Fix imaging crash potential, begin UsdView hydra.

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

Sources/PixarUSD/UsdImaging/UsdImagingGLEngine/UsdImagingGLEngine.swift

@@ -0,0 +1,18 @@
+/* ----------------------------------------------------------------
+ * :: :  M  E  T  A  V  E  R  S  E  :                            ::
+ * ----------------------------------------------------------------
+ * Licensed under the terms set forth in the LICENSE.txt file, this
+ * file is available at https://openusd.org/license.
+ *
+ *                                        Copyright (C) 2016 Pixar.
+ *         Copyright (C) 2024 Wabi Foundation. All Rights Reserved.
+ * ----------------------------------------------------------------
+ *  . x x x . o o o . x x x . : : : .    o  x  o    . : : : .
+ * ---------------------------------------------------------------- */
+
+#if canImport(UsdImagingGLEngine)
+  import UsdImagingGLEngine
+
+  public enum UsdImagingGLEngine
+  {}
+#endif // canImport(UsdImagingGLEngine)

Sources/UsdImaging/indexProxy.cpp

@@ -251,11 +251,10 @@ void UsdImagingIndexProxy::InsertInstancer(SdfPath const &cachePath,
     primInfo->dirtyBits = HdChangeTracker::AllDirty;
     _delegate->_dirtyCachePaths.insert(cachePath);
 
-    auto& adapterType = (*adapter);
     TF_DEBUG(USDIMAGING_INSTANCER)
         .Msg("[Instancer Inserted] %s, adapter = %s\n",
              cachePath.GetText(),
-             adapter ? TfType::GetCanonicalTypeName(typeid(adapterType)).c_str() : "none");
+             adapter ? TfType::GetCanonicalTypeName(typeid(*adapter)).c_str() : "none");
 
     _AddTask(cachePath);
   }

Sources/UsdImaging/instanceAdapter.cpp

@@ -335,13 +335,12 @@ SdfPath UsdImagingInstanceAdapter::_Populate(UsdPrim const &prim,
         protoPath = newProtoPath;
       }
 
-      auto& primAdapterType = (*primAdapter);
       TF_DEBUG(USDIMAGING_INSTANCER)
           .Msg("[Add Instance NI] <%s>  %s (%s), adapter = %s\n",
                instancerPath.GetText(),
                protoPath.GetText(),
                iter->GetName().GetText(),
-               primAdapter ? TfType::GetCanonicalTypeName(typeid(primAdapterType)).c_str() : "none");
+               primAdapter ? TfType::GetCanonicalTypeName(typeid(*primAdapter)).c_str() : "none");
     }
   }
 

Sources/UsdImagingGL/include/UsdImagingGL/engine.h

@@ -65,6 +65,7 @@ TF_DECLARE_REF_PTRS(HdsiSceneGlobalsSceneIndex);
 TF_DECLARE_REF_PTRS(HdSceneIndexBase);
 
 using UsdStageWeakPtr = TfWeakPtr<class UsdStage>;
+using UsdImagingGLEngineSharedPtr = std::shared_ptr<class UsdImagingGLEngine>;
 
 namespace UsdImagingGLEngine_Impl {
 using _AppSceneIndicesSharedPtr = std::shared_ptr<struct _AppSceneIndices>;

Sources/UsdView/Hydra+MTLRenderer.swift

@@ -0,0 +1,71 @@
+/* ----------------------------------------------------------------
+ * :: :  M  E  T  A  V  E  R  S  E  :                            ::
+ * ----------------------------------------------------------------
+ * Licensed under the terms set forth in the LICENSE.txt file, this
+ * file is available at https://openusd.org/license.
+ *
+ *                                        Copyright (C) 2016 Pixar.
+ *         Copyright (C) 2024 Wabi Foundation. All Rights Reserved.
+ * ----------------------------------------------------------------
+ *  . x x x . o o o . x x x . : : : .    o  x  o    . : : : .
+ * ---------------------------------------------------------------- */
+
+import Foundation
+import PixarUSD
+#if canImport(Metal) && !os(visionOS)
+  import Metal
+  import MetalKit
+
+  public extension Hydra
+  {
+    /**
+     * ``MTLRenderer``
+     *
+     * ## Overview
+     *
+     * The Hydra Engine (``Hd``) Metal renderer for the ``UsdView``
+     * application conforms to the ``MTKViewDelegate`` protocol,
+     * allowing it to be set as a ``MTKView`` object's delegate to
+     * provide a drawing method to a ``MTKView`` object and respond
+     * to rendering events. */
+    class MTLRenderer: NSObject, MTKViewDelegate
+    {
+      let hgi: Pixar.HgiMetalPtr
+      // let engine: UsdImagingGLEngineSharedPtr
+      // let stage: UsdStageRefPtr
+
+      public init?(device _: MTLDevice)
+      {
+        hgi = HgiMetal.createHgi()
+
+        // let excludedPaths = SdfPathVector()
+        let driver = HdDriver(name: .renderDriver, driver: VtValue(hgi))
+
+        // engine.reset(UsdImagingGLEngineSharedPtr(
+        //   stage.getPseudoRoot().getPath(),
+        //   excludedPaths,
+        //   SdfPathVector(),
+        //   SdfPath.AbsoluteRootPath(),
+        //   driver
+        // ))
+
+        // engine.SetEnablePresentation(false)
+        // engine.SetRendererAov(false)
+      }
+
+      public func info()
+      {
+        Msg.logger.log(level: .info, "Created HGI -> Metal API v\(hgi.apiVersion).")
+        Msg.logger.log(level: .info, "GPU Architecture -> \(hgi.device.architecture.name)")
+      }
+
+      public func mtkView(_: MTKView, drawableSizeWillChange size: CGSize)
+      {
+        print("drawableSizeWillChange", size)
+      }
+
+      public func draw(in _: MTKView)
+      {}
+    }
+  }
+#endif // canImport(Metal) && !os(visionOS)

Sources/UsdView/Hydra.swift

@@ -0,0 +1,17 @@
+/* ----------------------------------------------------------------
+ * :: :  M  E  T  A  V  E  R  S  E  :                            ::
+ * ----------------------------------------------------------------
+ * Licensed under the terms set forth in the LICENSE.txt file, this
+ * file is available at https://openusd.org/license.
+ *
+ *                                        Copyright (C) 2016 Pixar.
+ *         Copyright (C) 2024 Wabi Foundation. All Rights Reserved.
+ * ----------------------------------------------------------------
+ *  . x x x . o o o . x x x . : : : .    o  x  o    . : : : .
+ * ---------------------------------------------------------------- */
+
+import Foundation
+import PixarUSD
+
+public enum Hydra
+{}

Sources/UsdView/UsdView.swift

@@ -40,7 +40,7 @@ import PixarUSD
 struct UsdView: PixarApp
 {
   #if canImport(Metal) && !os(visionOS)
-    let hydra: HDMTLRenderer
+    let hydra: Hydra.MTLRenderer
   #endif /* canImport(Metal) && !os(visionOS) */
 
   public init()
@@ -65,7 +65,7 @@ struct UsdView: PixarApp
     #endif /* canImport(PyBundle) */
 
     #if canImport(Metal) && !os(visionOS)
-      hydra = HDMTLRenderer(device: MTLCreateSystemDefaultDevice()!)!
+      hydra = Hydra.MTLRenderer(device: MTLCreateSystemDefaultDevice()!)!
     #endif /* canImport(Metal) && !os(visionOS) */
 
     #if canImport(SwiftUI)