Procedural

20 tools. Back to the index.

add_pcg_component

Additive, idempotent.

Attach a PCG component (the procedural generation engine) to an actor and optionally point it at a PCG graph -- what turns a plain actor or volume into something that scatters meshes and points by rule. Idempotent: an actor that already has one gets it back. The component generates within the actor's BOUNDS, so on a volume with no brush geometry it produces zero instances with no error at all -- confirm the extent with get_actor_bounds first. Then run generate_pcg_component and inspect with get_pcg_component_info.

Parameter	Type	Required	Description
actor_name	string	yes	Display label or internal name of the target editor-world actor (required)
pcg_graph_path	string	no	Optional /Game/... path of a UPCGGraph to assign to the component

Returns: { actor_name, component_name, already_existed, graph_path, graph_assigned }

add_pcg_graph_parameter

Additive, idempotent.

Expose a tunable on a PCG graph (bool / int / float / double / string) so density, radius or a toggle can be driven from outside instead of being welded into a node. Idempotent (already_existed when the name is taken). Only worth doing on graphs you own -- adding one to a library graph means editing that asset. Set a value with set_pcg_graph_parameter and list them with get_pcg_graph_parameters.

Parameter	Type	Required	Description
pcg_graph_path	string	yes	/Game/... path to the UPCGGraph (required)
name	string	yes	Parameter name (required)
type	string	yes	"bool" | "int" | "float" | "double" | "string" (required)

Returns: { pcg_graph_path, name, type, added, already_existed, parameter_count }

add_pcg_node

Additive.

Adds a node of the given UPCGSettings subclass to a PCG graph. Uses UPCGGraph::AddNodeOfType, which creates the node's settings in the transient package and reparents the node into the graph (headless-safe). The graph is re-saved after the mutation.

Parameter	Type	Required	Description
pcg_graph_path	string	yes	Asset path of the PCG Graph (e.g. "/Game/PCG/PCG_Example" or fully-qualified "/Game/PCG/PCG_Example.PCG_Example").
node_type	string	yes	A concrete UPCGSettings subclass name, e.g. "PCGSurfaceSamplerSettings", "PCGStaticMeshSpawnerSettings", or a fully-qualified "/Script/PCG.PCGSurfaceSamplerSettings".

Returns: { graph_name: string, asset_path: string, node_title: string, node_name: string, settings_class: string, node_count: int, saved: bool, save_error: string }

add_pcg_subgraph_node

Additive.

Embed one PCG graph inside another as a Subgraph node -- how you reuse a scatter or filter recipe across biomes instead of duplicating nodes, and how you consume a library graph without editing it. Check first with get_pcg_graph_info that the target graph actually USES its input node (a graph with no edges from its default input cannot be fed filtered data and will ignore whatever you wire in), and with get_pcg_graph_parameters whether it exposes anything tunable.

Parameter	Type	Required	Description
pcg_graph_path	string	yes	/Game/... path to the host UPCGGraph (required)
subgraph_path	string	yes	/Game/... path to the UPCGGraph to embed as a subgraph (required)

Returns: { graph_name, asset_path, node_name, node_title, subgraph_path, subgraph_set, node_count, saved }

cleanup_pcg_component

Destructive.

Wipe a PCG component's generated output synchronously -- and the step you must not skip after editing a graph: a plain generate_pcg_component with force reuses the CACHED result, so the world keeps the STALE meshes and settings while every flag reads generated:true. Call this with remove_components=true FIRST, then generate, then verify by re-reading the actor's spawned components rather than the generated flag. Also the way to clear procedural content before moving or resizing the volume.

Parameter	Type	Required	Description
actor_name	string	yes	Actor holding the UPCGComponent (required)
remove_components	boolean	no	Optional; also remove spawned managed components (default false)

Returns: { actor_name, cleaned, generated }

connect_pcg_nodes

Destructive, idempotent.

