Outlines for making high-particle-count real-time toy simulation

[magwo]

• Screw barnes-hut. Too much memory thrashing for modern architectures (I'm making this up).
• Off-load N-body simulation to a web worker, and:
  • Use a very compact linear memory structure, probably typed arrays for positions ,velocities, mass, all mashed into one big array with named indices for access.
  • Find out the most efficient memory order in which to do direct N-body. Maybe even duplication for increased memory linearity?
  • Split simulation into near/far interactions. Probably only two levels to avoid memory usage.
• Keep a rich-object copy of all the N bodies in the non-web-worker code, and:
  • Update positions, velocities and accelerations when web worker outputs them
  • Extrapolate form position, velocity, accelerations, and:
    • Soft-snap to new correct position when available
  • Handle visual-effects-only particles particles, let them gravitate toward the N bodies (using very soft Plummer model?). Should probably also use near/far update intervals, or simply use sqr distance threshold).
• Probably use Plummer model for gravity