从 URL 加载图像以获取具有 Swift 的材质纹理

Question

I'm trying to create a custom material from a remote image to add to a ModelEntity with RealityKit. Works totally fine with a local image but trying anything remote I get a loading error.

Fatal error: 'try:' expression unexpectedly raised an error. RealityKit.TextureResource.(unknown context at $1b9817f08).LoadError.importFailureWithURL( https://upload.wikimedia.org/wikipedia/commons/1/1b/Demetrius_III_bust.png )

I've tried multiple images from different source, both http, https, .png, .jpg. Can't find a working example of this anywhere. If it matters the the id I'm passing to withName is a UUID.

func createMaterial(id: String, imageURL: String) -> Material{
        var material = SimpleMaterial()
        material.metallic = MaterialScalarParameter(floatLiteral: 0.0)
        material.roughness = MaterialScalarParameter(floatLiteral: 1.0)
        let texture: TextureResource = try! TextureResource.load(contentsOf: URL(string:imageURL)!, withName: id)

        let materialTexture: MaterialColorParameter = MaterialColorParameter.texture(texture)
        material.baseColor = materialTexture
        return material
 }

PS If anyone can recommend a good library to handle loading and caching images for this sort of use case that would be a huge help. Everything I've found seems targeted towards UIImages or SwiftUI Images.

Update 1: Here is the full error after wrapping the lines in a catch:

[API] URL passed to REAssetManagerTextureNoNetworkSyncMemoryAssetCreateWithURL must be a file URL: https://upload.wikimedia.org/wikipedia/commons/1/1b/Demetrius_III_bust.png

Failed to import entity from " https://upload.wikimedia.org/wikipedia/commons/1/1b/Demetrius_III_bust.png "

I also update my Info.plist's App Transport Security Settings to Allow Arbitrary Loads

Answer 1

Looks like the contentsOf parameter of TextureResource.load() requires an internal file URL not an external URL. I solved this in my case by manually downloading the images I needed first.