For breaking API changes see this document.

New Functionality

Soft Body

• Added soft body skinning constraints. This can be used to limit the movement of soft body vertices based on a skinned mesh. See documentation for more info or watch this movie.
• Added ability to turn on/off skinning constraints and to update the max distance for all constraints with a distance multiplier.
• Added dihedral bend constraints for soft bodies. See movie.
• Added long range attachment constraints (also called tethers) for soft bodies.
• Added SoftBodyContactListener which allows you to get callbacks for collisions between soft bodies and rigid bodies. See movie.
• Added support for a vertex radius for soft bodies. This keeps the vertices a fixed distance away from the surface which can be used to avoid z-fighting while rendering the soft body.
• Added SoftBodySharedSettings::CreateConstraints function that can automatically generate constraints based on the faces of the soft body.
• Added ability to update a soft body outside of the physics simulation step using SoftBodyMotionProperties::CustomUpdate. This is e.g. useful if the soft body is teleported and needs to 'settle'.

Vehicles

• Added support for less than 1 collision test per simulation step for vehicle wheels. This behavior can be configured differently when the vehicle is active / inactive. This can be used for LODding vehicles.
• Added wheel index to VehicleConstraint::CombineFunction friction callback and calculating longitudinal and lateral friction in the same call so you can have more differentiation between wheels.
• Added ability to override the max tire impulse calculations for wheeled vehicles. See WheeledVehicleController::SetTireMaxImpulseCallback.
• Added ability to disable the lean steering limit for the motorcycle, turning this off makes the motorcycle more unstable, but gives you more control over the final steering angle.

Character

• CharacterVirtual will now receive an OnContactAdded callback when it collides with a sensor (but will have no further interaction).
• Added user data to CharacterVirtual.

Constraints

• Swing limits do not need to be symmetrical anymore for SixDOFConstraints. This requires using the new pyramid shaped swing limits (ESwingType::Pyramid). SwingTwistConstraints still requires symmetrical limits but can use the pyramid swing limits too. These are cheaper to evaluate but are less smooth.
• Twist limits no longer need to be centered around zero for SixDOFConstraints and SwingTwistConstraints, any value between -PI and PI is supported now.
• Changed the meaning of Constraint::mNumVelocity/PositionStepsOverride. Before the number of steps would be the maximum of all constraints and the default value, now an overridden value of 0 means that the constraint uses the default value, otherwise it will use the value as specified. This means that if all constraints in an island have a lower value than the default, we will now use the lower value instead of the default. This allows simulating an island at a lower precision than the default.
• Bodies can now also override the default number of solver iterations. This value is used when the body collides with another body and a contact constraint is created (for constraints, the constraint override is always used).
• Added fraction hint to PathConstraintPath::GetClosestPoint. This can be used to speed up the search along the curve and to disambiguate fractions in case a path reaches the same point multiple times (i.e. a figure-8).
• Added Constraint::ResetWarmStart and Ragdoll::ResetWarmStart. Used to notify the system that the configuration of the bodies and/or constraint has changed enough so that the warm start impulses should not be applied the next frame. You can use this function for example when repositioning a ragdoll through Ragdoll::SetPose in such a way that the orientation of the bodies completely changes so that the previous frame impulses are no longer a good approximation of what the impulses will be in the next frame.
• Multithreading the SetupVelocityConstraints job. This was causing a bottleneck in the case that there are a lot of constraints but very few possible collisions.

Collision Detection

• Created an object layer filter implementation that is similar to Bullet's group & mask filtering, see ObjectLayerPairFilterMask.
• Created implementations of BroadPhaseLayerInterface, ObjectVsBroadPhaseLayerFilter and ObjectLayerPairFilter that use a bit table internally. These make it easier to define ObjectLayers and with which object layers they collide.
• Renamed SensorDetectsStatic to CollideKinematicVsNonDynamic and made it work for non-sensors. This means that kinematic bodies can now get collision callbacks when they collide with other static / kinematic objects.
• Added function to query the bounding box of all bodies in the physics system, see PhysicsSystem::GetBounds.

Simulation

• Implemented enhanced internal edge removal algorithm. This should help reduce ghost collisions. See BodyCreationSettings::mEnhancedInternalEdgeRemoval and movie.
• Added BodyInterface::SetUseManifoldReduction which will clear the contact cache and ensure that you get consistent contact callbacks in case the body that you're changing already has contacts.

Various

• Ability to enable gyroscopic forces on bodies to create the Dzhanibekov effect.
• Supporting SIMD for WASM build. Use -msimd128 -msse4.2 options with emscripten to enable this.
• Allowing WASM build to use a custom memory allocator.
• Added DebugRendererSimple which can be used to simplify the creation of your own DebugRenderer implementation. It only requires a DrawLine, DrawTriangle and DrawText3D function to be implemented (which can be left empty).
• Added ability to update the height field materials after creation.

Removed functionality

• Ability to restrict rotational degrees of freedom in local space, instead this is now done in world space.

Bug fixes

• Fixed a bug in cast sphere vs triangle that could return a false positive hit against a degenerate triangle.
• Fixed bug in soft body vs tapered capsule. The calculations were slightly off causing a normal on the top or bottom sphere to be returned while the tapered part was actually closest.
• Fixed bug where colliding a cyclinder against a large triangle could return an incorrect contact point.
• Fixed bug where soft bodies would collide with sensors as if they were normal bodies.
• Sensors will no longer use speculative contacts, so will no longer report contacts before an actual contact is detected.
• Hinge limit constraint forces were clamped wrongly when the hinge was exactly at the minimum limit, making it harder to push the hinge towards the maximum limit.
• Fixed bug when a body with limited DOFs collides with static. If the resulting contact had an infinite effective mass, we would divide by zero and crash.
• Fixed unit tests failing when compiling for 32-bit Linux. The compiler defaults to using x87 instructions in this case which does not work well with the collision detection pipeline. Now defaulting to the SSE instructions.
• Fixed assert and improved interaction between a fast moving rigid body of quality LinearCast and a soft body.
• When creating a MeshShape with triangles that have near identical positions it was possible that the degenerate check decided that a triangle was not degenerate while the triangle in fact would be degenerate after vertex quantization. The simulation would crash when colliding with this triangle.
• A scaled compound shape with a center of mass of non zero would not apply the correct transform to its sub shapes when colliding with a soft body
• A soft body without any edges would hang the solver
• Fixed GCC 11.4 warning in JobSystemThreadPool.cpp: output may be truncated copying 15 bytes from a string of length 63
• Longitudinal friction impulse for wheeled/tracked vehicles could become much higher than the calculated max because each iteration it was clamped to the max friction impulse which meant the total friction impulse could be PhysicsSettings::mNumVelocitySteps times too high.
• Properly initializing current engine RPM to min RPM for wheeled/tracked vehicles. When min RPM was lower than the default min RPM the engine would not start at min RPM.
• Fixed a possible division by zero in Body::GetBodyCreationSettings when the inverse inertia diagonal had 0's.
• When specifying a -1 for min/max distance of a distance constraint and the calculated distance is incompatible with the other limit, we'll clamp it to that value now instead of ending up with min > max.
• Fixed bug that contact cache was partially uninitialized when colliding two objects with inv mass override of 0. When the contact listener would report a non zero inv mass override the next simulation step this would mean that the simulation would read garbage and potentially crash due to NaNs.