---
title: intersectionFunctionTableOffset
framework: metal
role: symbol
role_heading: Instance Property
path: metal/mtl4accelerationstructuregeometrydescriptor/intersectionfunctiontableoffset
---

# intersectionFunctionTableOffset

Sets the offset that this geometry contributes to determining the intersection function to invoke when a ray intersects it.

## Declaration

```swift
var intersectionFunctionTableOffset: Int { get set }
```

## Discussion

Discussion When you perform a ray tracing operation in the Metal Shading Language, and provide the ray intersector object with an instance of MTLIntersectionFunctionTable, Metal adds this offset to the instance offset from structs such as: MTLAccelerationStructureInstanceDescriptor MTLAccelerationStructureUserIDInstanceDescriptor MTLAccelerationStructureMotionInstanceDescriptor MTLIndirectAccelerationStructureInstanceDescriptor MTLIndirectAccelerationStructureMotionInstanceDescriptor The sum of these offsets provides an index into the intersection function table that the ray tracing system uses to retrieve and invoke the function at this index, allowing you to customize the intersection evaluation process.