Let's see if this helps with blank output

wonder-sk · wonder-sk · commit db5106253ecf · 2018-07-26T08:34:38.000+02:00
diff --git a/tests/src/3d/testqgs3drendering.cpp b/tests/src/3d/testqgs3drendering.cpp
@@ -128,6 +128,8 @@ void TestQgs3DRendering::testFlatTerrain()
   // look from the top
   scene->cameraController()->setLookingAtPoint( QgsVector3D( 0, 0, 0 ), 2500, 0, 0 );
   QImage img = Qgs3DUtils::captureSceneImage( engine, scene );
+  QTest::qSleep( 1000 );
+  img = Qgs3DUtils::captureSceneImage( engine, scene );
   QVERIFY( renderCheck( "flat_terrain_1", img, 40 ) );
 
   // tilted view (pitch = 60 degrees)
