Hi Ben,

Thanks for helping out with this. Thorsten also posted his question in the NUKE
Dev forum
<http://community.thefoundry.co.uk/discussion/topic.aspx?f=191&t=121325> on
our community pages; would you mind if I copied your response there, so
that others who find the thread will be able to see the solution?

Regards,
Lucy

On Tue, Mar 29, 2016 at 2:07 PM, Ben Dickson <[email protected]> wrote:

> Probably easier using the knob_changed on the XY position knob as Lucy
> describes, but.. you could maybe do something with the
> NDK/examples/Handle.cpp "Glue_knob":
>
> In your handle(...) method, check if a "pick" boolean-knob next to your
> Axis-knob is enabled and, if so, sample the input to get the pixel value
> from whatever channel you wish. Would function quite similarly, except for
> the pretty colour-swatch icon, and some probably a lot of subtly like the
> red box showing the selected area etc..
>
> A quickly-shoved-together untested example:
>
> bool MyPlugin::handle(ViewerContext* ctx, int index)
> {
>   switch (ctx->event()) { // DRAG/PUSH etc
>     case RELEASE:
>       if(ctx->state(SHIFT) && index == 0){
>         Pixel p(Mask_RGB);
>         input0().sample(
>           /* x */ ctx->x(),
>           /* y */ ctx->y(),
>           /* w, h */ 1, 1,
>           /* pixel */ p);
>         knob("value")->set_value(p[Chan_Red], 0);
>         knob("value")->set_value(p[Chan_Green], 1);
>         knob("value")->set_value(p[Chan_Blue], 2);
>       }
>       break;
>
>     default:
>       break;
>   }
>
>   return true;
> }
>
>
>
> On 29/03/16 22:04, Lucy Wilkes wrote:
>
>> Hi Thorsten,
>>
>> You can certainly do the sampling you describe, though you won't get a
>> "pick" control with other knob types. See for example the ZDefocus
>> node's "focal point" XY_Knob, which picks from the depth channel when
>> the point is moved in the UI (or changed manually). Would this type of
>> sampling be sufficient for what you require? Or did you specifically
>> want a pick mode?
>>
>> Thanks,
>> Lucy
>>
>> On Tue, Mar 29, 2016 at 12:21 PM, Thorsten Kaufmann
>> <[email protected]
>> <mailto:[email protected]>> wrote:
>>
>>     Hey there,____
>>
>>     __ __
>>
>>     I want to give users the possibility to pick AOV values (namely Vec3
>>     positions in this case). So the only way to allow for picking would
>>     be using a Color_Knob. Ideally i would prefer to store in an
>>     Axis_Knob or similar. But i want to be able to hit "pick" and have
>>     the user pick a value in the viewer.____
>>
>>     __ __
>>
>>     Is that possible using the current set of built-in knobs? And if not
>>     (that is if i have to resort to just using the Color_Knob) is there
>>     a way to force the picker to work on a specific ChannelSet? Ideally
>>     the user would look at RGB to see where he wants to pick and sample
>>     from the world position channels.____
>>
>>     Would that be possible?____
>>
>>     __ __
>>
>>     Cheers and thanks,____
>>
>>     Thorsten____
>>
>>     ---
>>     Thorsten Kaufmann
>>     Production Pipeline Architect
>>
>>     Mackevision Medien Design GmbH
>>     Forststraße 7
>>     70174 Stuttgart
>>
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>>     M +49 151 19 55 55 02 <tel:%2B49%20151%2019%2055%2055%2002>
>>
>>     [email protected]
>>     <mailto:[email protected]>
>>     www.mackevision.com <http://www.mackevision.com>
>>
>>     Geschäftsführer: Armin Pohl, Joachim Lincke, Jens Pohl
>>     HRB 243735 Amtsgericht Stuttgart
>>
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>>     *VFX:* Game of Thrones, Season 5 – VFX making of reel
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>>     *TWITTER | ADOBE BEHANCE:* Follow us on Twitter
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>>     <https://www.behance.net/mackevision>.
>>
>>
>>     _______________________________________________
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>>
>>
>>
>>
>> --
>> Lucy Wilkes
>> |
>> |
>> Senior Software Engineer
>> The Foundry
>> 5 Golden Square, London, W1F 9HT
>> Tel: +44 (0)20 7479 4350
>> Web: www.thefoundry.co.uk <http://www.thefoundry.co.uk/>
>> Email: [email protected]
>>
>>
>> The Foundry Visionmongers Ltd.
>> Registered in England and Wales No: 4642027
>>
>>
>>
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>>
> --
> ben dickson
> 2D TD | [email protected]
> rising sun pictures | www.rsp.com.au
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>



-- 
Lucy Wilkes

Senior Software Engineer
The Foundry
5 Golden Square, London, W1F 9HT
Tel: +44 (0)20 7479 4350
Web: www.thefoundry.co.uk
Email: [email protected]


The Foundry Visionmongers Ltd.
Registered in England and Wales No: 4642027
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