wave5-fixed-step-simulation-system-group

Order fixed-step physics systems by scheduling force logic with UpdateBefore(PhysicsSystemGroup) and event processing with UpdateAfter(PhysicsSimulationGroup) inside FixedStepSimulationSystemGroup. This ensures forces apply before the solver and event reads happen after physics simulation.

Collision events are missed when physics systems run in the wrong order relative to PhysicsSystemGroup. You must schedule collision/trigger event reading logic with UpdateAfter(PhysicsSimulationGroup) so it executes after the solver completes.

Use UpdateBefore(PhysicsSystemGroup) for pre-solve logic that writes physics state like PhysicsVelocity, and UpdateAfter(PhysicsSimulationGroup) for post-solve logic that reads solver results such as collision or trigger events during fixed-timestep simulation.

Reading collision events and applying forces in the same system breaks physics ordering. Force writing requires UpdateBefore(PhysicsSystemGroup) while event reading requires UpdateAfter(PhysicsSimulationGroup), so they must be split into separate bursted systems to maintain correct scheduling.

Fixed-step physics logic behaves inconsistently when render-rate assumptions leak into the fixed-step loop. Multiple fixed ticks can occur per frame, so systems must be scheduled inside FixedStepSimulationSystemGroup and avoid render-rate logic to ensure stable simulation timing.

The correct system group for physics-rate logic is FixedStepSimulationSystemGroup. Placing physics-affecting systems here ensures they run at the fixed timestep and can be properly ordered relative to PhysicsSystemGroup and its sub-groups using UpdateBefore and UpdateAfter attributes.