AGPHVT-82 : Improve buffer transitions and content copying between frame passes.

include/hvt/engine/framePass.h

@@ -180,9 +180,6 @@ class HVT_API FramePass
 public:
     using Ptr = std::shared_ptr<FramePass>;
 
-    /// A list of frame passes paired with the Hydra tasks used to implement them.
-    using RenderTasks = std::vector<std::pair<FramePass*, PXR_NS::HdTaskSharedPtrVector>>;
-
     /// Constructor
     /// \param name An identifier.
     /// \note An easy identifier can be a short description of the frame pass purpose.
@@ -384,6 +381,19 @@ class HVT_API FramePass
     /// Returns the default selection accessor.
     SelectionSettingsProviderWeakPtr GetSelectionSettingsAccessor() const;
 
+    /// Returns true if the frame pass should be rendered.
+    bool IsEnabled() const { return _enabled; }
+
+    /// Enables or disables the frame pass rendering.
+    void SetEnabled(bool enabled) { _enabled = enabled; }
+
+    // Returns the collection of render buffer bindings to use for the next render pass.
+    /// \param aovs The list of aovs to reuse and continue to fill from the previous pass.
+    /// \param copyContents Controls whether the results from the end of the tasks (non-MSAA) are copied
+    /// to the next pass.  Set to false for simple task lists to avoid copying when unnecessary.
+    hvt::RenderBufferBindings GetRenderBufferBindingsForNextPass(
+        std::vector<pxr::TfToken> const& aovs, bool copyContents = true);
+
 protected:
     /// \brief Build a frame pass unique identifier.
     ///
@@ -404,6 +414,9 @@ class HVT_API FramePass
     static PXR_NS::SdfPath _BuildUID(std::string const& name, std::string const& customPart);
 
 private:
+
+    bool _enabled { true };
+
     /// \brief Short identifier.
     /// \note It should never be changed.
     const std::string _name;

include/hvt/engine/renderBufferSettingsProvider.h

@@ -31,6 +31,7 @@
 
 #include <pxr/imaging/hd/aov.h>
 #include <pxr/imaging/hd/renderBuffer.h>
+#include <pxr/imaging/hgi/texture.h>
 
 #if defined(__clang__)
 #pragma clang diagnostic pop
@@ -47,8 +48,29 @@
 namespace HVT_NS
 {
 
-using RenderBufferBindings =
-    std::vector<std::pair<PXR_NS::TfToken const&, PXR_NS::HdRenderBuffer*>>;
+struct RenderBufferBinding
+{
+    PXR_NS::TfToken aovName;
+    PXR_NS::HgiTextureHandle texture;
+    PXR_NS::HdRenderBuffer* buffer = nullptr;
+    std::string rendererName;
+
+    RenderBufferBinding() = default;
+
+    /// Compares the property values.
+    bool operator==(RenderBufferBinding const& other) const
+    {
+        if (aovName != other.aovName || texture != other.texture || buffer != other.buffer ||
+            rendererName != other.rendererName)
+            return false;
+
+        return true;
+    }
+
+    /// Compares the property values, and negates.
+    bool operator!=(RenderBufferBinding const& other) const { return !(*this == other); }
+};
+using RenderBufferBindings = std::vector<RenderBufferBinding>;
 
 using RenderBufferSettingsProviderWeakPtr = std::weak_ptr<class RenderBufferSettingsProvider>;
 

include/hvt/engine/taskCreationHelpers.h

@@ -175,14 +175,4 @@ HVT_API extern PXR_NS::SdfPath CreateSkyDomeTask(TaskManagerPtr& taskManager,
     RenderBufferSettingsProviderWeakPtr const& renderSettingsProvider,
     FnGetLayerSettings const& getLayerSettings, PXR_NS::SdfPath const& atPos,
     TaskManager::InsertionOrder order);
-
-/// Creates a copy task and inserts it before the atPos.
-/// \param taskManager The task manager to update.
-/// \param atPos The identifier of the task where to insert this new task. If empty, it inserts at
-/// the end of the task's list.
-/// \return The task unique identifier.
-/// \note The task is usually the last one before the present task.
-HVT_API extern PXR_NS::SdfPath CreateCopyTask(
-    TaskManagerPtr& taskManager, PXR_NS::SdfPath const& atPos = PXR_NS::SdfPath());
-
 } // namespace HVT_NS

include/hvt/engine/viewport.h

@@ -48,9 +48,12 @@ class HVT_API Viewport
     /// \param modelInfo The model information.
     /// \param enableFrameCancellation To enable the frame cancellation.
     /// \param usePresentationTask To enable the use of the PresentTask.
-    virtual FramePass::RenderTasks Update(const ViewParams& viewInfo, const ModelParams& modelInfo,
+    virtual void Update(const ViewParams& viewInfo, const ModelParams& modelInfo,
         bool enableFrameCancellation, bool usePresentationTask) = 0;
 
+    // Render the contents of the viewport.
+    virtual void Render() = 0;
+
     /// Creates the render pipeline (using a shared model render pass or not).
     /// \param renderIndex The render index to use where a null one means to create it.
     /// \param is3DCamera To define if the camera is in 3D mode.

source/engine/framePass.cpp

@@ -246,20 +246,32 @@ std::tuple<SdfPathVector, SdfPathVector> FramePass::CreatePresetTasks(PresetTask
 
     if (!IsStormRenderDelegate(GetRenderIndex()) && _bufferManager->IsAovSupported())
     {
-        // Initialize the AOV system to render color, depth and ID buffers.
-        _bufferManager->SetRenderOutputs(
-            { HdAovTokens->color, HdAovTokens->depth, HdAovTokens->primId, HdAovTokens->elementId,
-                HdAovTokens->instanceId },
-            {},
-            _passParams.renderParams.viewport); // NOTE: this is the non-adjusted viewport.
-
         // Set the buffer paths for use with the selection and picking tasks.
         _selectionHelper->SetVisualizeAOV(_bufferManager->GetViewportAov());
     }
 
     return { taskIds, renderTaskIds };
 }
 
+hvt::RenderBufferBindings FramePass::GetRenderBufferBindingsForNextPass(
+    std::vector<pxr::TfToken> const& aovs, bool copyContents)
+{
+    std::string renderName = GetRenderIndex()->GetRenderDelegate()->GetRendererDisplayName();
+
+    hvt::RenderBufferBindings inputAOVs;
+    for (auto& aov : aovs)
+    {
+        pxr::HgiTextureHandle aovTexture;
+        if (copyContents)
+            aovTexture = GetRenderTexture(aov);
+
+        pxr::HdRenderBuffer* aovBuffer   = GetRenderBuffer(aov);
+        inputAOVs.push_back({ aov, aovTexture, aovBuffer, renderName });
+    }
+
+    return inputAOVs;
+}
+
 void FramePass::UpdateScene(UsdTimeCode /*frame*/) {}
 
 HdTaskSharedPtrVector FramePass::GetRenderTasks(RenderBufferBindings const& inputAOVs)