The Lancelot system is an extension of the QTest unit test framework.
Its purpose is to help catch rendering regressions. It facilitates
rendering a suite of test scenes, and comparing the produced output
images with the images produced from a previous rendering run.

Here are instructions for running lancelot tests locally on your PC:

1. Build lancelot baselineserver.
- cd [your qt5 path]\qtbase\tests\baselineserver\src\
- qmake
- jom (or make or nmake)

2. Start lancelot baselineserver and leave it running.
- cd [your qt5 path]\qtbase\tests\baselineserver\bin\
- baselineserver.exe

3. With Qt Creator, open Quick3D lancelot tests project
(qtquick3d\tests\auto\quick3d_lancelot\quick3d_lancelot.pro)

4. In Creator Project Settings, set an environmental variable
"QT_LANCELOT_SERVER" to "127.0.0.1".

5. Run quick3d_lancelot for the first time and you should see many
"Baseline not found on server. New baseline uploaded." lines.
Baseline PNG images will be stored into path like:
C:\var\www\Other\tst_Quick3D\baselines\testRendering\

6. Apply your changes, fixes etc. and run quick3d_lancelot test again.
If rendering output doesn't change to better or worse, you should see
something like:
...
PASS   : tst_Quick3D::testRendering(view3d/RenderModeOverlay.qml)
PASS   : tst_Quick3D::testRendering(view3d/RenderModeRenderNode.qml)
PASS   : tst_Quick3D::testRendering(view3d/RenderModeTexture.qml)
PASS   : tst_Quick3D::testRendering(view3d/RenderModeUnderlay.qml)
PASS   : tst_Quick3D::cleanupTestCase()
Totals: 80 passed, 0 failed, 0 skipped, 0 blacklisted, 122662ms
********* Finished testing of tst_Quick3D *********