Optional fxNode’s fixed x-position (if position was fixed)
Optional fyNode’s fixed y-position (if position was fixed)
Optional indexNode’s zero-based index into nodes array. This property is set during the initialization process of a simulation.
Optional vxNode’s current x-velocity
Optional vyNode’s current y-velocity
Optional xNode’s current x-position
Optional yNode’s current y-position
The base data structure for the datum of a Simulation Node. The optional properties contained in this data structure are internally assigned by the Simulation upon (re-)initialization.
When defining a data type to use for node data, it should be an extension of this interface and respect the already "earmarked" properties used by the simulation.
IMPORTANT: Prior to initialization, the following properties are optional: index, x, y, vx, and vy. After initialization they will be defined. The optional properties fx and fy are ONLY defined, if the node's position has been fixed.