WebGL With Three.js – Lesson 4

By | May 31, 2014
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WebGL With Three.js – Lesson 4

Today we continue our lessons for those who study webgl, and today we will show you how to add 3D text on the scene, how to extrude two-dimensional shapes, we also will consider how to load ready 3D models into the scene using the OBJLoader. It seems to be a difficult process, but it is not – the code for loading 3D models is fairly simple.

The result of our lesson is as follows:

HTML

Two new libraries were added into the html: font1.js and OBJLoader.js

<!DOCTYPE html>
<html lang="en" >
    <head>
        <meta charset="utf-8" />
        <meta name="author" content="Script Tutorials" />
        <title>WebGL With Three.js - Lesson 4 | Script Tutorials</title>
        <meta name="viewport" content="width=device-width, initial-scale=1.0, maximum-scale=1.0, user-scalable=no">
        <link href="css/main.css" rel="stylesheet" type="text/css" />
    </head>
    <body>
        <script src="js/three.min.js"></script>
        <script src="js/THREEx.WindowResize.js"></script>
        <script src="js/OrbitControls.js"></script>
        <script src="js/fonts/font1.js"></script>
        <script src="js/OBJLoader.js"></script>
        <script src="js/stats.min.js"></script>
        <script src="js/script.js"></script>
    </body>
</html>

Javascript

First, we create a simple (empty) scene (scene, camera, renderer, controls, light and ground):

// load texture
var texture = THREE.ImageUtils.loadTexture('texture.png');
texture.repeat.set(0.03, 0.03);
texture.wrapS = texture.wrapT = THREE.RepeatWrapping;
texture.anisotropy = 16;
texture.needsUpdate = true;

var lesson4 = {
    scene: null,
    camera: null,
    renderer: null,
    container: null,
    controls: null,
    clock: null,
    stats: null,

    init: function() { // Initialization

        // create main scene
        this.scene = new THREE.Scene();

        var SCREEN_WIDTH = window.innerWidth,
            SCREEN_HEIGHT = window.innerHeight;

        // prepare camera
        var VIEW_ANGLE = 45, ASPECT = SCREEN_WIDTH / SCREEN_HEIGHT, NEAR = 1, FAR = 10000;
        this.camera = new THREE.PerspectiveCamera( VIEW_ANGLE, ASPECT, NEAR, FAR);
        this.scene.add(this.camera);
        this.camera.position.set(0, 400, 800);
        this.camera.lookAt(new THREE.Vector3(0,0,0));

        // prepare renderer
        this.renderer = new THREE.WebGLRenderer({antialias:true, alpha: false});
        this.renderer.setSize(SCREEN_WIDTH, SCREEN_HEIGHT);
        this.renderer.setClearColor(0xffffff);

        this.renderer.shadowMapEnabled = true;
        this.renderer.shadowMapSoft = true;

        // prepare container
        this.container = document.createElement('div');
        document.body.appendChild(this.container);
        this.container.appendChild(this.renderer.domElement);

        // events
        THREEx.WindowResize(this.renderer, this.camera);

        // prepare controls (OrbitControls)
        this.controls = new THREE.OrbitControls(this.camera, this.renderer.domElement);
        this.controls.target = new THREE.Vector3(0, 0, 0);

        // prepare clock
        this.clock = new THREE.Clock();

        // prepare stats
        this.stats = new Stats();
        this.stats.domElement.style.position = 'absolute';
        this.stats.domElement.style.bottom = '0px';
        this.stats.domElement.style.zIndex = 10;
        this.container.appendChild( this.stats.domElement );

        // add directional light
        var dLight = new THREE.DirectionalLight(0xffffff);
        dLight.position.set(0, 1000, 0);
        dLight.castShadow = true;
        // dLight.shadowCameraVisible = true;
        this.scene.add(dLight);

        // add simple ground
        var groundGeometry = new THREE.PlaneGeometry(1000, 1000, 1, 1);
        ground = new THREE.Mesh(groundGeometry, new THREE.MeshLambertMaterial({
            color: 0x4489FE, side: THREE.DoubleSide
        }));
        ground.position.y = -20;
        ground.rotation.x = - Math.PI / 2;
        ground.receiveShadow = true;
        this.scene.add(ground);

    },
};

// Animate the scene
function animate() {
    requestAnimationFrame(animate);
    render();
    update();
}

// Update controls and stats
function update() {
    lesson4.controls.update(lesson4.clock.getDelta());
    lesson4.stats.update();
}

// Render the scene
function render() {
    if (lesson4.renderer) {
        lesson4.renderer.render(lesson4.scene, lesson4.camera);
    }
}

// Initialize lesson on page load
function initializeLesson() {
    lesson4.init();
    animate();
}

if (window.addEventListener)
    window.addEventListener('load', initializeLesson, false);
else if (window.attachEvent)
    window.attachEvent('onload', initializeLesson);
else window.onload = initializeLesson;

