Fast recalculation of gravity equipotential lines after Planet explosion

Dear all,

I have to find a fast way to compute changes in the equipotential lines as the
result of sudden changes in the local gravitational fields (2D space).
(Caused by the destruction of a planet for example). I could recalculate
everything but it takes too much time for the device on which the
calculation is deployed. The environment has lots of bodies, so an
analytical solution is not to consider.

I compute the level lines, picking a initial point and iterating along the gradient of the gravitational force.

I don't really know where to start, but I'm thinking about a local
method that only propagates changes on a limited range around the
"explosion". If you want to take a look at the origin of the problem,
here is a screenshot of the project, and the link to the related (free) iphone
game.

I was also thinking about representing the equipotential lines as Bezier lines and only updating a couple of points instead of redrawing complete exact lines but then I'm not sure 2 lines won't cross eachother since they are interpolated.

Thanks for you help, any idea is welcomed !

Seb

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Edited June 23, 201312 yr by imatfaal
removal of commercial link