SyncRenderViewPreCommandUpdate: fix a few odd cases

- We need to perform frustum culling even if camera hasn't moved as entities
  in the scene could still be moving
- We shouldn't return early if there's nothing to draw/or filter. Given we
  keep 2 sets of render command buffers we flip between every frame, we still
  need to update the command indices on bufferA, so that bufferB get initialized
  with values from bufferA at the end of the frame ...
  Otherwise in the case where at frame N (bufA) we have a visible object and at
  frame N+1 (bufB), that object is culled object. If we return early, bufB would
  never gets updated to contain 0 command indices. We would then end up
  flickering between visible and non visible object.

Change-Id: I248c54b89a3795fa69c23ea952424c68696313e1
Reviewed-by: Mike Krus <mike.krus@kdab.com>
(cherry picked from commit b76e9b0eccdd49a539e213a91bcaecbd98efbd74)

1 files changed, 8 insertions, 10 deletions

diff --git a/src/plugins/renderers/opengl/renderer/renderviewbuilder.cpp b/src/plugins/renderers/opengl/renderer/renderviewbuilder.cpp
index 32667dceb..41aef69a0 100644
--- a/src/plugins/renderers/opengl/renderer/renderviewbuilder.cpp
+++ b/src/plugins/renderers/opengl/renderer/renderviewbuilder.cpp
@@ -370,13 +370,15 @@ public:
                 // Record the updated viewProjectionMatrix in the cache to allow check to be performed
                 // next frame
                 cacheForLeaf.viewProjectionMatrix = rv->viewProjectionMatrix();
+            }
 
-                // Filter out frustum culled entity for drawable entities and store in cache
-                if (isDraw && rv->frustumCulling()) {
-                    cacheForLeaf.filteredAndCulledRenderables = RenderViewBuilder::entitiesInSubset(
-                                cacheForLeaf.layeredFilteredRenderables,
-                                m_frustumCullingJob->visibleEntities());
-                }
+            // Filter out frustum culled entity for drawable entities and store in cache
+            // We need to check this regardless of whether the camera has moved since
+            // entities in the scene themselves could have moved
+            if (isDraw && rv->frustumCulling()) {
+                cacheForLeaf.filteredAndCulledRenderables = RenderViewBuilder::entitiesInSubset(
+                            cacheForLeaf.layeredFilteredRenderables,
+                            m_frustumCullingJob->visibleEntities());
             }
 
             rv->setMaterialParameterTable(cacheForLeaf.materialParameterGatherer);
@@ -400,10 +402,6 @@ public:
             // Set RenderCommandDataView on RV (will be used later on to sort commands ...)
             rv->setRenderCommandDataView(filteredCommandData);
 
-            // Early return in case we have nothing to filter
-            if (renderableEntities.size() == 0)
-                return;
-
             // Filter out Render commands for which the Entity wasn't selected because
             // of frustum, proximity or layer filtering
             if (commandFilteringRequired) {