[vtk-developers] A weird 6.x specific bug with ModifiedEvents

[Bill Lorensen]

GetColor should return the value set by SetColor. If we need the
composite color then we should explicitly ask for it.

I'm not sure why this change was made. Kyle made it.

Bill


On Mon, Apr 14, 2014 at 12:52 PM, Bill Lorensen <bill.lorensen at gmail.com> wrote:
> So here is the bug the sample code uncovers:
>
> SetColor
> 1) Sets the Color ivar to the requested color
> 2) SetColor calls SetAmbientColor which triggers the Modified event
>     The Modified event call GetColor which calls ComputeCompositeColor
> and computes a composite color
>     The composite color is not correct
> 3) Color continues to get corrupted with SetDiffuseColor and SetSpecularColor.
>
>
>
> On Mon, Apr 14, 2014 at 12:40 PM, Bill Lorensen <bill.lorensen at gmail.com> wrote:
>> I do not think that GetColor should change the value of Color. If we
>> need the composite color, we could have a method GetCompositeColor().
>> No SetCompositeColor.
>>
>> Bill
>>
>>
>> On Mon, Apr 14, 2014 at 12:24 PM, Bill Lorensen <bill.lorensen at gmail.com> wrote:
>>> Really bad stuff. ComputeCompositeColor "sets" this->Color directly.
>>> ComputeCompositeColor was added about a year ago...
>>>
>>>
>>>
>>> On Mon, Apr 14, 2014 at 12:18 PM, Bill Lorensen <bill.lorensen at gmail.com> wrote:
>>>> This is indeed weird.
>>>>
>>>> GetColor does not return the value set by SetColor. It calls
>>>> ComputeCompositeColor.
>>>>
>>>> Also, SetColor calls SetAmbientColor, SetDiffuseColor and
>>>> SetSpecularColor. Each should cause a Modified event. In fact if you
>>>> remove the o.GetColor() call in the Modified callback, you will see
>>>> three modified events and each call will change one more of the color
>>>> s (ambeint, diffuse, specular).
>>>>
>>>>
>>>> Very strange.
>>>>
>>>> Bill
>>>>
>>>>
>>>> On Mon, Apr 14, 2014 at 11:35 AM, Prabhu Ramachandran
>>>> <prabhu at aero.iitb.ac.in> wrote:
>>>>> Hi everyone,
>>>>>
>>>>> I just discovered a weird bug with VTK 6.1 and 6.0 that doesn't happen with
>>>>> VTK 5.x.  Here is a tiny Python script:
>>>>>
>>>>> ##################################################
>>>>> import vtk
>>>>> def f(o, e):
>>>>>     print e, o.GetAmbientColor(), o.GetColor(),
>>>>>     print o.GetDiffuseColor(), o.GetSpecularColor()
>>>>>
>>>>> p = vtk.vtkProperty()
>>>>> p.AddObserver('ModifiedEvent', f)
>>>>> p.SetColor(0,0,0)
>>>>> print p.GetColor()
>>>>> ##################################################
>>>>>
>>>>> If you comment out the AddObserver line, everything works correctly but with
>>>>> it, you can never set the color of the property!  This doesn't seem to be
>>>>> specific to Python and happens with a small C++ example as well.
>>>>>
>>>>> Thoughts?
>>>>>
>>>>> cheers,
>>>>> Prabhu
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>>>>
>>>>
>>>> --
>>>> Unpaid intern in BillsBasement at noware dot com
>>>
>>>
>>>
>>> --
>>> Unpaid intern in BillsBasement at noware dot com
>>
>>
>>
>> --
>> Unpaid intern in BillsBasement at noware dot com
>
>
>
> --
> Unpaid intern in BillsBasement at noware dot com



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