A few weeks ago I downloaded Vuforia 4 to try it out. This is my first time using Vuforia, so I don't know anything about previous versions.
I'm using the Android SDK and played around with the samples, and I noticed an apparent mistake in the sample code.
The MultiTargets sample uses a simple CubeObject to track a physical 3d cube. I modified the shaders to display diffuse lighting instead of the included yellow line texture, and that requires me to use the normals provided by the CubeObject. But it seems that the normal definitions do not fully correspond with the vertex definitions! Some normals are pointing the wrong way when compared with the vertex order.
Normally that error is not noticed because the sample itself does not actually use the normals. But when I modified it and relied on the normals it sure took me a long time to figure out that the model information was wrong, since I was trusting the official sample code to be correct. It would be great if you could fix that to spare others the same fate :-)
One more thing: I repeatedly found links to an alledged official Vuforia diffuse shading tutorial at https://developer.vuforia.com/forum/faq/android-how-can-i-apply-lighting-my-3d-model. That tutorial does not seem to exist anymore! Could you maybe make that available again? I feel that I could probably have saved a lot of time while figuring this out by myself. Thanks.