ClearsBuffers: make the RenderViews store clearbuffers values

This then allows to only do value lookup at submission time rather than
accessing the backend node. This will be a great help when submission and
frame processing are later on parallelized.

Change-Id: I0d34251d67f8329f486626642d7d2eccef9ddf18
Task-number: QTBUG-54423
Reviewed-by: Paul Lemire <paul.lemire@kdab.com>

4 files changed, 46 insertions, 17 deletions

diff --git a/src/render/backend/renderer.cpp b/src/render/backend/renderer.cpp
index b062c93f2..64fa4ffc4 100644
--- a/src/render/backend/renderer.cpp
+++ b/src/render/backend/renderer.cpp
@@ -708,8 +708,10 @@ Renderer::ViewSubmissionResultData Renderer::submitRenderViews(const QVector<Ren
 
         // set color, depth, stencil clear values (only if needed)
         auto clearBufferTypes = renderView->clearTypes();
-        if (clearBufferTypes & QClearBuffers::ColorBuffer && renderView->globalClearColorBuffers() != nullptr)
-            m_graphicsContext->clearColor(renderView->globalClearColorBuffers()->clearColorAsColor());
+        if (clearBufferTypes & QClearBuffers::ColorBuffer) {
+            const QVector4D vCol = renderView->globalClearColorBufferInfo().clearColor;
+            m_graphicsContext->clearColor(QColor::fromRgbF(vCol.x(), vCol.y(), vCol.z(), vCol.w()));
+        }
         if (clearBufferTypes & QClearBuffers::DepthBuffer)
             m_graphicsContext->clearDepthValue(renderView->clearDepthValue());
         if (clearBufferTypes & QClearBuffers::StencilBuffer)
@@ -720,14 +722,9 @@ Renderer::ViewSubmissionResultData Renderer::submitRenderViews(const QVector<Ren
 
         // if there are ClearColors set for different draw buffers,
         // clear each of these draw buffers individually now
-        const QVector<const ClearBuffers*> clearDrawBuffers = renderView->specificClearColorBuffers();
-        for (const ClearBuffers *clearBuffer : clearDrawBuffers) {
-            if (!clearBuffer->bufferId().isNull()) {
-                const RenderTargetOutput *buffer = m_nodesManager->attachmentManager()->lookupResource(clearBuffer->bufferId());
-                const int drawBufferIndex = renderView->attachmentPack().getDrawBufferIndex(buffer->point());
-                m_graphicsContext->clearBufferf(drawBufferIndex, clearBuffer->clearColor());
-            }
-        }
+        const QVector<ClearBufferInfo> clearDrawBuffers = renderView->specificClearColorBufferInfo();
+        for (const ClearBufferInfo &clearBuffer : clearDrawBuffers)
+            m_graphicsContext->clearBufferf(clearBuffer.drawBufferIndex, clearBuffer.clearColor);
 
         // Set the Viewport
         m_graphicsContext->setViewport(renderView->viewport(), renderView->surfaceSize() * renderView->devicePixelRatio());
diff --git a/src/render/backend/renderview.cpp b/src/render/backend/renderview.cpp
index b8c7f772a..0f74239b6 100644
--- a/src/render/backend/renderview.cpp
+++ b/src/render/backend/renderview.cpp
@@ -243,7 +243,6 @@ RenderView::RenderView()
     , m_viewport(QRectF(0.0f, 0.0f, 1.0f, 1.0f))
     , m_surface(nullptr)
     , m_clearBuffer(QClearBuffers::None)
-    , m_globalClearColorBuffer(nullptr)
     , m_stateSet(nullptr)
     , m_noDraw(false)
     , m_compute(false)
@@ -361,11 +360,22 @@ void RenderView::addClearBuffers(const ClearBuffers *cb) {
     // keep track of global ClearColor (if set) and collect all DrawBuffer-specific
     // ClearColors
     if (type & QClearBuffers::ColorBuffer) {
+        ClearBufferInfo clearBufferInfo;
+        clearBufferInfo.clearColor = cb->clearColor();
+
         if (cb->clearsAllColorBuffers()) {
-            m_globalClearColorBuffer = cb;
+            m_globalClearColorBuffer = clearBufferInfo;
             m_clearBuffer |= QClearBuffers::ColorBuffer;
         } else {
-            m_specificClearColorBuffers.push_back(cb);
+            if (cb->bufferId()) {
+                const RenderTargetOutput *targetOutput = m_manager->attachmentManager()->lookupResource(cb->bufferId());
+                if (targetOutput) {
+                    clearBufferInfo.attchmentPoint = targetOutput->point();
+                    // Note: a job is later performed to find the drawIndex from the buffer attachment point
+                    // using the AttachmentPack
+                    m_specificClearColorBuffers.push_back(clearBufferInfo);
+                }
+            }
         }
     }
 }
diff --git a/src/render/backend/renderview_p.h b/src/render/backend/renderview_p.h
index 0596b28b1..0b01744e9 100644
--- a/src/render/backend/renderview_p.h
+++ b/src/render/backend/renderview_p.h
@@ -105,6 +105,13 @@ struct Q_AUTOTEST_EXPORT Plane
     const float d;
 };
 
