init(named:in:)

Declaration

init(named name: String, in library: any MTLLibrary)

Parameters

• name:

  The name of the geometry modifier function.

• library:

  The Metal library that contains the function.

Discussion

To create a geometry modifier function for a custom material, create a Metal file in your Xcode project. Prefix the function with the keyword [[visible]]. The function needs to take a single parameter of type realitykit::geometry_parameters.

Here’s what a minimal geometry modifier function looks like:

#include <metal_stdlib>
#include <RealityKit/RealityKit.h>
using namespace metal;

[[visible]] void myGeometryModifier(realitykit::geometry_parameters
params) {
    // Use params.geometry().set_model_position_offset() to move the vertex.
}

To create a custom material using this shader, get a reference to your app’s Metal library. You can do that like this:

guard let device = MTLCreateSystemDefaultDevice() else {
    fatalError("Error creating default metal device.")
}
guard let library = maybeDevice.makeDefaultLibrary() else {
    fatalError("Error creating default metal library")
}

Once you’ve got a reference to your Metal library, use it to create the surface shader reference like this:

let geometryModifier = CustomMaterial.GeometryModifier(
    named: "myGeometryModifier",
    in: library
)

For more information on creating custom materials and writing shader functions, see Modifying RealityKit rendering using custom materials.