[vtkusers] Picking and Annotation

[Karthik Krishnan]

On Wed, Jan 27, 2010 at 12:00 PM, Rakesh Patil <rakeshthp at in.com> wrote:
>
> HI..
>
> Thanks to all for your replies..
>
> To David Gobbi,
> I want it just to highlight the cell so that next time again when user
> clicks some other cell,
> then, the current cell, which is highlighted ( or which is black), should
> become white and
> the newly selected cell, must be highlighted.
>
> I also thought the same thing, but, later on i thought, that we need to use
> two actors. and
> i guess, it can be done with one.. So just to find whether there is any
> possibility that this task
> can be achieved by using single actor or not,

Yes it can, by adding a dataarray containing scalars for cell data.
And then having the polydata colored by cell data. But this is a
terrible overkill to color just one cell. You should really use 2
actors.

> i posted my question.
> Nevertheless, i'll tr to implement this first.
>
> Thanks.
>
> ---------- Original message ----------
> From:Karthik Krishnan< karthik.krishnan at kitware.com >
> Date: 27 Jan 10 22:07:21
> Subject: Re: [vtkusers] Picking and Annotation
> To: Rakesh Patil
>
> And be prepared to handle z fighting issues.. using one of the
> standard ways.. also see
> vtkMapper::ResolveCoinicidentTopologyToPolygonOffset
>
> On Wed, Jan 27, 2010 at 10:27 AM, David Gobbi wrote:
>> Hi Rakesh,
>>
>> The method that you use to annotate the cell will depend on whether
>> you want to permanently color the cell, or whether you just want to
>> highlight it.
>>
>> If you just want to highlight the cell, then the best thing to do is
>> make a new polydata, set its color to black, and then add the picked
>> cell to the new polydata. Then add this new polydata to an actor and
>> add the new actor to the renderer so that it will render the black
>> cell over the original cell. Use the vtkGenericCell as an
>> intermediate for getting the cell from the original polydata and
>> adding it to the new polydata.
>>
>> By doing things this way, you would leave the original polydata
>> unchanged, and create a new "annotation" actor that has your picked< br>>
>> cells. I'm not sure if this is would meet your needs, but it would be
>> a straightforward way of visualizing the cell pick.
>>
>> David
>>
>>
>> On Wed, Jan 27, 2010 at 7:01 AM, Rakesh Patil wrote:
>>> Hello,
>>>
>>> I want to implement picking. With the help of an example,
>>> annotatePick.tcl,
>>> i'm able pick a cell, but annotation is not possible..
>>>
>>> I am displaying a triangular mesh. And when the user clicks on any of the
>>> cell of the mesh, i need that particular cell to be filled with black.
>>> Only
>>> that particular cell has to be annotated as a filled black color.
>>>
>>> Is it possible..?? After picking i'm getting cellid, of the cell which is
>>> selected. How can i do the annotation..??
>>>
>>> Thanks in advance
>>>
>>> Regards
>>>
>>>
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