Project Looking Glass
Demonstrating existing 2D applications and a 3D CD selector demo application are coexisting inside the 3D desktop environment
|Stable release||1.0.1 / January 29, 2007|
|License||GNU General Public License|
Looking Glass is programmed in the Java language using the Java 3D system to remain platform independent. Despite the use of graphics acceleration features, the desktop explores the use of 3D windowing capabilities for both existing application programs and ones specifically designed for Looking Glass.
Looking Glass was first developed by Hideya Kawahara, a Sun programmer who wrote it in his spare time on a small Linux laptop. After demonstrating an early version to Sun executives, he was assigned to it full-time with a dedicated team and open-sourced the project.  It was first demonstrated publicly by Jonathan Schwartz at LinuxWorld Expo 2003 in San Francisco, and since then has gathered momentum in development. After unveiling the prototype, Steve Jobs called Schwartz's office and told him that Apple would sue Sun if Sun moved forward to commercialize it. Jobs claimed that the project is infringing Apple's IP.  Regardless of the threat, Sun determined that the project was not of priority and decided not to put more resource to develop it further into product quality. The project thus had been continuing in an experimental mode. However, as Sun's financial situation became tighter and the management determined they had higher priority projects on their hand, the project became inactive (practically dead) since late 2006. 
One of its most notable features is the creation of reversible windows. This capability can be used for features like allowing the user to write notes and comments on the windows' backs, or displaying application dialogs without risking their being detached from the application they relate to. All windows start by looking like a normal 2D or 2.5D window, but can be manipulated as thin slate-like 3D objects which can be set at any angle or turned completely around by the user.
Other features include tilting all the window to assist the user to pick up a desired window, provision of a panning virtual desktop, icons that reflect the live status of the window they represent and zooming of a window when it receives focus.
There are a few designs that Looking Glass implemented and appeared in other products in later years. One technique became popular by Apple's Dashboard widgets is configuration of an application (widget) by flipping its visual and performing updates on the backside of it. The visual of Apple's Mac OS X Dock became similar to Looking Glass's look when Leopard was released.  Microsoft Windows 7 implements a feature for window selection that hides other windows than the one that the user placed the mouse cursor on a thumbnail above the taskbar. It resembles Looking Glass's usage of transparency for window selection using window thumbnails on the taskbar. 
Similar projects 
Looking Glass is similar to the TaskGallery prototype from Microsoft Research and the open source Croquet project based on Squeak in terms of allowance for the user to manipulate applications (including existing 2D applications) in a 3D space. However, user interaction models of TaskGallery and Croquet are base on Virtual Reality-like experience where the user moves inside the 3D space to perform tasks, whereas Looking Glass retains the operational model of today's desktop (i.e. no walking around inside the 3D space) and uses 3D effects selectively where they are thought to be effective. Also, these three are similar as they are meant to work on adapted or enhanced versions of existing desktops rather than re-designing the entire graphical user interface from scratch, an approach taken by many Zooming User Interface projects such as the one created by the late Jef Raskin.
While many window managers (such as Microsoft's Desktop Window Manager, the X Window System based Compiz, and Mac OS X through Core Animation) can utilize 3D effects, these merely augment a conventional 2D environment.
See also 
- "Sun Opens Its 3-D 'Looking Glass' Linux Desktop". eWEEK.
- Granular Linux Documentation
- Schwartz, Jonathan (March 9, 2010). "Good Artists Copy, Great Artists Steal".
- Kawahara, Hideya (September 18, 2009). "Announcement: INACTIVE (PRACTICALLY DEAD) since late 2006".
- "Leopard dock resembles Sun's Project Looking Glass?". June 12 2007.
- "Project Looking Glass: A Comprehensive Overview of the Technology". March 14, 2006.
- Official Demo Video on Youtube
- Another demo movie clip on Youtube - Without marketing speeches, but in lower quality.
- Project Looking Glass: A Comprehensive Overview of the Technology[dead link]
- Development home[dead link]
- LG3D Live CD[dead link]
- Interview with Hideya Kawahara