REveTrans is a 4x4 transformation matrix for homogeneous coordinates stored internally in a column-major order to allow direct usage by GL.
The element type is Double32_t as statically the floats would be precise enough but continuous operations on the matrix must retain precision of column vectors.
Cartan angles are stored in fA[1-3] (+z, -y, +x). They are recalculated on demand.
Direct element access (first two should be used with care):
Column-vector access: USet Get/SetBaseVec(), Get/SetPos() and Arr[XYZT]() methods.
For all methods taking the matrix indices: 1->X, 2->Y, 3->Z; 4->Position (if applicable). 0 reserved for time.
Shorthands in method-names: LF ~ LocalFrame; PF ~ ParentFrame; IP ~ InPlace