If every particle or area of particles had its own gravity, that would be way better for many simulations, and would open up the path for new ones. But--- Gravity depends on mass and distance, so if there was a scale feature put in (the advanced gravity would only work with this), then it would be more versatile and would not break saves. By scale feature, I mean a little text box saying- "One pixel = __cm?" Or maybe m or Km.
Meaning that the particles in a certain area (a square) would all be moved in the same direction at the same time. This would mean way less calculations.
@billion57: I second this notion. And for those with older computers, why not just make it another option in the Simulation Options screen? It could be something like Particle Gravitation. It would help for making solar system simulations.
What Powdertoy do you play? They already have Powered GPMP - Its called GPMP.... use PSCN to Activate and NSCN to deactivate. Use Heat to heat it and increase its gravity, and Cool to cool and decreases its gravity....
This actually might not be too hard, in the gravity update code when it checks for BHOL/WHOL (maybe not how it works, I haven't looked at it yet), just add gravity for all particles instead of only those. It would really only work well with fftw enabled, because with that, gravity is basically instant, even on a full screen (still a lot of lag though). Without it, by the time gravity was updated, the particles would have moved far away. It isn't enabled in the normal tpt, it would have to be enabled first (the bug with older computers was fixed, there's no reason not to)