Introduction to Three.js
Hey there! If you're reading this, you're probably interested in learning how to use Three.js, the JavaScript library for creating 3D graphics on the web.
Three.js is a powerful tool that allows you to create stunning 3D graphics like this one in the left side of your screen with just a few lines of code. Whether you're a seasoned web developer or a complete beginner, Three.js is an excellent choice for creating interactive 3D graphics that run smoothly in any modern web browser.
Setting Up Your Development Environment
Before we dive into the world of Three.js, let's make sure you have everything you need to get started.
First and foremost, you'll need a web browser. Any modern browser will do, I personally recommend Firefox as is generally considered to be the best choice for web development due to its powerful developer tools and is also really light-weighted.
Next, you'll need a text editor. There are many options to choose from, but some popular choices include Notepad++, Sublime Text, and VS Studio.
Finally, you'll need a local server to run your Three.js code. There are many ways to set up a local server, but the easiest option is to use a tool like XAMPP or MAMP, which allows you to run a server on your local machine with just a few clicks.
Getting Started with Three.js
Now that you have everything you need to get started, let's dive into some code!
The first thing you'll need to do is download the Three.js library from the Three.js website. Once you have the library downloaded, you can include it in your HTML file like this:
<script src="/path/to/three.js"></script>
With the library included, you're ready to start creating some 3D graphics!
Creating a Scene
In Three.js, everything is drawn inside a "scene". Think of a scene as a canvas on which you can draw 3D objects.
To create a scene, you'll need to create a THREE.Scene object and store it in a variable:
const scene = new THREE.Scene();
Adding a Camera
Now that you have a scene, you'll need a way to view it. In Three.js, you can use a "camera" to do this.
To create a perspective camera, you'll need to create a THREE.PerspectiveCamera object and store it in a variable. The perspective camera takes three arguments: the field of view, the aspect ratio, and the near and far clipping planes. The field of view is the angle of the camera's view in degrees, the aspect ratio is the width of the camera's view divided by its height, and the near and far clipping planes define the distances at which objects are no longer visible. Here's an example of how you can create a perspective camera:
const camera = new THREE.PerspectiveCamera(75, window.innerWidth /
window.innerHeight, 0.1, 1000);
With a camera created, you can position it in the scene using the camera.position.set() method. This method takes three arguments: the x, y, and z coordinates of the camera. You can also use the camera.lookAt() method to specify the point in the scene that the camera should be looking at. Here's an example of how you can position and orient the camera:
camera.position.set(0, 0, 5);
camera.lookAt(0, 0, 0);
Rendering the Scene
With a scene and a camera created, you're ready to start rendering the scene to the screen. To do this, you'll need to create a "renderer" that takes the scene and camera as input and generates an image of the scene from the perspective of the camera. There are several types of renderers you can use in Three.js, but the most common is the THREE.WebGLRenderer, which uses the WebGL graphics API to render the scene.
To create a WebGL renderer, you'll need to create a THREE.WebGLRenderer object and store it in a variable. The renderer takes a few optional arguments, such as the width and height of the renderer, the color of the background, and whether or not to enable antialiasing. Here's an example of how you can create a WebGL renderer:
const renderer = new THREE.WebGLRenderer({ antialias: true });
renderer.setSize(window.innerWidth, window.innerHeight);
renderer.setClearColor(0xffffff);
With a renderer created, you can use the renderer.render() method to render the scene to the screen. This method takes the scene and the camera as arguments and generates an image of the scene from the perspective of the camera. You can then use the renderer.domElement property to get the renderer's canvas element and append it to the document:
renderer.render(scene, camera);
document.body.appendChild(renderer.domElement);
You can also use the requestAnimationFrame() function to continuously render the scene at a specified frame rate. This function takes a callback function that is called on each frame, and you can use it to update the scene and render it again. Here's an example of how you can use requestAnimationFrame() to continuously render the scene:
function animate() {
requestAnimationFrame(animate);
// Update the scene
renderer.render(scene, camera);
}
animate();
Adding 3D Objects
Now that you have a scene, a camera, and a renderer set up, you're ready to start adding some 3D objects to the scene. There are many types of 3D objects you can create in Three.js, such as spheres, cubes, and meshes. In this tutorial, we'll focus on creating a simple cube.
To create a cube, you'll need to create a THREE.BoxGeometry object and store it in a variable. The box geometry takes three arguments: the width, height, and depth of the cube. You'll also need to create a THREE.MeshBasicMaterial object and store it in a variable. This material is a simple, flat material that can be used to color the cube. Finally, you'll need to create a THREE.Mesh object and store it in a variable. This object combines the geometry and material into a single entity that can be added to the scene. Here's an example of how you can create a cube:
const geometry = new THREE.BoxGeometry(1, 1, 1);
const material = new THREE.MeshBasicMaterial({ color: 0x00ff00 });
const cube = new THREE.Mesh(geometry, material);
With a cube created, you can add it to the scene using the scene.add() method. This method takes the cube as an argument and adds it to the scene. Here's an example of how you can add the cube to the scene:
scene.add(cube);
With the cube added to the scene, it will be rendered to the screen on each frame. You can also use the cube.position.set() method to position the cube in the scene, and the cube.rotation.set() method to rotate it. These methods take the x, y, and z coordinates or rotations as arguments. Here's an example of how you can position and rotate the cube:
cube.position.set(1, 1, 1);
cube.rotation.set(0.5, 0.5, 0.5);
Conclusion
In this tutorial, you learned the basics of Three.js and how to create a simple 3D scene with a cube. With the knowledge you gained in this tutorial, you're ready to start building more complex 3D applications with Three.js.
I hope you enjoyed this tutorial and happy coding!