Subgraphs

A subgraph node represents another graph inside the current graph.

The subgraph node's ports are generated from the inner graph's exposed variables.

A subgraph node in the parent graph. Double-click the node to dive into its inner graph.

Use GraphEditorView when users need to enter subgraphs. The double-click action is handled by the subgraph node element and asks the nearest GraphEditorView to open the inner graph as a new breadcrumb level.

Inside a subgraph. Use exposed variables to define the subgraph node ports, and use the breadcrumb path to return to the parent graph.

Inside the subgraph, ports are not edited directly on the subgraph node. Define variables in the blackboard, then set their flow direction in the inspector:

• Input creates an input port on the parent-facing subgraph node.
• Output creates an output port on the parent-facing subgraph node.
• Input + Output creates both ports.

See Variables and Blackboard for the exact direction mapping.

Local Subgraphs

Local subgraphs are stored inline in the parent graph.

SubgraphNodeModel.Kind.LOCAL points to a graph in the parent model's localSubGraphs list by UID.

Use local subgraphs when the inner graph belongs only to the parent graph.

External Subgraphs

External subgraphs point to an IResourcePath.

SubgraphNodeModel.Kind.EXTERNAL resolves through GraphModel.getReferenceResolver().

Outside an editor context, the resolver can be null. In that case, the subgraph node reuses its cached port shape so existing wires can survive.

Import External Subgraphs from Resources

For resource-backed graph assets, drag a graph resource from the editor resource panel onto the graph canvas.

The editor flow is:

GraphResourceProviderContainer keeps the dragged resource path, so the dropped node stores a stable external reference instead of copying the graph NBT.

The drop is rejected when:

• the graph does not allow subgraph creation,
• the resource is dropped outside the graph content area,
• the resource is the same path as the opened root graph,
• the resource belongs to another graph type and the host graph does not accept it through acceptsSubgraphGraph(...).

After import, the node behaves like any other subgraph node. Double-click it to edit the referenced graph. When editing an external subgraph through a dive-in view, GraphEditorView saves that level back through the reference resolver and SubgraphRegistry refreshes other open graphs that reference the same resource.

Variable Ports

Subgraph node ports are generated from the inner graph's variables:

Inner variable	Outer subgraph node
VariableKind.INPUT	Input port.
VariableKind.OUTPUT	Output port.

READ_WRITE variables create both directions with suffixed port ids.

Use this graph hook to limit exposed variable directions:

@Override
public Set<VariableKind> getSupportedSubgraphVariableKinds() {
    return Set.of(VariableKind.INPUT, VariableKind.OUTPUT);
}

Return an empty set to disable variable-backed subgraph ports.

Cross-Type Subgraphs

Same-type local subgraphs are allowed by default.

For cross-type subgraphs, the host graph must opt in:

@Override
public boolean acceptsSubgraphGraph(Graph other) {
    return other instanceof MaterialGraph;
}

This applies to imported external references and foreign local subgraphs.

External Save Broadcasts

SubgraphRegistry broadcasts when an external graph resource is saved.

Subscribers are:

• root GraphModel instances that need to redefine subgraph node ports,
• editor listeners that may reload or refresh open graph views.

GraphEditorView registers while a graph is loaded and unregisters when cleared.