Any run-time code that traversed the transform hierarchy of physics objects to find other entities must instead store references to entity IDs of interest through a different mechanism.
Baking of non-uniform scale for parametric PhysicsShape types has changed to more predictably approximate skewed render meshes. Double check the results on any non-uniformly scaled objects in your projects.
Angular Velocity is currently set in Motion Space. The Motion Space orientation of dynamic bodies may have changed with the changes to the conversion pipeline. If dynamic bodies are now rotating differently, check the values of Initial Angular Velocity in the PhysicsBody component, or values set to Angular in the PhysicsVelocity component.
Convex PhysicsShape objects with no custom mesh assigned now include points from enabled mesh renderers on their children. Double check any convex objects in your projects.
The RaycastInput and ColliderCastInput structs have changed. See below for details.
Changes
Run-Time API
Renamed CollisionFilter.CategoryBits to CollisionFilter.BelongsTo.
Renamed CollisionFilter.MaskBits to CollisionFilter.CollidesWith.
RaycastInput and ColliderCastInput have changed:
At the input level, start and end positions are now specified rather then an initial position and a displacement.
Start replaces Position.
End replaces Direction which had been confusing as it was actually a displacement vector to a second point on the ray.
Ray has been made internal as a lower level interface and updated to be less ambiguous.
Added job interfaces for easier reading of simulation events, instead of having to work directly with block streams.
ICollisionEventsJob calls Execute() for every collision event produced by the solver.
ITriggerEventsJob calls Execute() for every trigger event produced by the solver.
These events now also include the Entity's involved, not just the rigid body indices.
Added job interfaces for easier modification of simulation data, instead of having to work directly with block streams.
IBodyPairsJob calls Execute() for every body pair produced by the broad phase.
IContactsJob calls Execute() for every contact manifold produced by the narrowphase.
IJacobiansJob calls Execute() for every contact jacobian before it is solved.
Authoring/Conversion API
Renamed SecondPassLegacyRigidbodyConversionSystem to LegacyRigidbodyConversionSystem.
Deprecated FirstPassPhysicsBodyConversionSystem.
Renamed SecondPassPhysicsBodyConversionSystem to PhysicsBodyConversionSystem.
Deprecated overload of PhysicsShape.GetCapsuleProperties() returning raw points.
Deprecated overload of PhysicsShape.GetPlaneProperties() returning raw points.
Renamed PhysicsShape.FitToGeometry() to PhysicsShape.FitToEnabledRenderMeshes(). New method accounts for enabled MeshRenderer components on child objects with the same physics body and leaf shape.
PhysicsShape.GetConvexHullProperties() now includes points from enabled MeshRenderer components on child objects with the same physics body and leaf shape when no custom mesh has been assigned.
Run-Time Behavior
Added a fixed angle constraint to prismatic joints so they no longer rotate freely.
Any Entity with a PhysicsVelocity component will be added to the PhysicsWorld and integrated, even if it has no PhysicsCollider.
Authoring/Conversion Behavior
Physics data on deactivated objects in the hierarchy are no longer converted.
All physics objects (i.e. bodies) are now un-parented (required since all simulation happens in world space).
Legacy Collider components are no longer converted if they are disabled.
Converted PhysicsShape objects with non-uniform scale now bake more predictable results when their Transform is skewed.
All menu paths for custom assets and authoring components have changed from 'DOTS Physics' to 'DOTS/Physics'.
Fixes
Fixed trigger events not being raised between kinematic-vs-kinematic or kinematic-vs-static body pairs.
Fixed crash in BuildPhysicsWorld when creating a dynamic body without a PhysicsMass component
Cylinder/sphere GameObjects no longer appear in first frame when draw colliders is enabled on PhysicsDebugDisplay.
Fix bugs in BoundingVolumeHierarchy.Build which now produces BoundingVolumeHierarchy of greater quality. This will affect performance of BVH queries, and most notably it will significantly improve performance of DynamicVsDynamicFindOverlappingPairsJob
Fixed incorrect 3DOF angular constraint solving with non-identity joint orientation
Fixed bug where converted SphereCollider would apply incorrect center offset when in a hierarchy with non-uniform scale.
Fixed bug where converted PhysicsShape would not become part of a compound collider at run-time if the first PhysicsBody ancestor found higher up the hierarchy was disabled.
Fixed bug where leaves of compound shapes in a hierarchy might be added to the wrong entity if it had disabled UnityEngine.Collider components.
Fixed bug causing leaves of compound shapes on prefabs to convert into individual static colliders.
Fixed restitution response to be more bouncy for convex objects with high restitution values
Fixed bug where a converted GameObject in a hierarchy would have the wrong translation and rotation at run-time.
Fixed bug where objects with StaticOptimizeEntity would not be converted into physics world.
Preview for Mesh PhysicsShape no longer culls back faces.
Inspector control for convex radius on PhysisShape now appears when shape type is convex hull.
Known Issues
Attempting to fit a non-uniformly scaled PhysicsShape to its render meshes may produce unexpected results.
Physics objects loaded from sub-scenes may have the wrong transformations applied on Android.
Dragging a control label to modify the orientation of a PhysicsShape sometimes produces small changes in its size.
If gizmos are enabled in the Game tab, the 'Physics Debug Display' viewers are incorrectly rendered. Debug viewers render correctly in the Scene tab.
[0.0.2-preview] - 2019-04-08
Upgrade guide
Any assembly definitions referencing Unity.Physics.Authoring assembly by name must be updated to instead reference Unity.Physics.Hybrid.
Changes
Renamed Unity.Physics.Authoring assembly to Unity.Physics.Hybrid. (All of its types still exist in the Unity.Physics.Authoring namespace.)
Radius of cylinder PhysicsShape is no longer non-uniformly scaled when converted.
Fixes
Fixed exception when converting a box PhysicsShape with negative scale.
Fixed incorrect orientation when fitting capsule, cylinder, or plane PhysicsShape to render mesh.
Fixed convex radius being too large when switching PhysicsShape from plane to box or cylinder.
Fixed calculation of minimum half-angle between faces in convex hulls.
Fixed collision/trigger event iterators skipping some events when iterating.
Fixed memory leak when enabling "Draw colliders" in the Physics Debug Display.
Known Issues
Physics systems are tied to (variable) rendering frame rate when using automatic world bootstrapping. See FixedTimestep examples in ECS Samples project for currently available approaches.
IL2CPP player targets have not yet been fully validated.
Some tests might occasionally fail due to JobTempAlloc memory leak warnings.
Swapping PhysicsShape component between different shape types may produce non-intuitive results when nested in hierarchies with non-uniform scale.
Some PhysicsShape configurations do not bake properly when nested in hierarchies with non-uniform scale.
PhysicsShape does not yet visualize convex hull shapes at edit-time.
Drag values on classic Rigidbody components are not currently converted correctly.