Scene3D: halt Qt3D simulation loop while not visible

Change-Id: I09d69fab7aaf3c2fa77da6eb30e505d9cb25c01f
Reviewed-by: Mike Krus <mike.krus@kdab.com>

1 files changed, 11 insertions, 0 deletions

diff --git a/src/quick3d/imports/scene3d/scene3ditem.cpp b/src/quick3d/imports/scene3d/scene3ditem.cpp
index 835485385..55e972406 100644
--- a/src/quick3d/imports/scene3d/scene3ditem.cpp
+++ b/src/quick3d/imports/scene3d/scene3ditem.cpp
@@ -137,6 +137,11 @@ namespace Qt3DRender {
     \li The Scene3D instance is instantiated prior to any Scene3DView
     \li The Scene3D entity property is left unset
     \endlist
+
+    \note Śetting the visibility of the Scene3D element to false will halt the
+    Qt 3D simulation loop. This means that binding the visible property to an
+    expression that depends on property updates driven by the Qt 3D simulation
+    loop (FrameAction) will never reavaluates.
  */
 Scene3DItem::Scene3DItem(QQuickItem *parent)
     : QQuickItem(parent)
@@ -455,6 +460,12 @@ bool Scene3DItem::needsRender()
 // processFrame will block and wait for renderer to have been finished
 void Scene3DItem::onBeforeSync()
 {
+    // If we are not visible, don't processFrame changes as we would end up
+    // waiting forever for the scene to be rendered which won't happen
+    // if the Scene3D item is not visible
+    if (!isVisible())
+        return;
+
     // Has anything in the 3D scene actually changed that requires us to render?
     if (!needsRender())
         return;