6 May
2013
6 May
'13
1:26 p.m.
Igor did not want to send them because he does not
want to look like an asshole criticizing but I think that if we want roassal to be really
a success we should.
Sure, making this email public is the best to do. As researchers we should embrace
feedback, even if not positive.
* Point 1: wasting cycles to do conversion
--------------------------------------------------------
ROPharoCanvas>>line: aPoint to: aPoint2 width: aSmallInteger color: aColor
nativeCanvas line: (self virtualToRealPoint: aPoint) to: (self virtualToRealPoint:
aPoint2) width: aSmallInteger color: aColor.
wasting cycles to convert from your local coordinate space into global one on every
single operation is not a good idea. Guess why :)
Athens provides the user-space coordinate system for geometry by default.. so that you
don't have to maintain it by yourself.
So if you want a real system these points should be addressed ;)
Maintaining virtual coordinates is essential for zooming and scrolling the whole view.
Athens has indeed fast primitives to do this. We will probably consider using them this
once Athens will be part of Pharo.
* Point 2: missing transformation matrix
-----------------------------------------------------
You don't even have a transformation as a concept.. and instead of simple and
straightforward affine matrix which people
learn in schools today: a Camera
[ ... ]
see this #virtualToRealPoint: calls?
Athens provides this for free. Do not do it the hard way: (do not transform poor vector
multiple times to get there.)
Athens do it for you using math:
(v * M1) * M2 = v * (M1*M2)
We thought about using matrixes. And the nice things is to be able to do rotation, thing
that we cannot do right now in Roassal because we do not have matrixes. We are wondering
whether we should wait for Athens to be part of Roassal to use matrix or doing it our
way.
By the way, using a matrix implies more operations that Roassal actually does, because
doing v * M has more operations than the method #virtualToRealPoint:. However this does
not really matter since this is rather cheap.
* Point 3 about design
------------------------------
ROAbstractArrow
ROArrow
ROReversedArrow
ROHorizontalArrow
ROReversedHorizontalArrow
ROVerticalArrow
ROReversedVerticalArrow
Why do we have all these classes? why they are not...
... traits? Well... because there is little support in Pharo to work with traits.
Another reason is traits exist only in Pharo.
Cheers,
Alexandre
--
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Alexandre Bergel http://www.bergel.eu
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