[Xr] Default scaling matrix

Bill Spitzak spitzak at d2.com
Thu May 22 13:45:04 PDT 2003

On Thursday 22 May 2003 01:14 pm, Carl Worth wrote:

> I like this idea. The most simple thing to do might be to have an
> XrDefaultMatrixExact() that has the same basic scale factor as
> XrDefaultMatrix() but without the rounding. That way, as device
> resolution increases, the difference between XrDefaultMatrix and
> XrDefaultMatrixExact decreases.

Excellent idea. That gets rid of any question about what units to use. In the 
future people will be told that it was based on the common dot spacing used 
in CRT's in 2003, but that makes as much sense as the history for any other 
units of measurement.

> But, since XrIdentityMatrix is device-dependent in terms of the scale,
> it seems it should go all the way and be device-dependent in terms of
> the origin as well. In other words, XrIdentityMatrix should deliver as
> advertised and install a mathematical identity matrix, (no
> transformation of coordinates from user space to device space).

> Seem reasonable?

Sounds good to me. Anybody who wants to figure out the origin can do so by 
examining the Default matrix.

                   ,~,~,~,~ ~ ~ ~ ~
     /\_       _|_========___         Bill Spitzak
 ~~~/\/\\~~~~~~\____________/~~~~~~~~ spitzak at d2.com

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