Gravity breaks revolute joint's angle limits

[exoexo-dev]

In 3D in a chain of multiple dynamic bodies connected via revolute joints with specified angle limits (in a setup similar to crates/avian3d/examples/chain_3d.rs where the first body kinematic), the bodies that "carry" other bodies connected to them break out of their joint's limits.

For example, in a setup with 10 bodies and angle limit set to a const PI / 4.0 (same in min and max) this happens:

When the gravity is switched off the bodies settle in a circle as expected (note that 2 bodies are overlapping here):

Changing the density of the bodies doesn't seem to have any effect, but change in gravity does. In here it's increased from the first screenshot, which forces the bodies break out further out of their limits:

edit: all the joints have compliance set to 0.0

[exoexo-dev]

My temporary hacky workaround is to multiply correction calculated in fn apply_angle_limits by some constant > 1 so that it "overpowers" the gravity