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revision 1.55 by jvk, Tue Feb 11 15:50:53 2003 UTC revision 1.56 by jvk, Tue Feb 11 16:52:48 2003 UTC
# Line 476  maintain readability. Line 476  maintain readability.
476  Implementation on the Gzz platform  Implementation on the Gzz platform
477  ==================================  ==================================
478    
479  The implementation of the link structure and the above visual tenchiques  The Gzz platform supports easy prototyping of the above link structure and
480  is easy on the Gzz platform because of several features.  visual tenchiques because of several features.
481    
482  First, the Xanadu[XXX] structure implemented on Gzz  First, the Gzz storage model (Storm[XXX]) provides globally unique
483  provides a way for specifying associations between parts  identities for the documents and structural nodes and
484  of documents. Furthermore ...  the Xanadu[XXX] structure implemented on Gzz is a convenient way
485  XXXidentity???  for specifying associations between parts of documents.
486    
487  Second, the Gzz view model provides a simple way of  Second, the Gzz view model provides a simple way of
488  specifying geometry and automatic animation between views.  specifying geometry and automatic animation between views.
489    A view contains coordinate systems and vobs.
490  A view, or a vobscene, contains coordinate systems and vobs.  Vob is a visual object that knows how to draw itself in
491  Vob is a "visual object" that knows how to draw itself using zero,  one or more coordinate systems (for example, a connection line
492  one, or more coordinate systems. For example, a text string  vob draws a line between the origins of two coordinate systems).
493  drawn starting at the unit square of a text coordinate system or  When the user moves from one view to another,
494  a connection line drawn between the origins of two coordinate systems.  the coordinate systems of the first view are
495  The reason for separate coordinate systems is that a scene  interpolated to the matching coordinate systems of the
496  can be animated by interpolating the coordinate systems.  following scene, resulting in smooth animation.
497    
498  The coordinate systems can be recursive so that one coordinate  Third, most source code changes yield immediate effect without rebuilding.
499  system is specified depending on another coordninate system.  Jython source files can be dynamically reloaded and most vobs
500  For example, the buoy coordinate system uses a transformation  are specified using a string that is dynamically compiled into an
501  from the anchor position to the buoy position on a circle using  OpenGL display list.
502  the origin of the focus coordinate system.  Despite this, the framerate is high, because the
   
 Each coordinate system has an identifier and a parent coordinate  
 system. When the user moves from one view to another,  
 the coordinate systems of the two vobscenes are matched.  
 Matching coordinate systems (with matching parents) are smoothly  
 interpolated resulting in smooth animation from an object in one  
 scene to the corresponding object in the other scene.  
 If an object only exists in one of the scenes, it appears or  
 disappears at the middle point of the animation.  
   
 Another important feature is the dynamic object model.  
 Jython source files can be dynamically reloaded, and many  
 vobs can be specified simply as a string that is dynamically  
 compiled to an OpenGL display list.  
 Despite the dynamic nature, the code runs fast, because the  
503  interpolation of coordinate systems and the actual rendering of vobs  interpolation of coordinate systems and the actual rendering of vobs
504  is performed by native C++ code.  is finally performed by native C++ code.
505    
506    
507  An example structure: a MEMEX-like view of recent hypertext and graphics articles  An example structure: a MEMEX-like view of recent hypertext and graphics articles

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