Connects two PCG nodes by adding a directed edge from an output pin to an input pin. Node names come from get_pcg_graph_info; the implicit graph endpoints are addressable as "Input"/"Output". from_pin/to_pin default to the node's "Out"/"In" pin (else its first pin); the resolved labels are echoed in the response. Idempotent: an existing edge reports already_connected without error. The graph is re-saved after a new edge is added.

Parameter	Type	Required	Description
pcg_graph_path	string	yes	Asset path of the PCG Graph (e.g. "/Game/PCG/PCG_Example" or fully-qualified "/Game/PCG/PCG_Example.PCG_Example").
from_node	string	yes	Upstream node: a node_name from get_pcg_graph_info, or the token "Input" for the graph's implicit input node.
to_node	string	yes	Downstream node: a node_name, or the token "Output" for the graph's implicit output node.
from_pin	string	no	Optional output-pin label on from_node (default the node's "Out" pin, else its first output pin).
to_pin	string	no	Optional input-pin label on to_node (default the node's "In" pin, else its first input pin).

Returns: { graph_name: string, asset_path: string, from_node: string, from_pin: string, to_node: string, to_pin: string, already_connected: bool, connected: bool, edge_count: int, saved: bool, save_error: string }

create_pcg_graph

Additive.

Creates (or loads, idempotently) a UPCGGraph asset and saves it. Uses CreatePackage + NewObject<UPCGGraph> (headless-safe). A fresh PCG graph has the implicit Input/Output nodes; node_count counts user-added nodes only (initially 0). Requires the PCG plugin to be enabled.

Parameter	Type	Required	Description
name	string	yes	Name of the PCG Graph asset to create.
package_path	string	no	Destination /Game folder (default /Game/PCG).

Returns: { graph_name: string, asset_path: string, created: bool, already_exists: bool, node_count: int, saved: bool, save_error: string }

disconnect_pcg_nodes

Destructive, idempotent.

Removes the directed edge between two PCG nodes' pins. Pin labels default to the node's "Out"/"In" pin (else its first pin) and the resolved labels are echoed. Idempotent: if no such edge exists it reports already_disconnected without error. The graph is re-saved after an edge is removed.

Parameter	Type	Required	Description
pcg_graph_path	string	yes	Asset path of the PCG Graph (e.g. "/Game/PCG/PCG_Example").
from_node	string	yes	Upstream node name, or the token "Input".
to_node	string	yes	Downstream node name, or the token "Output".
from_pin	string	no	Optional output-pin label on from_node (default the node's "Out" pin, else its first output pin).
to_pin	string	no	Optional input-pin label on to_node (default the node's "In" pin, else its first input pin).

Returns: { graph_name: string, asset_path: string, from_node: string, from_pin: string, to_node: string, to_pin: string, already_disconnected: bool, removed: bool, disconnected: bool, edge_count: int, saved: bool, save_error: string }

generate_pcg_component

Additive.

Triggers PCG generation on an actor's UPCGComponent. Generation is ASYNCHRONOUS (scheduled on the PCG subsystem, resolved over subsequent editor ticks) — this returns the scheduled task id, NOT a finished result. Poll get_pcg_component_info / get_pcg_generated_data for completion (honest).

Parameter	Type	Required	Description
actor_name	string	yes	Actor holding the UPCGComponent (required)
force	boolean	no	Optional; force regeneration even if already generated (default true)

Returns: { actor_name, scheduled, task_id, is_generating, generated, note }

get_pcg_component_info

Read-only.

Read an actor's PCG component: which graph it runs, its seed, whether it is generating or already generated, activated, partitioned, and its generation trigger. Read-only. Use it to find which graph is driving an actor and to confirm a seed for deterministic scatter -- but NOT as proof the world matches the graph: generated:true is satisfied by a cached result, so after editing a graph the flag says done while the spawned meshes are stale. The real check is the actor's spawned components (get_pcg_generated_data / get_components_by_class), after cleanup_pcg_component + generate_pcg_component.

Parameter	Type	Required	Description
actor_name	string	yes	Actor holding the UPCGComponent (required)

Returns: { actor_name, has_component, graph_path, is_generating, generated, seed, activated, is_partitioned, generation_trigger }

get_pcg_generated_data

Read-only.

