Rotscrnang
Rotscrnang is the roll angle, i.e. the rotation around the axis pointing in the viewing direction.
Positive values rotate the view counter-clockwise, negative ones rotate it clockwise from the base angle.
Because the offset is reset towards 0 at a rate proportional to itself (currently hardcoded to one half), there is a point where the constant addition per time unit (+- 24, unless overridden by EVENT_LOOKLEFT/EVENT_LOOKRIGHT) and the resetting balance each other out.
example:
To emulate LOOKLEFT, subtract 152 from look_ang, and add 24 to rotscrnang.