Glossary

Bake - converting a settled simulating actor into a HISM instance. The actor is destroyed; its final transform becomes a static instance. 

Brush snapshot - the frozen brush settings (radius, spacing, etc.) recorded at the start of a stroke. Lives on the layer for diagnostic purposes; not currently used for replay. 

Cluster - the group of meshes spawned per click or per spacing-tick during a drag. Cluster size determines how many cubes appear simultaneously inside the brush radius. 

HISM (Hierarchical Instanced Static Mesh Component) - UE's standard for rendering many copies of the same mesh efficiently. FT_Chaos creates one HISM per unique source mesh on the manager actor. 

Layer - a named group of HISM instances + simulating actors produced by a single paint stroke. The unit of organization for FT_Chaos work. 

Manager actor - the hidden FT_Chaos_HISM actor in your level that owns all FT_Chaos-spawned HISMs and simulating actors. One per level. Don't delete unless you want to lose all scatter work for that level. 

Multiplier (physics) - global session-scoped value applied to friction or restitution at spawn time. Multiplies against the source mesh's UPhysicalMaterial values. 

Multiplier (scale, per-mesh) - palette-entry-scoped value that combines multiplicatively with the brush's global Min/Max Scale to determine the actual scale range for that mesh's spawns. 

Settled - the state of a simulating actor when its linear and angular velocity have stayed below configured thresholds for LowVelocityTicksToSettle consecutive ticks. Settled actors get baked. 

Simulating actor - a transient AStaticMeshActor with SetSimulatePhysics(true) that exists between spawn and bake. Visible in the outliner under the manager actor as ScatterSimulating_*. 

Stroke - a single click or click-drag from the user. Paint strokes create a layer; erase strokes modify existing layers. 

Transient package - UE's special container for runtime UObjects that should never be saved. Used internally for runtime physical material overrides. 

Undo stack - the linear history of paint and erase strokes, last-in-first-out. The "Undo Last Stroke" button pops from here. 

Weight (palette entry) - relative pick probability when choosing which mesh to spawn. Higher values = more likely to be picked. Zero = never picked.