Custom Graph Node

Add a visual-scripting node from a native addon. The node appears in the right-click Add Node menu of any domain you register it with (Material, Shader, Procedural, Animation, FSM, SceneGraph, or your own).

Outcome

A GraphNode subclass with input/output pins and an Evaluate() body.
Auto-registered with one or more GraphDomains via the engine's REGISTER_GRAPH_NODE macro — no engine source changes.
Picked up the moment your addon's DLL loads.

Files to add

Packages/com.example.myaddon/
    Source/
        GraphNodes/
            ClampedAddNode.h
            ClampedAddNode.cpp
        MyAddon.cpp     (existing entry point)

// Source/GraphNodes/ClampedAddNode.h
#pragma once

#include "NodeGraph/GraphNode.h"

class ClampedAddNode : public GraphNode
{
public:
    DECLARE_GRAPH_NODE(ClampedAddNode, GraphNode);

    virtual void SetupPins() override;
    virtual void Evaluate() override;

    virtual const char* GetNodeTypeName() const override { return "Clamped Add"; }
    virtual const char* GetNodeCategory() const override { return "Math";        }
    virtual glm::vec4   GetNodeColor()    const override;
};

Source

// Source/GraphNodes/ClampedAddNode.cpp
#include "GraphNodes/ClampedAddNode.h"
#include "Maths.h"

#include <algorithm>

FORCE_LINK_DEF(ClampedAddNode);
DEFINE_GRAPH_NODE(ClampedAddNode);

// Register with a single domain. Use REGISTER_GRAPH_NODE_MULTI(...) to register
// the same node with several domains at once. Either macro auto-registers at
// static init time when the addon DLL loads — no extra plumbing needed.
//
// Defined in Engine/Source/Engine/NodeGraph/GraphNode.h:
//   REGISTER_GRAPH_NODE(Class, TypeName, Category, DomainName, Color)
//   REGISTER_GRAPH_NODE_MULTI(Class, TypeName, Category, Color, "Domain1", "Domain2", ...)
REGISTER_GRAPH_NODE(
    ClampedAddNode,
    "Clamped Add",
    "Math",
    "SceneGraph",
    glm::vec4(0.4f, 0.6f, 0.2f, 1.0f));

static const glm::vec4 kColor = glm::vec4(0.4f, 0.6f, 0.2f, 1.0f);

void ClampedAddNode::SetupPins()
{
    AddInputPin("A",   DatumType::Float, Datum(0.0f));
    AddInputPin("B",   DatumType::Float, Datum(0.0f));
    AddInputPin("Min", DatumType::Float, Datum(0.0f));
    AddInputPin("Max", DatumType::Float, Datum(1.0f));
    AddOutputPin("Result", DatumType::Float);
}

void ClampedAddNode::Evaluate()
{
    float a    = GetInputValue(0).GetFloat();
    float b    = GetInputValue(1).GetFloat();
    float lo   = GetInputValue(2).GetFloat();
    float hi   = GetInputValue(3).GetFloat();
    float sum  = a + b;
    float clamped = std::min(std::max(sum, lo), hi);
    SetOutputValue(0, Datum(clamped));
}

glm::vec4 ClampedAddNode::GetNodeColor() const { return kColor; }

Wire into the addon

In your existing MyAddon.cpp, force-link the translation unit so the static registrar runs:

#include "GraphNodes/ClampedAddNode.h"

static int OnLoad(PolyphaseEngineAPI* api)
{
    FORCE_LINK_CALL(ClampedAddNode);
    return 0;
}

That's all — the REGISTER_GRAPH_NODE(...) line in the .cpp file does the actual domain registration.

Registering with multiple domains

If your node makes sense in several visual-scripting contexts (e.g. the standard "Input" nodes the engine ships register with every domain), use the _MULTI variant:

REGISTER_GRAPH_NODE_MULTI(
    ClampedAddNode,
    "Clamped Add",
    "Math",
    glm::vec4(0.4f, 0.6f, 0.2f, 1.0f),
    "Material", "Shader", "Procedural", "Animation", "FSM", "SceneGraph");

Domain names are looked up by string. Unknown domain names are silently skipped — typos are not flagged.

Registering with a custom domain

If your addon ships its own GraphDomain subclass (rare), name it in the DomainName argument. The engine creates the domain on first registration if it doesn't exist yet, so the order between domain implementation and node registration is forgiving.

Verification

Reload addons (Tools → Addons → Reload Native Addons).
Open a node graph (e.g. on a Script component or a Material).
Right-click on empty graph space → Math → Clamped Add.
Wire A/B to two values, Min/Max to constants, and check the Result pin updates as you tweak inputs.