Use cases

Vegetation scatter

• Landscape/surface -> slope/height/surface attributes -> road/water/POI Difference -> density noise -> weighted species selection -> bounded transform -> instanced mesh spawn.
• Partition/hierarchy by plant scale: trees on larger grids, grass/flowers/stones on smaller.
• Keep gameplay clearance, landmarks, paths, and sightlines as hard filters.
• Use persistent CPU instances when HLOD/collision/nav are required; GPU instances only for the supported purely visual runtime case.

Roadside/fence generator

• Spline input -> distance sampling -> tangent/side/width -> terrain projection -> intersection/ endpoint rules -> post/module selection -> spawn.
• Use Shape Grammar for repeating modules and corner/end pieces when rules stay legible.
• Route spline deformation/mesh segment details to $unreal-splines.

Building/city blocks

• Polygon 2D city boundary -> cut/subdivide by splines -> offset for setbacks -> create surfaces -> sample parcels -> attribute-driven building archetype -> Spawn Actor/Level Instance.
• Keep roads and utility corridors as source geometry, not late random exclusions.
• Validate entrances, navigation, collision, streaming ownership, and HLOD output.

Biome architecture

• Separate climate/biome classification, broad distribution, species selection, local exclusion, and spawn into subgraphs.
• Use Data Assets/Tables for species rules and weights.
• PCG Biome Core is Experimental; mine it for patterns rather than treating it as a production guarantee.

Authored exceptions

• Use input splines/volumes/tags for repeatable design rules.
• Use UE 5.8 manual overrides for isolated art-directed exceptions only after accepting the Experimental status and defining merge/regeneration policy.
• If the same override occurs repeatedly, promote it into graph input or rule data.

Acceptance test for any generator

The generator must produce valid constraints across at least ten representative seeds, regenerate identically for a fixed seed/input, survive cleanup/reload/cook, remain editable by intended creators, and meet total runtime/render/streaming budgets on target hardware.