In this code, you can see sample point cloud and label it. Please clone this code and open index.html using FireFox. Or please check web site demo.
https://cpfl.github.io/3d_labeling_tools/
Click Bounding Box. You can see opening Bounding Box Tools(GUI Editor).
Click AddBoundingBox Button. You can add New Bounding Box.
Edit position(X, Y, Z, delta x, delta y, delta z) and scale(width, height, depth) on GUI Editor.
Edit position(X, Y, Z, delta x, delta y, delta z) and scale(width, height, depth) directly.
Push Shift and Drag to change 3D camera position. Push Shift and left or right to change 2D camera position. Push Shift and Scroll to go near or away.