The creator of PhysicsJS made a tutorial on how to create this game, but using the 0.5 version. I saw making it work using 0.7 as an opportunity to better learn the engine. The main changes were:
- world.publish() became world.emit()
- world.emit() has a different syntax now. See API documentation.
- world.subscribe() became world.on()
- The images are no longer available to download, so create your own.
- Earth made static so it would not move when crashed into.
- Layers have been added to the canvas renderer so offset is accessed differently. The automatically generated layer's id is 'main.'
- Old code created vectorish class object and called vector functions on it. Used scratchpad service instead.