Learning Three.js

or WebGL for Dummies

Let's Make a 3D Game: Keyboard

This post is the first of a series Let’s Make a 3d game. The series will walk you down the path of game developement. It will describe the various parts of a web game: input handling, map generation, collision, physics, sounds, graphics etc… Obviously we will glue them to make an actual game. Quite a bit of work but im super excited !

It will be a marble game. Not sure which kind yet, but they are many. I did pacmaze, a pacman in 3D and buddymaze, a multi-player first personn shooter. But this one gonna be from scratch, thus we will discover things as together :)

We will try to code each part of the game to be as reusable as possible. The first part will be the keyboard handling. It isnt the hardest, nor the most important, but it is super simple. Perfect to get us started.

Let’s get started

In a game, a keyboard handler is a bit special. Usually this is done with events , e.g. jQuery.bind() or hotkeys. But we are doing a game and all games revolve around a game loop. So the keyboard must be queryable at any time during this loop, as opposed to event-driven. Our code should keep tracks of which key and which modifier is pressed. Let’s call it KeyboardState.

Let’s include the script

You download it from here and include it in your page like this

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<script src='THREEx.KeyboardState.js'></script>

How to use it ?

Now that the script is included, create a keyboard variable like this.

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var keyboard = new THREEx.KeyboardState();

After that you can query the current status of the keyboard with .pressed("W"). For example if you want shift+H to display help, do the following.

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if( keyboard.pressed("shift+H") )     displayHelp();

If you ever want to stop listening to the keyboard, just use this line

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keyboard.destroy()

Conclusion

For more details on THREEx.KeyboardState, see its annoted source. We have seen it is quite simple to use. Ok now we got the keyboard handling for our game. Nice but it seems a bit virtual for now. But i think the game will become more concret when we gonna have stuff moving on the screen.

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