Eye positions are given in meters in the headset coordinate system in VR space. The origin is in the middle of the segment connecting eye centers, with X points right, Y points up, and Z points forward. Thus the left eye center position is always (-ipd/2, 0, 0) and the right one is (ipd/2, 0, 0). Each eye gaze direction is a normalized vector. Simple formulas can be used to express gaze vectors in angles, e.g., horizontal angle can be computed as atan(x/z), and vertical as atan(y/z). Knowing gaze ray origin and direction (vector), gaze position can be projected on any intersecting plane in VR space.