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Re: Transformation of Objects and Models [message #62068 is a reply to message #61976] Tue, 19 August 2008 07:37 Go to previous message
Erik[1] is currently offline  Erik[1]
Messages: 23
Registered: December 2006
Junior Member
On 19 aug, 14:16, Erik <jansse...@gmail.com> wrote:
> On 18 aug, 21:42, Rick Towler <rick.tow...@nomail.noaa.gov> wrote:
>
>
>
>> ben.bighair wrote:
>>> On Aug 18, 6:37 am, Erik wrote:
>>>> Hi all,
>
>>>> I'm working on a piece of code to make the handling of IDLgr objects a
>>>> lot easier (IDL 6.3). The goal is to easily select some visual objects
>>>> like ROI's, Lines and Text and move / resize or rotate them in the
>>>> drawwidget.
>
>>>> I used the translate/rotate/scale functions of the IDLgrROI / IDLanROI
>>>> object a lot and it does exactly what it's supposed to do. But
>>>> unfortunately the other IDLgr objects (like; IDLgrPolyLine, IDLgrText)
>>>> does not have the transformation functions that the ROI object has :-
>>>> ( . For example, to move a polyline, I cannot use the code oLine->Translate, tx, ty. Instead I must retrieve and alter the DATA
>
>>>> property. To move a IDLgrText object, this must be done with the
>>>> LOCATION property... and so forth.
>
>>>> To make things easier I expected the IDLgrModel object to supply the
>>>> solution for me, because the model has the same transformation
>>>> functions as a ROI. At first glance, it seems to work. When I add a
>>>> line to a model and give a translate command, the line get moved as
>>>> expected. Same story for IDLgrText and IDLgrROI objects, so I suppose
>>>> this works for any object that can be added to a model.
>
>>>> My complaint however, is that the actual DATA of the IDLgr Objects
>>>> stays the same! When I move a line to the right on my window, I also
>>>> want the Object's X-data to be changed! It seems like the
>>>> transformation of the Model does not do this :-( .
>
>>>> I can understand if the Model is not meant to change this data, but
>>>> why doesn't have all IDLgr objects the same commands for
>>>> transformation?
>
>> Because you are supposed to stick those objects in models and not
>> transform them by altering their underlying data. :)  If you mean to
>> drag around your graphic objects by changing their underlying data
>> values I foresee headaches and unreasonably slow and complicated code in
>> your future.
>
>> The usual approach would be to stick every movable object in its own
>> model.  Transform the model and forget about the object's underlying
>> data.  If for some reason after dragging your object just so, you need
>> to extract the transformed vertices you can get the model's
>> transformation and apply that to the verts yourself.
>
>> -Rick
>
> Thanks for your reply's. The reason why I wanted to alter the
> underlying data, is because the property's of the objects will be used
> for the rest of the program. For example, the number of counts in a
> ROI will be different if the ROI is placed elsewhere on the widget.
> Same goes for lines, which can be used to determine a start of an
> analysis over a linogram. Guess I'll need to extract the model
> tranformation then!

I have one more question;
How can I use a transform matrix of a model (which describes a
rotation), to rotate the DATA of an IDLgrPolyline object?
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