3D text

The best way to display text in 3D enviromnemt is to use a ready 3D font (for Three.js). In general, there are many websites where you can download fonts, however we need special javascript fonts (typefaced fonts). This website may help you to convert custom fonts into javascript fonts (upload your font, hit the ‘convert’, and then follow the steps until it let you download the result). However, at the time of writing this tutorial, this service was not available, so I had to use ready-made fonts to create our demonstration. To draw a three-dimensional text I prepared the following function:

draw3dText: function(x, y, z, text) {

    // prepare text geometry
    var textGeometry = new THREE.TextGeometry(text, {
        size: 60, // Font size
        height: 20, // Font height (depth)
        font: 'droid serif', // Font family
        weight: 'bold', // Font weight
        style: 'normal', // Font style
        curveSegments: 1, // Amount of curve segments
        bevelThickness: 5, // Bevel thickness
        bevelSize: 5, // Bevel size
        bevelEnabled: true, // Enable/Disable the bevel
        material: 0, // Main material
        extrudeMaterial: 1 // Side (extrude) material
    });

    // prepare two materials
    var materialFront = new THREE.MeshPhongMaterial({ map: texture, color: 0xffff00, emissive: 0x888888 });
    var materialSide = new THREE.MeshPhongMaterial({ map: texture, color: 0xff00ff, emissive: 0x444444 });

    // create mesh object
    var textMaterial = new THREE.MeshFaceMaterial([ materialFront, materialSide ]);
    var textMesh = new THREE.Mesh(textGeometry, textMaterial);
    textMesh.castShadow = true;

    // place the mesh in the certain position, rotate it and add to the scene
    textMesh.position.set(x, y, z);
    textMesh.rotation.x = -0.3;
    this.scene.add(textMesh);
}

Two different materials are used to different sides of the text (for the front and side).

ExtrudeGeometry

This class allows us to create three-dimensional extruded geometry from two-dimensional path shape. I drew the boat for our today’s demonstration:

drawCustomObject: function(x, y, z) {

    // prepare points for custom shape (ship)
    var objectPoints = [
        new THREE.Vector2 (275, 265),
        new THREE.Vector2 (205, 240),
        new THREE.Vector2 (125, 220),
        new THREE.Vector2 (274, 115),
        new THREE.Vector2 (275, 85),
        new THREE.Vector2 (330, 85),
        new THREE.Vector2 (310, 100),
        new THREE.Vector2 (330, 115),
        new THREE.Vector2 (275, 115),
        new THREE.Vector2 (274, 266),
        new THREE.Vector2 (305, 266),
        new THREE.Vector2 (305, 240),
        new THREE.Vector2 (360, 240),
        new THREE.Vector2 (360, 285),
        new THREE.Vector2 (340, 335),
        new THREE.Vector2 (215, 335),
        new THREE.Vector2 (175, 320),
        new THREE.Vector2 (150, 290),
        new THREE.Vector2 (75, 230),
        new THREE.Vector2 (200, 264),
        new THREE.Vector2 (274, 264),
    ];

    // prepare shape
    var objectShape = new THREE.Shape(objectPoints);

    var extrusionSettings = {
        amount: 20,
        curveSegments: 1, // Amount of curve segments
        bevelThickness: 5, // Bevel thickness
        bevelSize: 5, // Bevel size
        bevelEnabled: true, // Enable/Disable the bevel
        material: 0, // Main material
        extrudeMaterial: 1 // Side (extrude) material
    };

    // prepare ship geometry
    var objectGeometry = new THREE.ExtrudeGeometry( objectShape, extrusionSettings );

    // prepare two materials
    var materialFront = new THREE.MeshPhongMaterial({ map: texture, color: 0xffff00, emissive: 0x888888 });
    var materialSide = new THREE.MeshPhongMaterial({ map: texture, color: 0xff00ff, emissive: 0x444444 });

    // create mesh object of the ship
    var objectMaterial = new THREE.MeshFaceMaterial([ materialFront, materialSide ]);
    var objectMesh = new THREE.Mesh( objectGeometry, objectMaterial );
    objectMesh.castShadow = true;

    // place the object in the certain position, rotate it and add to the scene
    objectMesh.position.set(x, y, z);
    objectMesh.rotation.x = Math.PI;
    this.scene.add(objectMesh);
}

OBJLoader

I left the most interesting for the end – loading ready OBJ models. The fact that there are a huge number of ready three-dimensional objects (at various websites) that you can add into your scene, and three.js gives us this opportunity through the use of the OBJLoader class:

loadObjFile: function(x, y, z) {

    // prepare new OBJLoader and load the 'legoBrick.obj' model
    var loader = new THREE.OBJLoader();
    loader.load('legoBrick.obj', function(object) {

        // apply custom material for all children
        var legoMat = new THREE.MeshLambertMaterial({ color: 0x008800 });
        object.traverse( function (child) {
            if (child instanceof THREE.Mesh) {
                child.material = legoMat;
                child.material.needsUpdate = true;
            }
        });

        // place the object in the certain position, rotate, scale and add to the scene
        object.position.x = x;
        object.position.y = y;
        object.position.z = z;
        object.rotation.y = Math.PI/2;
        object.scale.set(40, 40, 40);
        lesson4.scene.add(object);
    });
}

To import the model we just specify the address to this model, as well as the callback function. In this function we applied the custom material for it’s children.

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