Reports the generated output of an actor's UPCGComponent: per output item, its pin, tags and data class. Read-only; empty until a generation completes (generation is asynchronous).

Parameter	Type	Required	Description
actor_name	string	yes	Actor holding the UPCGComponent (required)

Returns: { actor_name, has_component, output_data_count, data:[{index, pin, data_class, tags:[...]}], note? }

get_pcg_graph_info

Read-only.

Reads the structure of a UPCGGraph: node count, per-node titles and pin labels, and every directed edge. Pin labels and the input_node_name/output_node_name feed connect_pcg_nodes / disconnect_pcg_nodes; the implicit graph endpoints are also addressable by the tokens "Input"/"Output".

Parameter	Type	Required	Description
pcg_graph_path	string	yes	Asset path of the PCG Graph (e.g. "/Game/PCG/PCG_Example" or fully-qualified "/Game/PCG/PCG_Example.PCG_Example").

Returns: { graph_name: string, asset_path: string, node_count: int, nodes: [{node_name, title, settings_class, input_pins: [string], output_pins: [string]}], has_input_node: bool, has_output_node: bool, input_node_name: string, output_node_name: string, edges: [{from_node, from_pin, to_node, to_pin}], edge_count: int }

get_pcg_graph_parameters

Read-only.

List a PCG graph's user parameters with name, type and current value -- and the read that decides whether a THIRD-PARTY graph can be reused without editing it. An empty list means nothing is exposed: meshes, densities and exclusions are welded inside, so the only way to change them is to edit the asset, which is not an option for a read-only library graph. Read-only. Note it accepts a PCGGraph asset, not a PCGGraphInstance -- overriding a parameter on an instance has no headless route and must be ticked in the details panel.

Parameter	Type	Required	Description
pcg_graph_path	string	yes	/Game/... path to the UPCGGraph (required)

Returns: { pcg_graph_path, parameter_count, parameters:[{name, type, value}] }

get_pcg_node_properties

Read-only.

Reads every editable property of a PCG node's settings object via reflection. The node is resolved by name from get_pcg_graph_info (or the "Input"/"Output" tokens); its UPCGSettings is serialized to JSON. Read-only.

Parameter	Type	Required	Description
pcg_graph_path	string	yes	Asset path of the PCG Graph (e.g. "/Game/PCG/PCG_Example" or fully-qualified "/Game/PCG/PCG_Example.PCG_Example").
node_name	string	yes	The node_name from get_pcg_graph_info of the node to read (the tokens "Input"/"Output" address the implicit endpoints).

Returns: { graph_name: string, asset_path: string, node_name: string, settings_class: string, properties: object }

list_pcg_node_types

Read-only.

Enumerate every PCG node type available in this build (all concrete PCGSettings subclasses, including plugin- and project-added ones), with class names and paths. Run it before add_pcg_node so you pass a class that exists instead of guessing a name from documentation that may not match this engine version. Read-only reflection.

No parameters.

Returns: { base_class, count, types:[{name, path}] }

remove_pcg_node

Destructive, idempotent.

Removes a user-added node from a PCG graph by name. Uses UPCGGraph::RemoveNode, which auto-breaks the node's edges and notifies its neighbours; the graph is re-saved after the mutation. The implicit Input/Output endpoint nodes cannot be removed (doing so would silently corrupt the graph) and are rejected with an honest error. Idempotent: a node that is not present reports already_removed without error.

Parameter	Type	Required	Description
pcg_graph_path	string	yes	Asset path of the PCG Graph (e.g. "/Game/PCG/PCG_Example" or fully-qualified "/Game/PCG/PCG_Example.PCG_Example").
node_name	string	yes	The node_name from get_pcg_graph_info of the node to remove. The tokens "Input"/"Output" (and the endpoints' real names) are rejected: the implicit graph endpoints cannot be removed.

Returns: { graph_name: string, asset_path: string, node_name: string, removed: bool, already_removed: bool, node_count: int, saved: bool, save_error: string }

set_pcg_component_properties

Destructive, idempotent.

