@article {12174, title = {Implementing a zooming User Interface: experience building Pad++}, journal = {Software: Practice and Experience}, volume = {28}, year = {1998}, month = {1998/08/01/}, pages = {1101 - 1135}, abstract = {We are investigating a novel user interface paradigm based on zooming, in which users are presented with a zooming view of a huge planar information surface. We have developed a system called Pad++ to explore this approach. The implementation of Pad++ is related to real-time 3D graphics systems and to 2D windowing systems. However, the zooming nature of Pad++ requires new approaches to rendering, screen management, and spatial indexing. In this paper, we describe the design and implementation of the Pad++ engine, focusing in particular on rendering and data structure issues. Our goal is to present useful techniques that can be adopted in other real-time graphical systems, and also to discuss how 2D zooming systems differ from other graphical systems. {\textcopyright} 1998 John Wiley \& Sons, Ltd.}, keywords = {3D graphics, animation, Pad++, real-time computer graphics, User Interface Management Systems (UIMS), windowing systems, zooming User Interfaces (ZUIs)}, isbn = {1097-024X}, doi = {10.1002/(SICI)1097-024X(199808)28:10<1101::AID-SPE190>3.0.CO;2-V}, url = {http://onlinelibrary.wiley.com/doi/10.1002/(SICI)1097-024X(199808)28:10<1101::AID-SPE190>3.0.CO;2-V/abstract}, author = {Bederson, Benjamin B. and Meyer,Jon} }