Ensure proper metal drawable presentation.

Signed-off-by: furby™ <devs@wabi.foundation>

Sources/UsdView/Hydra/Hydra+RenderEngine.swift

@@ -18,19 +18,32 @@ public enum Hydra
   public class RenderEngine
   {
     public var stage: UsdStageRefPtr
-    public var engine: UsdImagingGL.EngineSharedPtr
+
+    private let hgi: Pixar.HgiMetalPtr
+    private let engine: UsdImagingGL.EngineSharedPtr
 
     public required init(stage: UsdStageRefPtr)
     {
       self.stage = stage
-      engine = UsdImagingGL.Engine.createEngine()
+
+      hgi = HgiMetal.createHgi()
+      let driver = HdDriver(name: .renderDriver, driver: hgi.value)
+
+      engine = UsdImagingGL.Engine.createEngine(
+        rootPath: stage.getPseudoRoot().getPath(),
+        excludedPaths: Sdf.PathVector(),
+        invisedPaths: Sdf.PathVector(),
+        sceneDelegateId: Sdf.Path.absoluteRootPath(),
+        driver: driver
+      )
     }
 
-    public func render()
+    public func render(rgba: (Double, Double, Double, Double))
     {
       var params = UsdImagingGL.RenderParams()
+
       params.frame = Usd.TimeCode.Default()
-      params.clearColor = .init(0.1, 0.1, 0.1, 1.0)
+      params.clearColor = .init(Float(rgba.0), Float(rgba.1), Float(rgba.2), Float(rgba.3))
       params.enableIdRender = false
       params.showGuides = false
       params.showRender = true

Sources/UsdView/Hydra/Hydra+View.swift

@@ -33,12 +33,12 @@ public extension Hydra
 
 public extension Hydra.Viewport
 {
-  init(engine: Hydra.RenderEngine)
+  init(engine: Hydra.RenderEngine, rgba: (Double, Double, Double, Double))
   {
     #if canImport(Metal) && !os(visionOS)
       let device = MTLCreateSystemDefaultDevice()!
       let renderer = Hydra.MTLRenderer(device: device)!
-      self.init(hydra: engine, device: device, renderer: renderer)
+      self.init(hydra: engine, device: device, renderer: renderer, rgba: rgba)
     #endif // canImport(Metal) && !os(visionOS)
   }
 }

Sources/UsdView/Hydra/MTL/Hydra+MTLRenderer.swift

@@ -21,17 +21,17 @@ import PixarUSD
     class MTLRenderer: NSObject, MTKViewDelegate
     {
       private let device: MTLDevice
-      private let commandQueue: MTLCommandQueue
+      //private let commandQueue: MTLCommandQueue
       private var pipelineState: MTLRenderPipelineState?
 
       init?(device: MTLDevice)
       {
         self.device = device
 
-        guard let commandQueue = device.makeCommandQueue()
-        else { return nil }
+        // guard let commandQueue = device.makeCommandQueue()
+        // else { return nil }
 
-        self.commandQueue = commandQueue
+        // self.commandQueue = commandQueue
         super.init()
 
         setupPipeline()
@@ -56,16 +56,21 @@ import PixarUSD
 
       public func draw(in view: MTKView)
       {
-        guard
-          let drawable = view.currentDrawable,
-          let renderPassDescriptor = view.currentRenderPassDescriptor,
-          let pipelineState
-        else { return }
+        guard let drawable = view.currentDrawable else { return }
+        let renderPassDescriptor = view.currentRenderPassDescriptor
+
+        let commandQueue = view.device?.makeCommandQueue()
+        let commandBuffer = commandQueue?.makeCommandBuffer()
 
-        let commandBuffer = commandQueue.makeCommandBuffer()
-        let renderEncoder = commandBuffer?.makeRenderCommandEncoder(descriptor: renderPassDescriptor)
+        var renderEncoder: (any MTLRenderCommandEncoder)? = nil
+        if let renderPassDescriptor {
+          renderEncoder = commandBuffer?.makeRenderCommandEncoder(descriptor: renderPassDescriptor)
+        }
+
+        if let pipelineState { 
+          renderEncoder?.setRenderPipelineState(pipelineState)
+        }
 
-        renderEncoder?.setRenderPipelineState(pipelineState)
         renderEncoder?.setViewport(
           MTLViewport(
             originX: 0.0,

Sources/UsdView/Hydra/MTL/Hydra+MTLView.swift

@@ -38,11 +38,14 @@ import PixarUSD
         private let device: MTLDevice!
         private let renderer: MTLRenderer!
 
