[vtkusers] Rendering multiple actors with opacity (alpha)

[Michael Rice]

Oops, there was a typo in my post. The check is if opacity != 1.0  
(not 0 as in my original message).

On Aug 14, 2006, at 9:08 PM, Michael Rice wrote:

> This sounds like a problem we had. If you look in the  
> vtkOpenGLActor::Render() method, you see that the glDepthMask is  
> set to false if the opacity != 0 and the renderer is not picking.  
> Our simple hack was to comment out the if/else check that disables  
> the depth check. It doesn't produce the exact transparency we want,  
> but it is very close.
>
> As an experiment, you may want to try and modify vtkOpenGLActor.cxx  
> and see if that gets you closer to what you want.
>
> When I have some spare time, I'd like to craft a "real" solution  
> and submit it to Kitware for consideration.
>
> HTH.
> Michael
>
> On Aug 14, 2006, at 7:05 PM, Eugene Kim wrote:
>
>> Hi everyone,
>>
>> 	I've had an annoying little problem which should have an easy  
>> solution.  For any given actor that I add to an assembly,  
>> modifying it's alpha values in a lookup table makes its opaque to  
>> itself, but only somewhat so to other objects.  Depending on the  
>> order in which objects are added to the scene (via assembly), the  
>> first object will be opaque to itself but no other object, the  
>> second to only itself and the first, the 3rd to itself the second  
>> and the first, and so on.  It's very peculiar. Anyone know how to  
>> get this properly working?
>>
>> Thanks,
>> Eugene
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