TagAndEngine

Introduction to AndEngine – Getting the code

In this series I will tell you how to use one of my favorite Android 2D Game Engines, AndEngine. We will go step by step through the processes, starting at simply getting the code, continuing with drawing sprites, using cameras, physics and so on.

AndEngine was started by Nicolas Gramlich as part of his Bachelor’s thesis in the beginning of 2010. It is an engine that provides lots of powerful features while hiding more advanced things like Open GL calls from the developer. It provides lots of extensions like a  Robotium extension, a Box2D extension, which is mostly written and maintained by badlogicgames‘ Mario Zechner for his libGDX-project, a SVG extension or a TMX tiled maps extension.

It has been used in various featured games like Greedy Spiders, Noogra Nuts or Zynga’s Dream Zoo.

Let’s get started.

 

Getting the code

At the very beginning you’ll need to download the most recent version of AndEngine. To do that, open your console, go to the directory of your choice and do a git clone of the engine by typing

git clone git://github.com/nicolasgramlich/AndEngine.git

That’s all. You now have a powerful game engine, ready to be used on your computer or mobile device.

Now here’s a story: When AndEngine was written, the author had to make a choice: did he want to write lots of useful code or lots of useful documentation? He chose the more fun part and that’s why AndEngine provides little to no documentation, which is one of its most frequent points of criticism. However, the source is all open, you can read it, change it, do whatever you like with it. There are the AndEngine forums and Nicolas tries to write the code in a way that it’s documenting itself.

In order to provide the developers an idea of what AndEngine can do, the AndEngine samples were created. You can get them by also cloning the git repository:

git clone git://github.com/nicolasgramlich/AndEngineExamples.git

As you can now see there are a lot of dependencies to the different extensions. Go ahead and clone them:

git clone git://github.com/nicolasgramlich/AndEngineAugmentedRealityExtension.git
git clone git://github.com/nicolasgramlich/AndEngineLiveWallpaperExtension.git
git clone git://github.com/nicolasgramlich/AndEngineMODPlayerExtension.git
git clone https://github.com/nicolasgramlich/AndEngineMultiplayerExtension
git clone https://github.com/nicolasgramlich/AndEnginePhysicsBox2DExtension
git clone https://github.com/nicolasgramlich/AndEngineSVGTextureRegionExtension
git clone https://github.com/nicolasgramlich/AndEngineTexturePackerExtension
git clone https://github.com/nicolasgramlich/AndEngineTMXTiledMapExtension

Now you have a lot of code. Import them into your IDE of choice. Your workspace should now look something like this:

Let’s start a look at the examples. Connect your device or start an emulator with GPU emulation and run the AndEngineExamples on it.

AndEngine physics example

AndEngine physics example

What you will find is an overview over AndEngine’s many features.

There are two important branches of AndEngine: The GLES2-branch and the GLES2-AnchorCenter branch. Since the latter will become the main branch soon, it is recommended to pull its code too. To do so, just go into each of your AndEngine-projects using your shell and execute

git pull origin GLES2-AnchorCenter

You might want to switch to this branch now by executing

git checkout -b GLES2-AnchorCenter origin/GLES2-AnchorCenter

Now take your time to play, take a look into the code and look forward to the next part of this series in which we will go through the basic parts of the engine.

 

If you are having problems compiling any of AndEngine’s code or issues cloning the repositories, please post a comment.

The AndEngine PhysicsEditor Extension

[Update] Now supports circle sprites. Also, Andreas Löw, the creator of PhysicsEditor will link to it with the next update of the editor. [/Update]

If you ever created a physics game, for example with my favorite game engine, AndEngine, and wanted to produce a polygonal body, you probably did something that sucked big time. Something like defining your vertices in code. This is

  1. Dirty
  2. Really painful
This is why we looked around and found the PhysicsEditor, a simple to use tool to create an output that describes physic definitions. While iOS integration seemed to work both from the editor into the code, it only provided an AndEngine Exporter-format, but no tool to integrate it back into the engine.
Until today.

