-- returns the angle difference between pos1 and pos2, as seen from pos1 at the specified yaw and pitch
    local function pos_to_angle (pos1, pos2, yaw, pitch)
       -- note: we must invert the yaw for x in yaw_vec, to keep the result from inverting when facing opposite directions (0* becoming 180*)
       local yaw_vec = {x = math.sin(-yaw) * math.cos(pitch), y = math.sin(pitch), z = math.cos(yaw) * math.cos(pitch)}
       local pos_subtract = vector.subtract(pos2, pos1)
       local pos_dotproduct = (yaw_vec.x * pos_subtract.x) + (yaw_vec.y * pos_subtract.y) + (yaw_vec.z * pos_subtract.z)
       local angle = math.deg(math.acos(pos_dotproduct / (vector.length(yaw_vec) * vector.length(pos_subtract))))
       return angle
    end