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 |
|
|
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 |
|
|