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Seo Master present to you:
By Dominic Szablewski, creator of the Impact Game Engine

This post is part of Who's at Google I/O, a series of guest blog posts written by developers who are appearing in the Developer Sandbox at Google I/O.


Impact is a JavaScript game engine that uses the HTML5 Canvas and Audio elements for graphics and sound, instead of relying on any browser plugins. Impact's main focus is on classic 2D games. Examples include the Biolab Disaster Jump'n'Run game and the Z-Type Space Shooter. These games, like many other 2D games, draw sprites in front of multiple background layers.


Each background layer is drawn from a tileset, an image containing all the individual building blocks, and a tilemap, a 2D array that tells the renderer where to draw each of these tiles. Similarly, sprites are drawn from an animation sheet, an image with all the animation's frames.

This technique has proven so efficient and flexible that it was enforced in hardware on early game consoles: the Super Nintendo could not do anything other than draw tiled background maps and sprites. There was no way to directly access single pixels on the screen.

The HTML5 Canvas element is perfectly equipped for these kinds of games. Most importantly, the Canvas API's drawImage() method allows us to draw only a certain part of a tileset or animation sheet to the screen. In Impact, however, you don't have to deal with any of the Canvas API methods directly. Instead, you specify your tilemaps and animation sheets and let the engine handle the details.

This is how you'd create an animation from an animation sheet:

// Each animation frame is 16x16 pixels
var sheet = new ig.AnimationSheet( 'player.png', 16, 16 );

// This creates the "run" animation: it has 6 frames (the 2nd row 
// in the image), with each one being shown for 0.07 seconds
var run = new ig.Animation( sheet, 0.07, [6,7,8,9,10,11] );

Similarly, here's the code needed to create and draw a background layer:

// Create a 2D tilemap
var map = [
 [5, 3, 4],
 [2, 7, 1],
 [6, 0, 3]
];

// Specify a layer with a tilesize of 16px and our tilemap
var layer = new ig.BackgroundMap( 16, map, 'tileset.png' );
layer.draw();

You don't have to create these tilemaps by hand. Impact comes with a powerful level editor called Weltmeister, which makes it easy to draw background layers and position your entities (non-static objects in the game world) in your levels.


When drawing on a Canvas, the performance is mostly bounded by the number of draw calls. It is far more efficient to draw one or two very large images than to draw several hundred small ones. This means that drawing background layers tile by tile can be quite slow, especially on mobile devices.

The Impact engine therefore has a special "pre-render" mode that you can enable on background layers. This mode will first draw the tilemap into large chunks of 512x512 pixels when loading a level, and then use these chunks to fill the screen instead of drawing the layer tile by tile. With this technique, you can get good frame rates even for fast-paced games on Android and iOS devices.

Impact also handles sound, input, timing, and much more for you. It's by no means a game engine that can do everything – and it doesn't try to be one – but it's very good at the things it can do.


Come see Impact in the Developer Sandbox at Google I/O on May 10-11.

Dominic Szablewski is the creator of the Impact Game Engine. He recently finished his Bachelor Thesis about HTML5 Gaming and now lives the dream by selling Impact and making games.

Posted by Scott Knaster, Editor

2013, By: Seo Master

Seo Master present to you:
By Vic Gundotra, Senior Vice President of Engineering

Cross-posted on the Official Google Blog.

In less than 24 hours, we’ll be kicking off Google I/O 2011, our annual developer conference here in San Francisco. With more than 5,000 participants from 60 countries, including 110 sessions, 261 speakers and 152 Sandbox partners, this year’s I/O will be the biggest one yet.

This year’s keynote presentations will highlight the biggest opportunities for developers and feature two of our most popular and important developer platforms: Android and Chrome. Google engineers from Andy Rubin and Sundar Pichai’s teams will unveil new features, preview upcoming updates, and provide new insights into the growing momentum behind these platforms.

Plus, for the first time in Google I/O history, you’ll be able to join us throughout the two days at I/O Live. We’ll live stream the two keynote presentations, two full days of Android and Chrome technical sessions, and the After Hours party. Recorded videos from all sessions across eight product tracks will be available within 24 hours after the conference. Whether you’ll be joining us in San Francisco or from the farthest corner of the world, bookmark www.google.com/io and check back on May 10 at 9:00 a.m. PDT for a fun treat as we count down to 00:00:00:00.


If you’re attending the conference this year, we can’t wait to meet with you and share our vision for the future of web and mobile development. If you aren’t able to make it this year, you can continue to follow us on the Google Code Blog and on Twitter (#io2011) over the next two days as we share photos, videos, news, and recaps of the event. It’s going to be an exciting 48 hours!


Vic Gundotra is Senior Vice President of Engineering and oversees Google's developer efforts, including Google I/O.

Posted by Scott Knaster, Editor

2013, By: Seo Master

Seo Master present to you: 2013, By: Seo Master