If you love playing games with a controller, you might wonder how you can create your own web games that support gamepad input. Thanks to the HTML5 Gamepad API, you can access the state and events of any connected gamepad device from your browser. In this article, you will learn how to use the HTML5 Gamepad API to create gamepad-enabled web games.
The HTML5 Gamepad API is a specification that defines a JavaScript interface for accessing and responding to gamepad devices. It allows you to detect if a gamepad is connected or disconnected, read the buttons and axes values, and listen to gamepad events. The HTML5 Gamepad API is supported by most modern browsers, except Internet Explorer and Safari.
The Gamepad API is a technology that allows us to access the state of connected gamepad devices & we can interact using it on our application using JavaScript. Like we can check if any gamepad device is connected or not, we can check which buttons are clicked by listening to the events of the connected gamepad. So it provides an interface for interaction between Web Apps & Gamepad devices.
To access the gamepad devices, you need to use the navigator.getGamepads() method, which returns an array of gamepad objects. Each gamepad object has properties such as id, index, connected, mapping, buttons, and axes. You can use these properties to identify and interact with the gamepad devices. For example, you can use the id property to check the name and vendor of the gamepad, or the buttons property to get an array of button objects with pressed and value attributes.
So first we should check if the browser supports the Gamepad API & if it supports we can get the Gamepad array of objects like, if(!!navigator.getGamepads){ // Browser supports the Gamepad API var gamepads = navigator.getGamepads(); // it returns, GamepadList {0: Gamepad, 1: Gamepad, 2: undefined, 3: undefined} } else { alert('Your browser does not support Gamepad API'); } If I try to check the Gamepad object like, var gamepad = navigator.getGamepads()[0]; It will contain values like, { axes: Array[4] buttons: Array[16] connected: true id: "Xbox 360 Controller (XInput STANDARD GAMEPAD)" index: 0 mapping: "standard" timestamp: 12 }
To handle gamepad events, you need to use the window.addEventListener() method, which registers a callback function to be executed when a specific event occurs. There are two types of gamepad events: gamepadconnected and gamepaddisconnected. These events fire when a gamepad is plugged in or unplugged from the computer. The event object has a property called gamepad, which is a gamepad object that represents the connected or disconnected device. For example, you can use the gamepadconnected event to display a message when a gamepad is detected, or the gamepaddisconnected event to remove the gamepad from the game logic.
There are some common Gamepad API events like, window.addEventListener("gamepadconnected", function(e) { // Gamepad connected console.log("Gamepad connected", e.gamepad); }); window.addEventListener("gamepaddisconnected", function(e) { // Gamepad disconnected console.log("Gamepad disconnected", e.gamepad); }); window.addEventListener("gamepadbuttondown", function(e){ // Button down console.log( "Button down", e.button, // Index of button in buttons array e.gamepad ); }); window.addEventListener("gamepadbuttonup", function(e){ // Button up console.log( "Button up", e.button, // Index of button in buttons array e.gamepad ); });
To read the gamepad state, you need to use a loop that calls the navigator.getGamepads() method repeatedly and updates the game logic accordingly. You can use the requestAnimationFrame() method, which tells the browser to run a function before the next repaint. This way, you can ensure that your game runs smoothly and responds to the gamepad input in real time. For example, you can use the requestAnimationFrame() method to check the buttons and axes values of the gamepad and move a character on the screen.
To map the gamepad buttons and axes, you need to use the mapping property of the gamepad object, which indicates how the buttons and axes are mapped to a standard layout. There are two possible values for the mapping property: standard and empty. The standard value means that the gamepad follows a common mapping scheme, where the buttons and axes are assigned to specific indices. The empty value means that the gamepad has an unknown mapping scheme, where the buttons and axes are not mapped to any standard layout. For example, you can use the mapping property to determine how to interpret the gamepad input and assign different actions to different buttons and axes.
To test and debug the gamepad input, you need to use the browser's developer tools, which provide various features and tools to inspect and modify the web page. You can use the console, which is a panel that displays messages and errors, and allows you to execute JavaScript commands. You can use the console.log() method, which prints a message to the console, to display the gamepad objects and properties. You can also use the debugger, which is a tool that lets you pause and resume the execution of the code, and inspect the variables and functions. You can use the debugger to set breakpoints, which are points where the code stops running, and step through the code line by line. For example, you can use the debugger to check if the gamepad events are firing correctly, or if the game logic is working as expected.