Demos
Test 1	Test 2	Test 3	Test 4	Test 5

The above links lead off to a few basic physics demos, using the Phys2D library as an engine.

Incorporating Phys2D into JavaFX was done by creating a brand new (experimental) library to augment standard scene graph nodes; making them physics-aware. Then a special kind of scene container was created that would model the physical world simulation and manage the physics of any nodes it contained.

First I created a mixin called PhysicalNode, acting as a base class for common physics properties added to scene graph nodes. Then I subclassed each required shape to create a physical alternative (eg: PhysicalRectangle, PhysicalCircle, PhysicalImageView...)

Next I created a new Scene subclass with the ability to handle either standard or physical scene graph nodes, animating them as necessary as per their properties. The new PhysicalScene allows things like gravity to be set, and relationships between its physical child nodes to be defined using joints. It also provides a JavaFX Script friendly event mechanism for notifying any PhysicalNodes of collisions.

Where necessary coordinate systems etc. were translated to fit with current JFX nodes (so PhysicalRectangle has its origin in the top left corner as per JFX, not at its centre as Phys2D prefers).

To create a scene using the library, PhysicalNodes are added to a PhysicalScene just like regular JFX nodes. Two extra steps are required, however:

• Fixed/springy/angled/etc. joints may be defined to connect nodes, if required.
• A start() function needs to be called on the scene to kick off the physics engine updates. Update: This will now be kicked off automatically via the postinit block of the PhysicalScene, unless autoStart is set to false.

Apart from that physical nodes are used pretty much like their regular non-physical counterparts. Updates from the physical model are automatically fed to the node's layoutX, layoutY, rotate, etc; and manipulating a node's fields directly (like setting layoutX) merely requires a call to the node's updatePhysical() function to keep the physical model in step.