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# LowLevelMaterialResource.GeometryModifier

A compiled Metal function that implements the geometry modifier function.

```
final class GeometryModifier
```

## Overview

Create a `GeometryModifier` by calling
[`makeGeometryModifier(descriptor:)`](/documentation/RealityKit/LowLevelRenderContext/makeGeometryModifier(descriptor:)-307ec), or use
[`makeDefaultGeometryModifier()`](/documentation/RealityKit/LowLevelRenderContext/makeDefaultGeometryModifier()) for a pass-through modifier that
performs no vertex transformation.

## Topics

### Creating a geometry modifier

[`struct Descriptor`](/documentation/RealityKit/LowLevelMaterialResource/GeometryModifier/Descriptor)

The name and library for a user-authored Metal geometry modifier function.

### Configuring arguments and parameters

[`var argumentTableDescriptor: LowLevelArgumentTable.Descriptor?`](/documentation/RealityKit/LowLevelMaterialResource/GeometryModifier/argumentTableDescriptor)

The argument table descriptor for this geometry modifier, or `nil` if it takes no
per-draw arguments.

[`var parameterMapping: LowLevelMaterialParameterMapping?`](/documentation/RealityKit/LowLevelMaterialResource/GeometryModifier/parameterMapping)

The parameter name-to-slot mapping for this geometry modifier, or `nil` if it takes no custom parameters.

## Relationships

### Conforms To

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

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

[`Function`](/documentation/RealityKit/LowLevelMaterialResource/Function)

---

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