[osg-users] Setting alpha channel in Frag Shader does not work.

J.P. Delport jpdelport at csir.co.za
Wed Mar 18 13:13:01 PDT 2009


the file

J.P. Delport wrote:
> Hi,
> 
> I haven't read your code, but I'm sure alpha channel works just fine.
> 
> Attached is a modified osgmultiplerendertargets example. Run it with
> osgmultiplerendertargets --image
> which should print a=128
> 
> or with
> osgmultiplerendertargets --hdr --image
> which should print a=-1.1
> 
> You can adjust the values in gl_FragData[0].
> 
> rgds
> jp
> 
> 
> Steven Powers wrote:
>> danielh wrote:
>>> Try attaching a texture to the COLOR_BUFFER0 instead of an image 
>>> directly.
>>> That's what worked for me.
>>
>>
>>
>> Thats what this code is doing. I've written to COLOR_BUFFER0 and 
>> whenever I change the shader alpha value to something other than 1 all 
>> color values come back incorrect.
>>
>> This will be read correctly:
>>  
>> Code:
>> gl_FragColor = vec4(1,2,3,4, 1);
>>
>>
>>
>> But this will be read incorrectly:
>>
>> Code:
>> gl_FragColor = vec4(1,2,3,4, .5);
>>
>>
>>
>> ------------------
>> Read this topic online here:
>> http://forum.openscenegraph.org/viewtopic.php?p=8707#8707
>>
>>
>>
>>
>>
>> _______________________________________________
>> osg-users mailing list
>> osg-users at lists.openscenegraph.org
>> http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
>>
> 

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