USDKit Framework

import USDKit
import Foundation

// 1. Open an existing USD stage from a file URL
let sceneURL = Bundle.main.url(forResource: "workbench", withExtension: "usdc")!
let stage = try USDStage.open(sceneURL)

// 2. Traverse the stage hierarchy to check for an existing prim
let existingPrim = stage.prim(at: "/World/Oscilloscope")
if existingPrim == nil {
    print("Oscilloscope not found — adding it now.")
}

// 3. Define a new transform prim at the desired scene path
let transformPrim = stage.definePrim(
    at: "/World/Oscilloscope",
    typeName: "Xform"
)

// 4. Add a lightweight reference to an external asset layer
//    (composition: no data is copied, updates to the source propagate automatically)
let assetURL = Bundle.main.url(forResource: "oscilloscope", withExtension: "usdz")!
transformPrim.addReference(assetURL)

// 5. Move the prim onto the workbench via a translate operation
let translateOp = transformPrim.addTransformOperation(type: .translate)
try translateOp.set(value: SIMD3<Double>(0.0, 0.92, 0.0))

// 6. Apply the USD AccessibilityAPI schema and author metadata
transformPrim.apply(schema: "AccessibilityAPI")
let labelAttr = transformPrim.createAttribute(
    named: "accessibility:label",
    typeName: .string
)
try labelAttr.set(value: "Vintage oscilloscope")

let descAttr = transformPrim.createAttribute(
    named: "accessibility:description",
    typeName: .string
)
try descAttr.set(value: "A vintage analog oscilloscope sitting on the workbench, displaying a sine wave on its green CRT screen.")

// 7. Export a compressed package (mesh ~90% smaller, textures via AVIF)
let outputURL = FileManager.default
    .temporaryDirectory
    .appendingPathComponent("workbench_compressed.usdz")

var options = USDExportOptions()
options.compressMeshes = true
options.compressTextures = true

try stage.exportPackage(to: outputURL, options: options)
print("Exported compressed package to: \(outputURL.path)")