I'm starting with Android VR-Toolkit for google cardboard. I use the sample at google website: https://developers.google.com/cardboard/get-started
I new with openGL and try to figure out how the values are represented by the system. For example HeadTransform.getHeadView set a 4x4 matrix and according to the documentation:
A matrix representing the transform from the camera to the head. Head origin is defined as the center point between the two eyes.
My question is what represents every value (each cell) in the matrix?