Adding a material to a ModelEntity programmatically

Question

The docs for RealityKit include the structs: OcclusionMaterial, SimpleMaterial, and UnlitMaterial for adding materials to a ModelEntity.

Alternatively you can load in a model with a material attached to it.

I want to add a custom material/texture to a ModelEntity programmatically. How can I achieve this on the fly without adding the material to a model in Reality Composer or some other 3D software?

Answer 1

As you said, there are 3 types of materials in RealityKit at the moment: SimpleMaterial, UnlitMaterial and OcclusionMaterial.

So you can try the following code using SimpleMaterial class:

var material = SimpleMaterial()

material.baseColor = try! .texture(.load(named: "image.jpg"))
material.metallic = MaterialScalarParameter(floatLiteral: 0.9)
material.roughness = MaterialScalarParameter(floatLiteral: 0.1)

/*

material.baseColor = MaterialColorParameter.color(UIColor(red: 0.7,
                                                        green: 0.5,
                                                         blue: 0.2,
                                                        alpha: 1.0))

*/

At the moment there are 4 methods in RealityKit to create simple 3D primitives: generateBox(), generateSphere(), generatePlane() and generateText().

let mesh: MeshResource = .generateBox(size: 2.5)
let component = ModelComponent(mesh: mesh, materials: [material])

print("\(component.mesh.bounds)")
print("\(component.materials.count)")

P.S. At the moment I have no opportunity to test this code in iOS 13 but I hope it's OK.