9 May
2013
9 May
'13
1:59 a.m.
On 8 May 2013 22:19, Alexandre Bergel <alexandre.bergel(a)me.com> wrote:
But don't be fooled by concrete (AthensAffineTransform) matrix.
In reality, Athens works with abstract "transform" object (AthensTransform)
i.e.
canvas pathTransform
or
canvas paintTransform
and while under the hood, things are run by matrices, i really
discourage you from
betting what kind of data they hold, and either they are 2x3 , 3x3 of
4x4 matrices.
This is backend-specific and not of your concern.
For that reason, the API prohibits you from directly accessing the
matrix state (i.e. get/set value at rowN columnM).
Instead there's operators (methods) which modifying transform e.g.
canvas pathTransform scaleBy:2
means that for all subsequent operations
canvas pathTransform will become the result of: (current canvas
pathTransform * scale matrix)
same for the rest operations.
For more details, look at AthensTransform class comment. It is a bit
outdated, but you will get an idea.
>> Your matrixes are 2x2 ? I thought they would
be 3x3, I haven't verified, by having 3x3 for 2d plans allows for zooming. But maybe
you do not need since Athens handles this apart.
>
well, matrix in athens is 2x3 affine matrix.
(consider it is like a full 3x3 matrix but with all zeros at bottom row)
simply because if you extend 2d vector to 3d, you put z-component to 0..
that means , if you multiply such vector with full 3x3 matrix,
the 3rd row will be completely ignored, because z-component does not
contributes to
x and y coordinates.
did you try
the code snippet of igor that I sent to the list?
Because you can zoom in a vector graphics polymetric view.
Well, I had a look at the code. The matrix of Athens are indeed small and neat.
Replacing this in Roassal is not trivial and cannot be done in a matter of a few
minutes.
Alexandre
--
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Alexandre Bergel http://www.bergel.eu
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--
Best regards,
Igor Stasenko.