| Re: selecting model objects [message #20788] |
Wed, 26 July 2000 00:00  |
Mark Hadfield
Messages: 783
Registered: May 1995
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Senior Member |
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"Rick Towler" <rtowler@u.washington.edu> wrote in message
news:397E213D.4C565D8@u.washington.edu...
> ...
> I require the ability to select individual models within a view and to
> translate them AS A GROUP.
>
> If I have model "A" which is a child (added to) model "B" within a view
> that is drawn to a window, will the select method return ALL of the
> models or just the parent model B? As my program is working now only
> model B is being returned even if I click on it's child model A.
Yes, if model B has its SELECT_TARGET property set then it "traps" selection
for all its children.
You shouldn't be thinking about "clicking on models". Models are containers
with a transformation matrix. They don't have any spatial extent. Sort of
like invisible elbow joints (for rotation) or zoom lenses (for scaling). I
like the zoom lens analogy better: you look *through* a model at its
children. The things you can click on are atoms. Models with the
SELECT_TARGET property set are a special case: they let you gather several
atoms together and make them all act like a single atom. But unless you're
building such a composite atom, I don't think you should be setting a
model's SELECT_TARGET property.
Perhaps what you need to do is work upwards through the graphics tree.
Having caught a selection on one of the atoms (or composite atoms) find the
model it is attached to via the atom's PARENT property. If you
scale/translate/rotate the parent then you affect the selected atom and all
its siblings. (Is that what you want to do? Or do you need to go further up
the tree?)
---
Mark Hadfield
m.hadfield@niwa.cri.nz http://katipo.niwa.cri.nz/~hadfield/
National Institute for Water and Atmospheric Research
PO Box 14-901, Wellington, New Zealand
> If in theory the select method can return an array of models (all of the
> children models plus the parent model) any ideas why the child model
> information isn't trickling down? The /SELECT_TARGET keyword is set on
> both models.
>
>
> Adding model "A" and model "B" directly to the view does allow for
> selection of individual models. But, this approach requires that I keep
> track of all of the models in the view and translate them individually
> when one of them is selected to move.
>
> I guess I have a solution but I am still curious. Has anybody tried
> using the select method to select child models within a parent model?
> Is this just impossible?
>
>
> Thanks all!
>
> -Rick Towler
>
>
>> Rick Towler (rtowler@u.washington.edu) writes:
>>
>>> I have a base model (a map) that contains other models (geographic
>>> data). I need to select data within the map using the IDLgrWindow
>>> Select method. Right now I am only getting the base model returned.
>>>
>>> object heirarchy is: [data_model]->[map_model]->[oView]->[oWindow]
>>>
>>> ; my select code
>>> item = oWindow->Select(oView, [event.x, event.y])
>>>
>>> item contains the reference to map_model only.
>>>
>>> A key point is that I need to anchor the geographic data to the map
and
>>> I need to be able to translate and scale the map. Because of this I
>>> haven't been able to add the data objects directly to the view since
>>> each of the objects would translate/scale independently and the
>>> geographic data would be dereferenced from the underlying map.
>>>
>>> is it possible to select a model (or atom) that is contained in
another
>>> model that is contained in a view?
>>>
>>> If not, is there a way to "join" 2 or more models so when translating
or
>>> scaling they behave as 1?
>>
>> To make a model object "selectable" you must first set
>> its SELECT_TARGET keyword. The Select method should then
>> return an array of selected objects located under the
>> selection point.
>>
>> Cheers,
>>
>> David
>>
>> --
>> David Fanning, Ph.D.
>> Fanning Software Consulting
>> Phone: 970-221-0438 E-Mail: davidf@dfanning.com
>> Coyote's Guide to IDL Programming: http://www.dfanning.com/
>> Toll-Free IDL Book Orders: 1-888-461-0155
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