 

Capabilities

Here is what it’s capable of:
  • Definitions of (multiple) bodies
  • Definitions of (multiple) fixtures
  • Definitions of polygon shapes
  • Definitions of circle shapes
  • Definition of density, friction and elasticity
  • Definition of dynamic and non-dynamic bodies
  • Definition of sensor and non-sensor fixtures
  • Collision filtering
  • Automatic setting of a body’s user data

 

How to use it

For this part I assume you already know the very basics of AndEngine development. Let’s start from the beginning.

First, download the PhysicsEditor. Open it and import your sprite of choice. I chose the star from the examples project:

Now, draw your physical representation. You might want to use the Shape tracer for that (the wand icon):Now make your settings on the right

and push ‘publish as’. Save your XML somewhere.

Next, it’s time to get the source. Clone the repository using something like git clone git://github.com/ANDLABS-Git/AndEngine-PhysicsEditor-Extension.git. Import the source. Now, make sure you also have the AndEngine and the AndEnginePhysicsBox2DExtension in your workspace. You may have to update this dependencies.

A good match: PhysicsEditor Extension, Box2D Extension, AndEngine and PhysicsEditor Examples

A good match: PhysicsEditor Extension, Box2D Extension, AndEngine and PhysicsEditor Examples

Now in your project, create a new PhysicsEditorLoader-object using the default constructor:
final PhysicsEditorLoader loader = new PhysicsEditorLoader();
Use it to load whatever you want:

try {
loader.load(this, mPhysicsWorld, "xml/", "star.xml", star, true, true);
} catch (IOException e) {
//...
}

The parameters provided are a Context, the PhysicsWorld you want to attach your body to, the base path, the path to your specific definition, the IAreaShape (for example a Sprite) you want your definition to be connected to, whether you want your object’s position to be updated and whether you want your object’s rotation to be updated. And that’s it.

There are some other use cases covered like drawing lines for debugging or loading multiple definitions, but that’s not more than about five keystrokes of additional work. You can take a look at the examples to see what I mean (in case you are curious).
It is possible to use the PhysicsEditor as a tool for level creation. In fact, it enables you to actually ‘draw’ your levels in your graphics tool of choice. Please keep in mind though that the maximum size of an IAreaShape in AndEngine is 2048 pixels, so you may want to use multiple sprites to achieve big levels. Also, memory is low on mobile devices, depending which device your are targeting, you maybe want to think about using a different method than this.

 

A ball jumping on a polygonal physical representation

A ball jumping on a polygonal physical representation

Please keep in mind that this is a very early release that may still contain some bugs and needs some refactoring. Please feel free to leave any issue you discover in the project’s issue tracker.

So far, we have tested the four sample projects on the following devices:

  • Samsung Galaxy Y (2.3.6)
  • Nexus One (2.3.6)
  • Galaxy Nexus (4.0.4)

Wanted: Beta Tester

ANDLABS will soon release a new, terrific 2D game for the Android platform (of course). For this game, we need beta testers. I can’t tell you much about the content, but four things are for sure:

  • It’s an absolutely new concept
  • If you like tower defense games, you will love it
  • If you like physics games, you will love it
  • The beta test will start in the period of mid to end of August.

So if you are interested: Good choice! Just leave your e-mail-adress in the comments (I will delete it before approving your comment).

Thank you very much, I’m convinced you will like this game.

Edit: already 10 sign ups here plus two on G+. You guys are great!

Phantastic Game: Gravity Wins

A couple of weeks, we brought a new great product to the Android Market: Gravity Wins.

Gravity Wins is the well known 4 in a row game, with one major enhancement: Every x rounds, the game board makes a 90° twist. This causes you to think ahead in a completely different way.

Try it, you will love it.

Here are some screenshots:

The game board

The game board

The gravity twist

The gravity twist

 

And here is a video review made by playandroid.com:

As always: Please feel free to leave comments and tell us what you like.

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