a few lines of code versus the longer WebGL example. THREE.js provides high-level objects for cameras, lights, materials and more to build 3D scenes efficiently in the browser.

1. WebGL with THREE.js
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2. @antonnarusberg
anton@cannedapps.com
Google Developers Group Tallinn
http://bit.ly/gdgtallinn
@GDGTallinn
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3. 3D in Web Browsers
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4. 3D in Web Browsers
Full power of computer's GPU using only JS, web browser
and standard web technology stack.
Old way - plugins, native applications
New way - WebGL
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5. Browser compatibility
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6. So how do you use it?
WebGL is an API, accessed through
JavaScript programming interfaces.
Analogous to 2D drawing using the
HTML5 Canvas element
Based on OpenGL ES 2.0 standard
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7. An (overly) simplified Example:
Cube with plain WebGL
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8. // get the WebGL context to access the API
var canvas = document.getElementById("lesson04-canvas");
gl = canvas.getContext("experimental-webgl");
// Set up Shaders
var fragmentShader = getShader(gl, "shader-fs");
var vertexShader = getShader(gl, "shader-vs");
shaderProgram = gl.createProgram();
gl.attachShader(shaderProgram, vertexShader);
gl.attachShader(shaderProgram, fragmentShader);
gl.linkProgram(shaderProgram);
gl.useProgram(shaderProgram);
// ....
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9. <script id="shader-fs" type="x-shader/x-fragment">
precision mediump float;
varying vec4 vColor;
void main(void) {
gl_FragColor = vColor;
}
</script>
<script id="shader-vs" type="x-shader/x-vertex">
attribute vec3 aVertexPosition;
attribute vec4 aVertexColor;
uniform mat4 uMVMatrix;
uniform mat4 uPMatrix;
varying vec4 vColor;
void main(void) {
gl_Position = uPMatrix * uMVMatrix * vec4(aVertexPosition, 1.0);
vColor = aVertexColor;
}
</script>
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10. // A taste of creating the array of vertices for the cube
cubeVertexPositionBuffer = gl.createBuffer();
gl.bindBuffer(gl.ARRAY_BUFFER, cubeVertexPositionBuffer);
vertices = [
// Front face
-1.0, -1.0, 1.0, 1.0, -1.0, 1.0, 1.0, 1.0, 1.0, -1.0, 1.0, 1.0,
// Back face
-1.0, -1.0, -1.0, -1.0, 1.0, -1.0, 1.0, 1.0, -1.0, 1.0, -1.0, -1.0,
// Top face
-1.0, 1.0, -1.0, -1.0, 1.0, 1.0, 1.0, 1.0, 1.0, 1.0, 1.0, -1.0,
// Bottom face
-1.0, -1.0, -1.0, 1.0, -1.0, -1.0, 1.0, -1.0, 1.0, -1.0, -1.0, 1.0,
// Right face
1.0, -1.0, -1.0, 1.0, 1.0, -1.0, 1.0, 1.0, 1.0, 1.0, -1.0, 1.0,
// Left face
-1.0, -1.0, -1.0, -1.0, -1.0, 1.0, -1.0, 1.0, 1.0, -1.0, 1.0, -1.0
];
gl.bufferData(gl.ARRAY_BUFFER, new Float32Array(vertices), gl.STATIC_DRAW);
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11. // Rotating the cube with Matrix computations
function drawScene() {
mat4.translate(mvMatrix, [3.0, 0.0, 0.0]);
mat4.rotate(mvMatrix, degToRad(rCube), [1, 1, 1]);
gl.uniformMatrix4fv(shaderProgram.mvMatrixUniform, false, mvMatrix);
// ... Bind buffers etc.
gl.drawElements(gl.TRIANGLES, cubeVertexIndexBuffer.numItems,
gl.UNSIGNED_SHORT, 0);
// ...
}
function tick() {
requestAnimFrame(tick);
rCube += 1;
drawScene();
}
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12. Skills needed for plain WebGL
* GLSL, the shading language used by OpenGL and
WebGL
* Lots of Math for Matrix computation to set up
transformations
* Creating Vertex buffers to hold data about vertex
positions, normals, colors, and textures
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13. THREE.js to the rescue!
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14. THREE.js
* Abstracts away all the painful overhead
* Elegant API to create and manipulate Cameras,
Objects, Lights, Materials etc.
* THREE.js is Open Source
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15. A Cube example using THREE.js
http://learningthreejs.com/data/
lets_do_a_cube/docs/lets_do_a_cube.html
Jerome Etienne - great tutorials on THREE.js
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16. // Set up a Camera
camera = new THREE.Camera(70, window.innerWidth / window.innerHeight, 1,
1000);
camera.position.y = 150;
camera.position.z = 350;
camera.target.position.y = 150;
// Create a Scene
scene = new THREE.Scene();
// Create a Cube
material = new THREE.MeshNormalMaterial();
cube = new THREE.Mesh( new THREE.CubeGeometry( 200, 200, 200 ), material);
cube.position.y = 150;
// Add the Cube to the Scene
scene.addObject( cube );
// Boilerplate
renderer = new THREE.WebGLRenderer();
renderer.setSize( window.innerWidth, window.innerHeight );
$(“#container”).appendChild( renderer.domElement );
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17. function animate() {
render();
// Loop
requestAnimationFrame( animate );
}
function render() {
// Rotate
cube.rotation.x += 0.02;
cube.rotation.y += 0.0225;
cube.rotation.z += 0.0175;
// Bounce
var dtime = Date.now() - startTime;
cube.scale.x = 1.0 + 0.3*Math.sin(dtime/300);
cube.scale.y = 1.0 + 0.3*Math.sin(dtime/300);
cube.scale.z = 1.0 + 0.3*Math.sin(dtime/300);
renderer.render( scene, camera );
}
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18. It’s alive!
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19. More Features
Renderers
WebGL, <canvas>, <svg>
Cameras
Perspective and orthographic; controllers: trackball, FPS, path and more
Lights
Ambient, direction, point, spot and hemisphere lights. Cast and receive shadows
Materials
Lambert, Phong and more - with textures, smooth-shading
Shaders
Access to full WebGL capabilities like lens flare, depth pass and an extensive post-processing library
Objects
meshes, particles, sprites, lines, ribbons, ...
Geometry
plane, cube, sphere, torus, 3D text and more
Export/Import
utilities to create Three.js-compatible JSON files from: Blender, CTM, FBX, 3D Max, and OBJ
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20. http://threejs.org/
https://github.com/mrdoob/three.js
http://learningthreejs.com
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21. Thank you!
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