Renderer: cache traversal of FrameGraph

Will be retraversed only when something in the FrameGraph has changed

Change-Id: Ibb43f8f2928b10a584f468fb13f1d4773c7fcebb
Reviewed-by: Mike Krus <mike.krus@kdab.com>

3 files changed, 40 insertions, 36 deletions

diff --git a/src/render/renderers/opengl/renderer/renderer.cpp b/src/render/renderers/opengl/renderer/renderer.cpp
index af9a6e7e6..66d404f4e 100644
--- a/src/render/renderers/opengl/renderer/renderer.cpp
+++ b/src/render/renderers/opengl/renderer/renderer.cpp
@@ -1824,26 +1824,27 @@ QVector<Qt3DCore::QAspectJobPtr> Renderer::renderBinJobs()
         // populate the RenderView with a set of RenderCommands that get
         // their details from the RenderNodes that are visible to the
         // Camera selected by the framegraph configuration
-        FrameGraphVisitor visitor(m_nodesManager->frameGraphManager());
-        const QVector<FrameGraphNode *> fgLeaves = visitor.traverse(frameGraphRoot());
-
-        // Handle single shot subtree enablers
-        const auto subtreeEnablers = visitor.takeEnablersToDisable();
-        for (auto *node : subtreeEnablers)
-            m_updatedDisables.push_back(node->peerId());
-        if (m_updatedDisables.size() > 0)
-            renderBinJobs.push_back(m_sendDisablesToFrontendJob);
-
-        // Remove leaf nodes that no longer exist from cache
-        const QList<FrameGraphNode *> keys = m_cache.leafNodeCache.keys();
-        for (FrameGraphNode *leafNode : keys) {
-            if (!fgLeaves.contains(leafNode))
-                m_cache.leafNodeCache.remove(leafNode);
+        if (frameGraphDirty) {
+            FrameGraphVisitor visitor(m_nodesManager->frameGraphManager());
+            m_frameGraphLeaves = visitor.traverse(frameGraphRoot());
+            // Remove leaf nodes that no longer exist from cache
+            const QList<FrameGraphNode *> keys = m_cache.leafNodeCache.keys();
+            for (FrameGraphNode *leafNode : keys) {
+                if (!m_frameGraphLeaves.contains(leafNode))
+                    m_cache.leafNodeCache.remove(leafNode);
+            }
+
+            // Handle single shot subtree enablers
+            const auto subtreeEnablers = visitor.takeEnablersToDisable();
+            for (auto *node : subtreeEnablers)
+                m_updatedDisables.push_back(node->peerId());
+            if (m_updatedDisables.size() > 0)
+                renderBinJobs.push_back(m_sendDisablesToFrontendJob);
         }
 
-        const int fgBranchCount = fgLeaves.size();
+        const int fgBranchCount = m_frameGraphLeaves.size();
         for (int i = 0; i < fgBranchCount; ++i) {
-            RenderViewBuilder builder(fgLeaves.at(i), i, this);
+            RenderViewBuilder builder(m_frameGraphLeaves.at(i), i, this);
             builder.setLayerCacheNeedsToBeRebuilt(layersCacheNeedsToBeRebuilt);
             builder.setRenderableCacheNeedsToBeRebuilt(renderableDirty);
             builder.setComputableCacheNeedsToBeRebuilt(computeableDirty);
diff --git a/src/render/renderers/opengl/renderer/renderer_p.h b/src/render/renderers/opengl/renderer/renderer_p.h
index 0ea27d91a..c7b4f8805 100644
--- a/src/render/renderers/opengl/renderer/renderer_p.h
+++ b/src/render/renderers/opengl/renderer/renderer_p.h
@@ -424,6 +424,8 @@ private:
     QMetaObject::Connection m_contextConnection;
     RendererCache m_cache;
     bool m_shouldSwapBuffers;
+
+    QVector<FrameGraphNode *> m_frameGraphLeaves;
 };
 
 } // namespace Render
diff --git a/tests/auto/render/renderer/tst_renderer.cpp b/tests/auto/render/renderer/tst_renderer.cpp
index 973192d6a..e1bf8dfd9 100644
--- a/tests/auto/render/renderer/tst_renderer.cpp
+++ b/tests/auto/render/renderer/tst_renderer.cpp
@@ -36,6 +36,7 @@
 #include <Qt3DRender/private/renderviewbuilder_p.h>
 #include <Qt3DRender/private/offscreensurfacehelper_p.h>
 #include <Qt3DRender/private/renderqueue_p.h>
+#include <Qt3DRender/private/job_common_p.h>
 
 class tst_Renderer : public QObject
 {
@@ -170,9 +171,24 @@ private Q_SLOTS:
         //                   syncRenderViewCommandBuilderJob
         //                   n * (RenderViewCommandBuildJobs)
 
-        // WHEN (nothing dirty, no buffers, no layers to be rebuilt, no materials to be rebuilt)
+        // WHEN
         QVector<Qt3DCore::QAspectJobPtr> jobs = renderer.renderBinJobs();
 
+        // THEN
+        QCOMPARE(jobs.size(),
+                 1 + // updateLevelOfDetailJob
+                 1 + // cleanupJob
+                 1 + // VAOGatherer
+                 1 + // updateSkinningPaletteJob
+                 1); // SyncLoadingJobs
+
+        renderer.clearDirtyBits(Qt3DRender::Render::AbstractRenderer::AllDirty);
+        renderQueue->reset();
+
+        // WHEN (nothing dirty, no buffers, no layers to be rebuilt, no materials to be rebuilt)
+        renderer.markDirty(Qt3DRender::Render::AbstractRenderer::FrameGraphDirty, nullptr);
+        jobs = renderer.renderBinJobs();
+
         // THEN (level
         QCOMPARE(jobs.size(),
                  1 + // updateLevelOfDetailJob
@@ -180,7 +196,9 @@ private Q_SLOTS:
                  1 + // VAOGatherer
                  1 + // updateSkinningPaletteJob
                  1 + // SyncLoadingJobs
-                 singleRenderViewJobCount); // Only valid for the first call to renderBinJobs(), since subsequent calls won't have the renderqueue reset
+                 singleRenderViewJobCount +
+                 renderViewBuilderMaterialCacheJobCount +
+                 layerCacheJobCount);
 
         renderer.clearDirtyBits(Qt3DRender::Render::AbstractRenderer::AllDirty);
         renderQueue->reset();
@@ -298,23 +316,6 @@ private Q_SLOTS:
         renderQueue->reset();
 
         // WHEN
-        renderer.markDirty(Qt3DRender::Render::AbstractRenderer::FrameGraphDirty, nullptr);
-        jobs = renderer.renderBinJobs();
-
-        QCOMPARE(jobs.size(),
-                 1 + // updateLevelOfDetailJob
-                 1 + // cleanupJob
-                 1 + // VAOGatherer
-                 1 + // updateSkinningPaletteJob
-                 1 + // SyncLoadingJobs
-                 singleRenderViewJobCount +
-                 layerCacheJobCount +
-                 renderViewBuilderMaterialCacheJobCount);
-
-        renderer.clearDirtyBits(Qt3DRender::Render::AbstractRenderer::AllDirty);
-        renderQueue->reset();
-
-        // WHEN
         renderer.markDirty(Qt3DRender::Render::AbstractRenderer::AllDirty, nullptr);
         jobs = renderer.renderBinJobs();