Sets properties on an actor's UPCGComponent by reflection (Seed, bActivated, bIsComponentPartitioned, GenerationTrigger, ...). Reads the stored values back into the response.

Parameter	Type	Required	Description
actor_name	string	yes	Actor holding the UPCGComponent (required)
properties	object	yes	JSON object { PropertyName: value, ... } applied to the component

Returns: { actor_name, set:[name], failed:[{name, error}], applied:{name: stored_value_text} }

set_pcg_graph_parameter

Destructive, idempotent.

Write the value of an existing PCG graph user parameter (bool / int / float / double) and read the stored value back, so the reply is its own oracle -- how you tune scatter density or a rule threshold without opening the graph. The parameter must already exist (add_pcg_graph_parameter) and the value type must match. IMPORTANT: it accepts a PCGGraph ASSET only and answers "PCG graph not found" for a PCGGraphInstance -- per-instance overrides have no headless route and must be ticked in the details panel. Changing a parameter does not update the world: cleanup_pcg_component then generate_pcg_component, or the cached output is reused.

Parameter	Type	Required	Description
pcg_graph_path	string	yes	/Game/... path to the UPCGGraph (required)
name	string	yes	Parameter name (must already exist; add with add_pcg_graph_parameter) (required)
value	string	no	New value; its type must match the parameter's declared type (required)

Returns: { pcg_graph_path, name, type, set, value }

set_pcg_node_properties

Destructive, idempotent.

Authors a PCG node's settings object via reflection (partial merge + clamp). Only the keys present in properties are written; absent keys are untouched. After the merge, PostEditChange() invalidates the node's cached CRC and regenerates its pins. The graph is re-saved and the persisted settings are read back. Idempotent: re-applying the same values is a no-op.

Parameter	Type	Required	Description
pcg_graph_path	string	yes	Asset path of the PCG Graph (e.g. "/Game/PCG/PCG_Example" or fully-qualified "/Game/PCG/PCG_Example.PCG_Example").
node_name	string	yes	The node_name from get_pcg_graph_info of the node to author (the tokens "Input"/"Output" address the implicit endpoints).
properties	object	yes	Object of UPCGSettings fields to merge (e.g. for a SurfaceSampler: bApplyDensityToPoints(bool), PointsPerSquaredMeter(float>=0), Looseness(float)); absent keys untouched.

Returns: { graph_name: string, asset_path: string, node_name: string, settings_class: string, applied_keys: [string], properties: object, saved: bool, save_error: string }

spawn_pcg_volume

Additive.

Spawns an APCGVolume in the editor world with a REAL cube brush (from extent), optionally assigning a graph. Bounds, origin, scale and brush geometry are RE-READ from the spawned actor, never echoed. Without extent the volume is spawned brush-less (kept for compatibility) and the response says so explicitly, because a PCG component with null bounds generates 0 instances in total silence.

Parameter	Type	Required	Description
location	array	no	World location [X, Y, Z] for the volume.
extent	array	no	Cube HALF-size [x, y, z] in unreal units, each > 0 (same convention as spawn_box_volume / spawn_navmesh_bounds_volume). STRONGLY RECOMMENDED: omitting it leaves the volume with extent (0,0,0) and the PCG component generates 0 instances with no error and no warning.
rotation	array	no	Optional [pitch, yaw, roll] rotation for the volume (default 0,0,0).
pcg_graph_path	string	no	Optional content path of a UPCGGraph to assign to the spawned volume's PCG component.
name	string	no	Optional explicit name (skipped if already used in the current level to avoid Rename-onto-occupied crash).

Returns: { actor_name: string, actor_label: string, actor_class: string, has_pcg_component: bool, pcg_graph_path: string, graph_assigned: bool, location: [float], bounds_extent_actual: [float], bounds_origin_actual: [float], actor_scale: [float], has_brush_geometry: bool, brush_poly_count: int, brush_requested: bool, scale_normalized: bool, warning?: string, requested: {...} }