I needed to develop a 3D interface for simulating a two player version of PacMan. I also enjoy experimenting with different tools for game development, and so I decided to look into developing 3D applications for the web.
Modern browsers have evolved drastically. Browsers were initially only capable of rendering HTML and submitting forms, they were later enhanced to enable developers to load parts of the page asynchronously. The demand for more interactive applications on the web grew and led to the development and use of browser plugins like Flash. With the demand for interactive applications and compatibility on different platforms like mobile devices, browsers needed something native to allow developers the freedom to develop applications across many platforms. This is the creation of <canvas>.
The canvas element in HTML is simply an element that allows drawing of shapes on the page.
To accommodate different drawing needs, the canvas provides two different contexts:
The 2D context allows for drawing simple shapes in a step by step manner. Drawing shapes involves setting the brush properties before drawing a specific shape. The 2D context makes it easy to draw text, lines, arcs, rectangles, etc.
The 3D context is in the form of the WebGL API. WebGL allows for drawing any 3D geometry from any perspective or point of view. This allows for more complex shapes and geometries to be drawn.
Most modern browsers as well as their mobile version counterparts support WebGL. These include, Google Chrome, Safari, Firefox, Opera, and even latest versions of Internet Explorer. This is great for diverse distribution of your application.
WebGL leverages off the GPU (Graphics Processing Unit) for hardware acceleration. GPUs are geared towards graphics calculations and rendering. The aim is to calculate and render complex graphics as efficiently as possible – this is not a job for the CPU.
What’s in the box?
3D rendering consists of two main concepts, the Vertex Shader, and the Fragment Shader. This might sound complicated, but in essence:
- The Vertex Shader is a position calculator. It handles the mathematics and calculations for converting points so that they are positioned correctly.
- The Fragment Shader is a colour chooser. It determines what colour different elements in the 3D space should be.
Coding with Raw WebGL
WebGL is a API and has brought amazing capabilities to modern browsers. As with any raw 3D development, there are some pains.
- WebGL has many settings and configurations. One needs to understand what settings are required, how they are used, and what the correct setting should be. These are typically settings and configurations for the Vertex Shader and Fragment Shader.
- Rendering simple 3D shapes with WebGL can be cumbersome due to the amount of code required. WebGL expects the developer to provide all the vertices of geometries (Creating a cube involves approximately 112 lines of code). Developing and debugging this can potentially be a nightmare.
- Too much plumbing and mathematics, not enough fun. We all want to see our ideas come to life, and not be bogged down by details.
When starting out with using a new technology, learning a new language, or building any project in general, it’s good to have a basic template to work from. Usually the template will take care of any settings that the project requires to run, managing dependencies, managing builds, etc.
Bower is a dependency management tool, it allows for dependencies to be imported and included in a project automatically. With bower, there is no need to download 3rd party dependencies manually.
Setting Up a Three.js Project
The following commands will work on any UNIX system.
npm install -g yo
Install the Three.js generator
npm install -g generator-threejs
Make a new directory for your project
Navigate to your new project directory
Generate a Three.js project with Yeoman
Deploy your project with Grunt
3D – THREE.JS
With raw WebGL, it takes around 112 lines of code to create a simple cube. Three.js allows for this to be done in a single line of code.
There are a few concepts related to Three.js and 3D Programming in general that should be understood before embarking on a project.
The scene is a container for 3D objects. The scene will hold everything that is in the 3D world. This includes any object in the 3D world.
The camera is an object that cannot be seen be the user. The scene is displayed to the user from the perspective of the camera.
Controls could be mouse, keyboard, touch events, gamepads, etc. Controls can be used to move and manipulate the camera or any other object in the scene.
Objects are 3D entities in the scene. These can be something as simple as a cube, to something as complex as 3D humanoids, vehicles, buildings, etc. It’s great that we can create objects, but what are they made up of?
- Object Geometry: The geometry is the shape of the object. This includes all the points that make up the object as well as their positions relative to each other.
- Object Texture: The texture is typically an image that that is overlaid over the geometry. It gives the shape any aesthetics and any effects that is required. It is the skin for the geometry.
The renderer is responsible for assembling the scene and it’s objects, and displaying it to the user from the perspective of the camera.
Physics – Cannon.js
When developing 3D applications, more often than not, there is a requirement for physics, gravity, or collision detection.
It is tedious and difficult to write custom collision detection and physics code, again, we want more fun and less mathematics and plumbing.
Cannon.js is a useful API that is compatible with Three.js for physics. Cannon allows developers to bind to existing Three.js 3D objects and perform physics calculations and manipulations on them.This is useful for simulating gravity and creating worlds where collisions actually result in an effect instead of objects overlaying each other.
Uses and Advantages
- Great for game development.
- Interactive applications.
- Write once, run almost anywhere.
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