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OpenGL Garbage when clearing/rendering to texture

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I'm implementing transparency using depth peeling. I have an implementation that works. But things start to fail when I resize my window. When I glClear my resized blended color texture (the one that stores the result of blending each consecutive peeled layer over the previous ones) before the first pass, It should become all black (alpha being 1.0). Instead it looks like this:

[img]http://i40.tinypic.com/23prh4.png[/img]

(the white/grey pattern was added by the tool I use to view the texture). Obviously this does not result in a correct final result :-)

[img]http://i44.tinypic.com/kbw19s.png[/img]

I check for OpenGL errors after each single gl function call, but no errors are generated. My fbo's are complete, and when I use gDEBugger I can see that all textures/render targets have the same size. I have been looking into textures being attached to an fbo and a texture unit at the same time. I've been playing with the wrapping and mipmap settings to fix things. But I can't find the problem. Can anyone give me hints here? I would be very grateful!

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