One of the tricks I am still trying to decode using ARKit is to figure out how to determine the camera angle - not the rotation - but the pure up/down angle: e.g., +90˚ looking at the ceiling, -90˚ looking at the floor; 0˚ straight ahead - from the Euler angles or the camera tranform matrix. Sadly my college linear algebra classes were quite a long time ago which might be part of the problem 😊 ...
In essence I would like to be able to place objects that are visible (for example) when looking up at wall or with some other very specific angular placement.
Anyone else tackled this?