[vtkusers] vtk.js: display particular cells with alpha/transparency/opacity

[Sebastien Jourdain]

Thanks for doing this. Indeed I see the issue and reported a bug here:

https://github.com/Kitware/vtk-js/issues/982

On Fri, Dec 14, 2018 at 3:22 AM Raimonds Vilums <raimonds at cenos-platform.com>
wrote:

> https://codepen.io/raimonds-vilums/pen/OrMrEz
>
> After load, you can see colored cells without transparency (3-component
> array).
>
> For loading 4-component array, change array name on line 187
> from mapper.setColorByArrayName('*rgbData*');
> to mapper.setColorByArrayName('*rgbaData*');
> which does not work.
>
> Raimonds
>
>
> On Thu, Dec 13, 2018 at 6:59 PM Sebastien Jourdain <
> sebastien.jourdain at kitware.com> wrote:
>
>> Can you do a codepen and share it so I can see what you are doing exactly?
>>
>> On Thu, Dec 13, 2018 at 9:26 AM Raimonds Vilums <
>> raimonds at cenos-platform.com> wrote:
>>
>>> I tried and got
>>>
>>> index.js:441 Uncaught (in promise) TypeError: Cannot add property 3,
>>> object is not extensible
>>>     at Object.publicAPI.rGBAToRGBA (index.js:441)
>>>     at Object.publicAPI.convertToRGBA (index.js:487)
>>>     at Object.publicAPI.mapScalars (index.js:238)
>>>     at Object.publicAPI.mapScalars (index.js:272)
>>>
>>>
>>>
>>> On Thu, Dec 13, 2018 at 6:10 PM Sebastien Jourdain <
>>> sebastien.jourdain at kitware.com> wrote:
>>>
>>>> You should be able to have an array with 4 components (RGBA)
>>>>
>>>> On Thu, Dec 13, 2018 at 9:01 AM Raimonds Vilums <
>>>> raimonds at cenos-platform.com> wrote:
>>>>
>>>>> Hi,
>>>>>
>>>>> Is it possible to display cells with custom opacity for each cell?
>>>>>
>>>>> Till now, I managed
>>>>> 1) set opacity to the actor (e.g., actor.getProperty().setOpacity(0.5)
>>>>> )
>>>>> 2) color cells with solid colors, e.g:
>>>>>
>>>>>
>>>>>    - vtk file contains CELL_DATA array of floats with 3 components
>>>>>    for every color
>>>>>    -
>>>>>
>>>>>    mapper.setColorModeToDirectScalars();
>>>>>
>>>>>    -
>>>>>
>>>>>    mapper.setScalarModeToUseCellFieldData();
>>>>>
>>>>>    -
>>>>>
>>>>>    mapper.setColorByArrayName('my_cell_data');
>>>>>
>>>>>
>>>>> But I could not find a way to set alpha/opacity/transparency for
>>>>> particular cells.
>>>>> Is it possible?
>>>>>
>>>>> Regards,
>>>>> Raimonds
>>>>>
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