[Ipe-discuss] Isometric circles in IPE

Alexander Wolff alexander.wolff at uni-wuerzburg.de
Wed Jun 1 09:50:16 CEST 2011


hi villads & otfried,

what about shearing?  would that solve the circle -> ellipse problem?

the user interface could be to select a line and then to click at an 
arbitrary point of the canvas and move it with the mouse button pressed. 
  the move may be restricted to be parallel to the line.

i think this would be a helpful operation independently of the circle / 
ellipse issue.

sascha



On 06/01/2011 03:05 AM, Otfried Cheong wrote:
> On 06/01/2011 02:15 AM, Villads wrote:
>> Thank you for a very nice editor! Does anybody knows of a good way to
>> draw isometric circles in IPE? The easiest way would be if one could
>> just draw a circle inside a square an then transform the square and
>> circle into its isometric equivalent, but as far as I can find out, the
>> stretch-function only does stretching in one direction at a time?
>
> An isometric transformation of a circle is still a circle - I guess you
> mean affine transformations? So the question is really on what is the
> best way to draw ellipses, and I agree that I haven't really found the
> best way yet.
>
> The normal way is to draw a circle, then stretch it, and finally rotate
> it. Stretch does stretch in both directions at the same time, but only
> axis-parallel - such a restriction is unavoidable as the mouse has only
> two degrees of freedom.
>
> However, sometimes this is not the best way to draw an ellipse, but I
> know no better general interface. It would be nice to have a tool that
> takes the two foci and a third point, but that is still often not the
> right approach.
>
> Cheers,
> Otfried
>
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