# Read the rotation matrix from Cardboard and update `world_camera`
	private fun update_from_head_tracker
	do
		var head_tracker = head_tracker
		if head_tracker == null then return

		head_tracker.last_head_view(java_rotation_matrix, 0)

		# Copy values from the Java array to our matrix
		for y in [0..4[ do
			for x in [0..4[ do
				world_camera.rotation_matrix[y, x] = java_rotation_matrix[y*4+x]
			end
		end
	end