rotation order

Sander Koning sanderkoning at kde.nl
Sun Sep 18 13:53:44 CEST 2005


Thomas Zander wrote on 2005-09-18 13:08 +0200 regarding rotation order:
> The two rotate buttons on the toolbar of krita are logically ordered, 
> first the 90 and than the 270 one.
> After clicking wrongly twice I started wondering why I naturally clicked 
> the wrong ones;  and I think that they should be reversed (for the 270, 
> then the 90).
> 
> I'm still having headaces generally feeling sick (since 4 days now..) so I 
> don't want to draw conclusions which I currently can't even 
> rationalize :-(
> Can someone check the ordering in other applications? IIRC Gimp does do 
> the 270 (= 90CW) first in their menu.
> 
> Thanks.
> -- 
> Thomas Zander

GIMP has the order 90 degrees CW, 90 degrees CCW, 180 degrees in their menu. So
that's 270, 90, 180.

Rotating right is the more common thing for people to do in their daily lifes, I
think. Clockwise is rotating right, playing games typically uses a CW order (you
pass the turn to the one left of you), etcetera.

For mathematicians however (and in this context I consider myself to be one,
though mathematicians will object to that), rotating counterclockwise is normal
behaviour. Rotating 90 degrees is a turn left, rotating 270 degrees is a turn
right, therefore.

Checking my Krita installation (svn, say about a week old) I notice that Krita
uses what I would call a left-hand rotation system. In layman terms: the
rotations are done the ather way around. So the "Rotate 90" button does a 90
degrees CW rotation, which is what mathematicians would call a 270 degrees
rotation. Similarly, "Rotate 270" does a 90 degrees CCW rotation (90 degrees in
maths contexts). In other words, Krita does its rotations in the opposite
direction compared to what I'm used to.

At least the button icon properly reflects the behaviour (so I do choose the
right action by looking at the icons), but it's still not common behaviour, I'd
say. (And I'm not looking forward to having to mention "If you're used to rotations
from computer graphics contexts, then please note that Krita rotates the other
way around" when describing this in the documentation.)

My suggestion is to either change to right-hand rotation (i.e. 90 = 90 CW, 270
= 90 CCW), or ditch  the 90 and 270 (in the menus and toolbars) and call it CW
and CCW entirely. The Rotate {Image, Layer} dialogs offer both counterclockwise
and clockwise rotations, so there's no reason for confusion there. Calling a CCW
rotation 270 degrees however, is really counter-intuitive for anyone acquainted
with computer graphics, and rotation in particular.

Cheers,

-- 
Sander Koning                       |   sanderkoning - at - kde -.- nl
Documentation coordinator, KDE-NL   |   Documentation maintainer, Krita
http://www.kde.nl/                  |   http://koffice.org/krita/
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