-        public init(hydra: Hydra.RenderEngine, device: MTLDevice, renderer: MTLRenderer)
+        var rgba: (Double, Double, Double, Double)
+
+        public init(hydra: Hydra.RenderEngine, device: MTLDevice, renderer: MTLRenderer, rgba: (Double, Double, Double, Double))
         {
           self.hydra = hydra
           self.device = device
           self.renderer = renderer
+          self.rgba = rgba
         }
 
         public func makeCoordinator() -> Coordinator
@@ -55,22 +58,20 @@ import PixarUSD
           let metalView = context.coordinator.metalView
           metalView.device = device
           metalView.delegate = renderer
+          metalView.clearColor = MTLClearColorMake(rgba.0, rgba.1, rgba.2, rgba.3)
           metalView.apply(context.environment)
 
           context.coordinator.setNeedsDisplayTrigger = context.environment.setNeedsDisplayTrigger
 
           return metalView
         }
 
-        public func updateNSView(_: MTKView, context: Context)
+        public func updateNSView(_ view: MTKView, context: Context)
         {
-          context.coordinator.metalView.apply(context.environment)
-          context.coordinator.setNeedsDisplayTrigger = context.environment.setNeedsDisplayTrigger
-
-          renderer.draw(in: context.coordinator.metalView)
-          hydra.render()
+          view.clearColor = MTLClearColorMake(rgba.0, rgba.1, rgba.2, rgba.3)
 
-          print("UPDATE VIEW")
+          renderer.draw(in: view)
+          hydra.render(rgba: rgba)
         }
 
         public class Coordinator

Sources/UsdView/UsdView.swift

@@ -15,6 +15,7 @@ import PixarUSD
 
 #if canImport(SwiftUI)
   import SwiftUI
+
   public protocol PixarApp: App
   {}
 #else
@@ -38,6 +39,10 @@ struct UsdView: PixarApp
   /// the hydra rendering engine.
   let engine: Hydra.RenderEngine
 
+  /// give it a color spectrum...
+  @State var rgba = (0.1, 0.1, 0.1, 1.0)
+  @State var hue = 0.0
+
   public init()
   {
     // register all usd plugins & resources.
@@ -59,8 +64,14 @@ struct UsdView: PixarApp
       {
         VStack
         {
-          Hydra.Viewport(engine: engine)
-            .frame(maxWidth: .infinity, maxHeight: .infinity)
+          Hydra.Viewport(engine: engine, rgba: rgba)
+            .ignoresSafeArea()
+        }
+        .onAppear
+        {
+          #if canImport(SwiftUI)
+            startColorAnimation()
+          #endif // canImport(SwiftUI)
         }
       }
     }

Sources/UsdView/Utils/ShadingUtils.swift

@@ -62,3 +62,34 @@ public func matDef(_ stage: UsdStageRefPtr, color: ShadeColor = ShadeColor.white
 
   return material
 }
+
+#if canImport(SwiftUI)
+  import SwiftUI
+
+  extension UsdView
+  {
+    func startColorAnimation()
+    {
+      Timer.scheduledTimer(withTimeInterval: 0.03, repeats: true)
+      { _ in
+        hue += 0.01
+        if hue > 1.0 { hue = 0.0 }
+        rgba = hueToRGBA(hue: hue)
+      }
+    }
+
+    func hueToRGBA(hue: Double) -> (Double, Double, Double, Double)
+    {
+      let color = Color(hue: hue, saturation: 1.0, brightness: 1.0)
+      var red: Double = 0, green: Double = 0, blue: Double = 0, alpha: Double = 0
+      if let components = color.cgColor?.components, components.count >= 3
+      {
+        red = components[0]
+        green = components[1]
+        blue = components[2]
+        alpha = Double(color.cgColor?.alpha ?? 1.0)
+      }
+      return (red, green, blue, alpha)
+    }
+  }
+#endif // canImport(SwiftUI)