Box2D tutorial topics

• Introduction
• Setting up (Linux)
• Setting up (Windows)
• Setting up (Mac OSX)
• Testbed structure
• Making a test
• Bodies
• Fixtures
• World settings
• Forces and impulses
• Custom gravity
• Moving at constant speed
• Rotating to a given angle
• Jumping
• Using debug draw
• Drawing your own objects
• User data
• Anatomy of a collision
• Collision callbacks
• Collision filtering
• Sensors
• Ray casting
• World querying
• Removing bodies safely
• The 'can I jump' question
• Ghost vertices
• Joints - overview
• Joints - revolute
• Joints - prismatic

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• FAQ / gotchas

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• Tutorial source code

Advanced topics

• Conveyor belts
• Projected trajectory
• Sticky projectiles
• Hovercar suspension
• Top-down car physics
• One-way walls
• Buoyancy
• Explosions
• Physics-driven particles

Other topics

• Setting up (iPhone)

Chinese version -> 中文

Building the testbed (Mac OSX)

Let's look at the process of setting up the default 'testbed' which is part of the Box2d source code base. The testbed is a very useful tool which contains examples of various features which you can interact with using the mouse, adjust parameters, pause and step the simulation etc.

The simplest way to build the Box2D library is to use the cmake file which is included in the source code download. For this you will need the cmake tool, which you can download from here, and XCode which you can download from Apple's developer site (developer.apple.com) after you have registered. When installing cmake be sure to choose the 'Install command line links' option so you can use the tool in a terminal. Since we'll be using cmake, all we really need for compiling is the gcc compiler itself, but apparently it is not distributed as a single tool so you'll need to get the whole XCode package (somebody let me know if I'm wrong about that). XCode is also available on the Snow Leopard DVD if you have one.

After installing XCode and cmake, download the Box2D source code archive from here. The rest of the process is the same as for linux:

unzip Box2D_v2.1.2.zip
cd Box2D_v2.1.2/Box2D/Build
cmake ..
make

After this you should see that some new folders have been created, one of which is 'Testbed' and this in turn contains an executable file called 'Testbed', so the app can be started like this:

cd Testbed
./Testbed

You should see the testbed window showing like this:
Select from the drop-down list in the top right to try out the tests that are currently in the testbed. We will be adding our own items into this list later on.

Testbed features

Apart from the obvious features visible in the right hand control panel, the testbed also allows you to:

• Move the view around - arrow keys or drag with right mouse button
• Zoom the view - z,x keys
• Grab objects in the scene - left mouse button
• Launch a bomb into the scene from a random location - space bar
• Launch a bullet into the scene - drag left mouse button while holding shift, then let go

Depending on which test you view, you can sometimes use the keyboard to interact with the scene too. We will make use of the mouse and keyboard interactions in these tutorials.

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