| Re: Transformation of Objects and Models [message #61984 is a reply to message #61976] |
Mon, 18 August 2008 12:42   |
Rick Towler
Messages: 821
Registered: August 1998
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Senior Member |
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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
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