Systems
Cairn
Physics ownership, fixed-step behavior, stable identity, determinism, and the transitional wrapper that exists today.
Cairn is Meridian’s physics family: stable body and shape identity, fixed-step simulation, explicit queries, deterministic modes, structural systems, and dedicated 2D and 3D paths.
Physical behavior in a frame
- 01Commands
Validated changes enter at a controlled simulation boundary.
- 02Fixed steps
Elapsed time is consumed in bounded, repeatable increments.
- 03Physics world
The transitional wrapper advances bodies, collision, and controller state.
- 04Results
Transforms, contacts, and grounded state return through Meridian-owned types.
Current foundation
The public code has a Rapier-backed wrapper behind Meridian types, fixed-step world integration, static collision, kinematic character movement, and a grounded-controller foundation with tests.
This proves an integration boundary and useful behavior. It does not mean Meridian-owned Cairn solver internals exist.
Direction
The adopted direction includes Cairn-native body, shape, query, and solver contracts; provenance-controlled donor work where justified; differential testing; structural destruction as a flagship workload; and a dedicated first-class 2D physics path.
Boundary to remember
Navigation may ask Cairn about traversability and gameplay may react to contacts, but physics does not own game decisions. Stable persistent identity also remains separate from fast process-local handles.