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# ShaderGraph.NodeDefinition

A description of a node type supported by RealityKit, including its inputs, outputs, and platform availability.

```
struct NodeDefinition
```

## Overview

Obtain definitions from a [`ShaderGraph.NodeLibrary`](/documentation/RealityKit/ShaderGraph/NodeLibrary) and use them to add nodes to a [`ShaderGraph`](/documentation/RealityKit/ShaderGraph).

## Topics

### Structures

[`struct Input`](/documentation/RealityKit/ShaderGraph/NodeDefinition/Input)

[`struct Output`](/documentation/RealityKit/ShaderGraph/NodeDefinition/Output)

[`struct SemanticType`](/documentation/RealityKit/ShaderGraph/NodeDefinition/SemanticType)

### Instance Properties

[`var availability: [ShaderGraph.NodeDefinition.Platform : ShaderGraph.NodeDefinition.Availability]`](/documentation/RealityKit/ShaderGraph/NodeDefinition/availability-swift.property)

The availability of this node definition on each platform.

[`var functionalName: String`](/documentation/RealityKit/ShaderGraph/NodeDefinition/functionalName)

The name of the functional operation this definition implements.

[`var group: String?`](/documentation/RealityKit/ShaderGraph/NodeDefinition/group)

The category this definition belongs to, or `nil` if uncategorized.

[`var inputs: [ShaderGraph.NodeDefinition.Input]`](/documentation/RealityKit/ShaderGraph/NodeDefinition/inputs)

The input ports accepted by this node definition.

[`var name: String`](/documentation/RealityKit/ShaderGraph/NodeDefinition/name)

The unique identifier for this node definition.

[`var outputs: [ShaderGraph.NodeDefinition.Output]`](/documentation/RealityKit/ShaderGraph/NodeDefinition/outputs)

The output ports produced by this node definition.

### Instance Methods

[`func isAvailable(on: ShaderGraph.NodeDefinition.Platform, version: OperatingSystemVersion?) -> Bool`](/documentation/RealityKit/ShaderGraph/NodeDefinition/isAvailable(on:version:))

Returns whether this node definition is available on a given platform and OS version.

### Enumerations

[`enum Availability`](/documentation/RealityKit/ShaderGraph/NodeDefinition/Availability-swift.enum)

[`enum Platform`](/documentation/RealityKit/ShaderGraph/NodeDefinition/Platform)

## Relationships

### Conforms To

[`Equatable`](/documentation/Swift/Equatable)

---

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