Chapter 7. Writing a Game for the Motion-Sensing Game Controller • 124

we read its width. In the next line we do the same to determine the block’s height. Because all blocks have the same width and height, we have to do this only once. After that we determine the ball’s current position.

In line 38, we use the each method to loop over all blocks in the HTML document. each expects a callback function that gets called for each block. Note that the function doesn’t get any arguments, because you can find the current block in $(this).

In the loop function, we check whether the current block is visible, because if it’s not, we don’t have to check it for a collision. We use our helper functions inXRange and inYRange to see whether the current block has been hit by the ball. In that case we make it invisible, and depending on the way the ball has hit the block, we invert the ball’s velocities.

Finally, we have to make sure that the gameLoop function is called every 30 milliseconds to make the game run smoothly:

BrowserGame/Arduinoid/js/arduinoid.js $(function() {

initGame(); setInterval(gameLoop, 30);

});

We use yet another variant of jQuery’s $ function. This time we pass it an anonymous function that gets called as soon as the HTML page has been loaded completely. In this function, we initialize the game and make sure the gameLoop function is called every 30 milliseconds.

The game is complete, so play a few rounds and relax! You deserve it!

What If It Doesn’t Work?

If you cannot make this chapter’s code run, you should download the code from the book’s website and try to run it. Make sure you’re using the right serial port in the arduinoid.js and game_controller.js files in the code/BrowserGame/Arduinoid/js/ directory.

Exercises

•Create your own computer mouse using the ADXL335 accelerometer. It should work in free air, and it should emit the current acceleration around the x- and y-axes. It should also have a left button and a right button. Write a Chrome app (or perhaps code in a programming language of your choice?) to control a mouse pointer on the screen.

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Exercises • 125

Creating Games and Game Controllers with the Arduino

If you’re thinking about a proper case for the game controller you’ve built in the preceding chapter, you might have a look at the Lego/Arduino controller.a Its innards differ from the controller we’ve built, but its case is really cool.

You can use the Arduino to build more than your own cool game controllers. You can also use it to build some cool games. With the right extension shields, you can even turn an Arduino into a powerful gaming console. The most powerful extension shields are probably the Gameduinob and its successor, Gameduino 2.c

If you don’t need color graphics and stereo sound, you can find even cheaper solutions, such as the Video Game Shieldd or the Hackvision.e They generate a monochrome video signal, and you can learn how to do it yourself in Chapter 8, Generating Video Signals with an Arduino, on page 127.

While looking for a solution that doesn’t need an external monitor, someone built a Super Mario Bros. clone with minimal hardware requirements.f It’s a perfect example of the unbelievable creativity that the Arduino sets free.

a.http://strangemeadowlarkprojects.blogspot.de/2014/05/a-legoarduino-game-controller.html

b.http://excamera.com/sphinx/gameduino/

c.http://excamera.com/sphinx/gameduino2/index.html#gameduino2

d.http://www.wayneandlayne.com/projects/video-game-shield/

e.http://nootropicdesign.com/store/index.php?main_page=index&cPath=2

f.http://blog.makezine.com/archive/2010/03/super-mario-brothers-with-an-arduin.html

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