Make Gazebo aware of SetCameraPassCountPerGpuFlush (gazebosim#921)

* Call Scene::PostRenderGpuFlush

Requires ign-rendering update to compile correctly

Affects gazebosim/gz-rendering#323

Signed-off-by: Matias N. Goldberg <dark_sylinc@yahoo.com.ar>

* Update to use the renamed PostRender call

Signed-off-by: Matias N. Goldberg <dark_sylinc@yahoo.com.ar>

* Avoid warnings from Legacy mode

Signed-off-by: Matias N. Goldberg <dark_sylinc@yahoo.com.ar>

* Default to SetNumCameraPassesPerGpuFlush = 6

Signed-off-by: Matias N. Goldberg <dark_sylinc@yahoo.com.ar>

* Rename SetNumCameraPassesPerGpuFlush -> SetCameraPassCountPerGpuFlush

Signed-off-by: Matias N. Goldberg <dark_sylinc@yahoo.com.ar>

* Style changes

Signed-off-by: Matias N. Goldberg <dark_sylinc@yahoo.com.ar>
Signed-off-by: William Lew <WilliamMilesLew@gmail.com>

src/gui/plugins/scene3d/Scene3D.cc

@@ -1881,6 +1881,8 @@ void IgnRenderer::Initialize()
 
   auto root = scene->RootVisual();
 
+  scene->SetCameraPassCountPerGpuFlush(6u);
+
   // Camera
   this->dataPtr->camera = scene->CreateCamera();
   root->AddChild(this->dataPtr->camera);

src/systems/sensors/Sensors.cc

@@ -196,6 +196,7 @@ void SensorsPrivate::WaitForInit()
       igndbg << "Initializing render context" << std::endl;
       this->renderUtil.Init();
       this->scene = this->renderUtil.Scene();
+      this->scene->SetCameraPassCountPerGpuFlush(6u);
       this->initialized = true;
     }
 
@@ -262,6 +263,15 @@ void SensorsPrivate::RunOnce()
       // publish data
       IGN_PROFILE("RunOnce");
       this->sensorManager.RunOnce(this->updateTime);
+    }
+
+    {
+      IGN_PROFILE("PostRender");
+      // Update the scene graph manually to improve performance
+      // We only need to do this once per frame It is important to call
+      // sensors::RenderingSensor::SetManualSceneUpdate and set it to true
+      // so we don't waste cycles doing one scene graph update per sensor
+      this->scene->PostRender();
       this->eventManager->Emit<events::PostRender>();
     }