/[gzz]/gzz/Documentation/Manuscripts/Paper/paper.tex
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revision 1.95 by tjl, Fri Nov 29 10:39:46 2002 UTC revision 1.96 by tjl, Fri Nov 29 10:50:54 2002 UTC
# Line 647  of one or two types. Line 647  of one or two types.
647    
648  \subsection{Texture coordinates}  \subsection{Texture coordinates}
649    
650  Texture coordinates define the mapping of the basis textures to the background.  Texture coordinates define the mapping of the basis textures
651  Each basis texture is repeating, but by choosing the texture coordinates  to the coordinates of the final background texture.
 appropriately we can make the final background repeating or not.  
 If the paper will be used only at relatively few magnifications, it is  
 useful to use a repeating paper because of saving bits.  
 % XXX: explain  
 On the other hand, for user interfaces where zooming at widely different  
 scales is desirable, a non-repeating paper can be better.  
 % XXX: why is that?  
   
 % XXX: define repeating unit  
 In order to create more interesting backgrounds, it can also be useful  
 to use repeating units for non-repeating backgrounds --- but use more than one,  
 which are not rationally related.  
   
652  The choice of the repeating unit fixes an absolute scale to the paper.  The choice of the repeating unit fixes an absolute scale to the paper.
653  The repeating unit should be relatively isotropic to avoid  The repeating unit should be relatively isotropic to avoid
654  the degeneration of textures to diagonal lines.  the degeneration of textures to diagonal lines.
655    We choose the repeating unit from a heuristic distribution
656    created from these criteria.
657    
658  After a repeating unit is fixed, there is still  After a repeating unit is fixed, there is still
659  freedom in choosing  freedom in choosing
660  texture coordinates for each texture  texture coordinates for each texture
661  unit: any mapping of the texture is fine, as long as it repeats  unit: any mapping of the texture is fine, as long as it repeats
662  with the selected repeating unit.  with the selected repeating unit. For example, a texture can
663  % this is unclear  repeat multiple times inside the repeating unit, or can be skewed
664    w.r.t.~the repeating unit. These are also randomly chosen
665    from an ad hoc distribution.
666    
667  \subsection{Register combiners}  \subsection{Register combiners}
668    
# Line 855  be interesting to apply the same criteri Line 846  be interesting to apply the same criteri
846  The algorithms can be further developed: simulating lighting and  The algorithms can be further developed: simulating lighting and
847  a rough surface could produce good results.  a rough surface could produce good results.
848    
849    %
850    % Each basis texture is repeating,
851    % but by choosing the texture coordinates
852    % appropriately we can make the final background repeating or not.
853    % If the paper will be used only at relatively few magnifications, it is
854    % useful to use a repeating paper because of saving bits.
855    % % XXX: explain
856    % On the other hand, for user interfaces where zooming at widely different
857    % scales is desirable, a non-repeating paper can be better.
858    % % XXX: why is that?
859    
860    % % XXX: define repeating unit
861    In order to create more interesting backgrounds, it can also be useful
862    to use repeating units for non-repeating backgrounds --- but use more than one,
863    which are not rationally related.
864    
865    
866  \section{MPEG Animation}  \section{MPEG Animation}
867  [not to be included in final ms.]  [not to be included in final ms.]
868    

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