Release v0.18.0

[sebcrozet]

v0.18.0 (24 Jan. 2024)

The main highlight of this release is the implementation of a new non-linear constraints solver for better stability
and increased convergence rates. See #579 for additional information.

In order to adjust the number of iterations of the new solver, simply adjust IntegrationParameters::num_solver_iterations.
If recovering the old solver behavior is useful to you, call IntegrationParameters::switch_to_standard_pgs_solver().

It is now possible to specify some additional solver iteration for specific rigid-bodies (and everything interacting
with it directly or indirectly through contacts and joints): RigidBodyBuilder::additional_solver_iterations and
RigidBodyBuilder::set_additional_solver_iterations. This allows for higher-accuracy on subsets of the physics scene
without affecting performance of the other parts of the simulation.

Fix

• Fix bug causing angular joint limits and motor to sometimes only take into account half of the angles specified by the user.
• Fix bug where collisions would not be re-computed after a collider was re-enabled.
• Fix incorrect update of angular degrees-of-freedoms on spherical multibody joints.
• Fix debug-renderer showing moved kinematic rigid-bodies only at their initial position.

Added

• Add a SpringJoint and SpringJointBuilder for simulating springs with customizable stiffness and damping coefficients.
• Add SphericalJoint::local_frame1/2, ::set_local_frame1/2, and SphericalJointBuilder::local_frame1/2 to set both
  the joint’s anchor and reference orientation.
• Add EffectiveCharacterMovement::is_sliding_down_slope to indicate if the character controlled by the kinematic
  character controller is sliding on a slope that is too steep.
• Add Wheel::side_friction_stiffness to customize the side friction applied to the vehicle controller’s wheel.
• Add Wheel::raycast_info to access more wheel information relative to the ground.
• Add DebugRenderStyle::disabled_color_multiplier to make the debug-renderer color disabled object differently.

Modified

• Make Wheel::friction_slip public to customize the front friction applied to the vehicle controller’s wheels.
• Add the DebugRenderBackend::filter_object predicate that can be implemented to apply custom filtering rules
  on the objects being rendered.
• Switch the testbed to bevy 0.12 and use its new Gizmos API for rendering lines.
• Rename NarrowPhase::contacts_with to NarrowPhase::contact_pairs_with.
• Rename NarrowPhase::intersections_with to NarrowPhase::intersection_pairs_with.