+struct Q_AUTOTEST_EXPORT ClearBufferInfo
+{
+    int drawBufferIndex = 0;
+    QRenderTargetOutput::AttachmentPoint attchmentPoint = QRenderTargetOutput::Color0;
+    QVector4D clearColor;
+};
+
 // This class is kind of analogous to RenderBin but I want to avoid trampling
 // on that until we get this working
 
@@ -177,8 +184,10 @@ public:
     // color ClearBuffers are collected, as there may be multiple
     // color buffers to be cleared. we need to apply all these at rendering
     void addClearBuffers(const ClearBuffers *cb);
-    inline QVector<const ClearBuffers*> specificClearColorBuffers() const { return m_specificClearColorBuffers; }
-    inline const ClearBuffers* globalClearColorBuffers() const { return m_globalClearColorBuffer; }
+    inline QVector<ClearBufferInfo> specificClearColorBufferInfo() const { return m_specificClearColorBuffers; }
+    inline QVector<ClearBufferInfo> &specificClearColorBufferInfo() { return m_specificClearColorBuffers; }
+    inline ClearBufferInfo globalClearColorBufferInfo() const { return m_globalClearColorBuffer; }
+
     inline QClearBuffers::BufferTypeFlags clearTypes() const { return m_clearBuffer; }
     inline float clearDepthValue() const { return m_clearDepthValue; }
     inline int clearStencilValue() const { return m_clearStencilValue; }
@@ -249,8 +258,8 @@ private:
     QClearBuffers::BufferTypeFlags m_clearBuffer;
     float m_clearDepthValue;
     int m_clearStencilValue;
-    const ClearBuffers* m_globalClearColorBuffer;               // global ClearColor
-    QVector<const ClearBuffers*> m_specificClearColorBuffers;   // different draw buffers with distinct colors
+    ClearBufferInfo m_globalClearColorBuffer;               // global ClearColor
+    QVector<ClearBufferInfo> m_specificClearColorBuffers;   // different draw buffers with distinct colors
     RenderStateSet *m_stateSet;
     bool m_noDraw:1;
     bool m_compute:1;
diff --git a/src/render/framegraph/framegraphvisitor.cpp b/src/render/framegraph/framegraphvisitor.cpp
index 211ed0660..a27cca19f 100644
--- a/src/render/framegraph/framegraphvisitor.cpp
+++ b/src/render/framegraph/framegraphvisitor.cpp
@@ -319,10 +319,19 @@ void FrameGraphVisitor::visit(Render::FrameGraphNode *node)
             renderer->enqueueRenderView(rv, currentRenderViewIndex);
         };
 
+        auto setClearBufferDrawIndex = [=] () {
+            RenderView *rv = renderViewJob->renderView();
+            QVector<ClearBufferInfo> &clearBuffersInfo = rv->specificClearColorBufferInfo();
+            const AttachmentPack &attachmentPack = rv->attachmentPack();
+            for (ClearBufferInfo &clearBufferInfo : clearBuffersInfo)
+                clearBufferInfo.drawBufferIndex = attachmentPack.getDrawBufferIndex(clearBufferInfo.attchmentPoint);
+        };
+
         auto syncRenderViewCommandBuildingJob = GenericLambdaJobPtr<decltype(syncForRenderCommandBuilding)>::create(syncForRenderCommandBuilding);
         auto syncRenderViewInitializationJob = GenericLambdaJobPtr<decltype(syncRenderViewInitialization)>::create(syncRenderViewInitialization);
         auto syncRenderViewCommandBuildersJob = GenericLambdaJobPtr<decltype(syncRenderViewCommandBuilders)>::create(syncRenderViewCommandBuilders);
         auto syncFrustumCullingJob = GenericLambdaJobPtr<decltype(syncFrustumCulling)>::create(syncFrustumCulling);
+        auto setClearBufferDrawIndexJob = GenericLambdaJobPtr<decltype(setClearBufferDrawIndex)>::create(setClearBufferDrawIndex);
 
         // Set dependencies
         syncFrustumCullingJob->addDependency(renderer->updateWorldTransformJob());
@@ -331,6 +340,8 @@ void FrameGraphVisitor::visit(Render::FrameGraphNode *node)
         frustumCulling->addDependency(renderer->expandBoundingVolumeJob());
         frustumCulling->addDependency(syncFrustumCullingJob);
 
+        setClearBufferDrawIndexJob->addDependency(syncRenderViewInitializationJob);
+
         syncRenderViewInitializationJob->addDependency(renderViewJob);
 
         filterEntityByLayer->addDependency(syncRenderViewInitializationJob);
@@ -351,6 +362,7 @@ void FrameGraphVisitor::visit(Render::FrameGraphNode *node)
             syncRenderViewCommandBuildersJob->addDependency(renderViewCommandBuilder);
         }
         renderer->frameCleanupJob()->addDependency(syncRenderViewCommandBuildersJob);
+        renderer->frameCleanupJob()->addDependency(setClearBufferDrawIndexJob);
 
         // Add jobs
         m_jobs->push_back(renderViewJob);
@@ -363,6 +375,7 @@ void FrameGraphVisitor::visit(Render::FrameGraphNode *node)
         m_jobs->push_back(lightGatherer);
         m_jobs->push_back(syncRenderViewCommandBuildersJob);
         m_jobs->push_back(syncFrustumCullingJob);
+        m_jobs->push_back(setClearBufferDrawIndexJob);
 
         for (const auto materialGatherer : qAsConst(materialGatherers))
             m_jobs->push_back(materialGatherer);