LiquidFun Programmer's Guide
Limitations

LiquidFun uses several approximations to simulate rigid body physics efficiently. This brings some limitations.

Here are the current limitations:

  1. Stacking heavy bodies on top of much lighter bodies is not stable. Stability degrades as the mass ratio passes 10:1.
  2. Chains of bodies connected by joints may stretch if a lighter body is supporting a heavier body. For example, a wrecking ball connect to a chain of light weight bodies may not be stable. Stability degrades as the mass ratio passes 10:1.
  3. There is typically around 0.5cm of slop in shape versus shape collision.
  4. Continuous collision does not handle joints. So you may see joint stretching on fast moving objects.
  5. LiquidFun uses the symplectic Euler integration scheme. It does not reproduce parabolic motion of projectiles and has only first-order accuracy. However it is fast and has good stability.
  6. LiquidFun uses an iterative solver to provide real-time performance. You will not get precisely rigid collisions or pixel perfect accuracy. Increasing the iterations will improve accuracy.

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