Découvrez USDKit et les nouveautés d’OpenUSD

8:12 - Opening a USD Stage

import USDKit

// Create a new empty in-memory stage

let stage = USDStage()

// Open a stage from a file on disk

let url = URL(fileURLWithPath: "/ALab/entry.usda")
let stage = try USDStage.open(url)

8:44 - Traversing the Stage Hierarchy

// Traverse all prims looking for the oscilloscope
for prim in stage.descendants {
    if prim.name == "scope" {
        // There it is! 🔬
    }
}

// It wasn't there — define a new Xform prim for it

let scope = stage.definePrim(at: "/World/scope", type: “Xform"))
                             
// Add a file reference to the prim

try scope.references.add(“/ALab/assets/scope.usda”)

9:36 - Moving a Prim with a Transform Operation

// Creates xformOp:translate and updates xformOpOrder automatically

scope.addTransformOperation(type: .translate)
scope["xformOp:translate", as: USDValue.Vec3d.self] = [2.5, 0.0, -1.0]

10:42 - Applying Accessibility Metadata

// Apply the multi-apply AccessibilityAPI schema with instance name "default"

try scope.applyAPISchema("AccessibilityAPI", instanceName:"default")

// Create the label and description attributes

scope.makeAttribute(named: "accessibility:default:label", as: .string)
scope.makeAttribute(named: "accessibility:default:description", as: .string)

// Set their values

scope["accessibility:default:label", as: String.self] = "Oscilloscope"
scope["accessibility:default:description", as: String.self] = 
    "Vintage signal analyzer with a 3D wireframe display, topped by a color bar test monitor"

12:05 - Exporting with Mesh and Texture Compression

let output = URL(fileURLWithPath: "/ALab/alab_compressed.usdz")

// Export the stage as a USDZ package

try stage.exportPackage(
    to: output,
    options: [
        .preferSmallTextureFiles(quality: .standard),   // compress textures
        .preferSmallMeshFiles                           // compress mesh geometry
    ]
)