[cairo] The right approach to projective transformations

Maarten Bosmans mkbosmans at gmail.com
Tue Aug 31 11:43:33 PDT 2010

2010/8/31 Behdad Esfahbod <behdad.esfahbod at gmail.com>:
> On 08/31/10 13:52, Bill Spitzak wrote:
>> Behdad Esfahbod wrote:
>>> Right.  But we should be careful not adding yet another space.
>>> cairo_user_to_device_distance() will suffer no matter what.
>> I think this will have to return the device distance between the
>> transforms of 0,0 and x,y.
>> Or maybe the current point and the current point plus x,y?
> I kinda like that.

Yes, but it should be clear from the documentation that once the
projective parts of the transformation matrix are non-zero the notion
of translational invariance is gone and the concept of distance is
dependent on where you are on the surface.


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