pcg

PCG Skill

PCG (Procedural Content Generation) in UE 5.7 is production-ready and fully scriptable via the PCGPythonInterop plugin. No VibeUE service wrapper is needed — the Python API is complete.

⚠️ Read this before writing any code

These are the mistakes that cause infinite retry loops. Check each one before executing:

Do not call discover_python_class or discover_python_function on any PCG class — this skill contains everything you need. Calling discover bloats context and causes content filter failures.

1. Volume Sampler input pin is "Volume", not "In" — add_edge(input_node, 'In', sampler_node, 'Volume'). Using 'In' silently no-ops and produces 0 points.
2. voxel_size is a Vector, not a float — set_editor_property('voxel_size', unreal.Vector(200, 200, 200)). Passing a float raises a TypeError.
3. graph property on PCGComponent is protected — use pcg_comp.set_graph(graph), never set_editor_property('graph', ...).
4. After modifying a graph, always: save → reload → reassign → generate — skipping reload means the component runs the old cached version.
5. Check for existing nodes before adding — always inspect [type(n.get_settings()).__name__ for n in graph.nodes] first. Adding a node type that already exists creates duplicates that break wiring.
6. Always save AND reload after every change — call save_asset then reload_packages every time. Without the reload the PCG graph editor window won't update and users will think nothing happened.
7. Use Volume Sampler for empty levels, not Surface Sampler — Surface Sampler requires geometry to sample from. An empty level has no geometry, so Surface Sampler always produces 0 points. Use PCGVolumeSamplerSettings with unbounded=True for empty or sparse levels.
8. Never spawn test actors to verify meshes or materials — do not use spawn_actor_from_class to place test cubes. Verify by checking ISM instance counts on the PCGVolume instead: sum(c.get_instance_count() for c in volume.get_components_by_class(unreal.InstancedStaticMeshComponent)).