Creating blur with an alpha channel, incorrect inclusion of black

Posted by edA-qa mort-ora-y on Game Development See other posts from Game Development or by edA-qa mort-ora-y
Published on 2014-05-28T07:57:03Z Indexed on 2014/05/28 16:01 UTC
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algorithm

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glsl

I'm trying to do a blur on a texture with an alpha channel. Using a typical approach (two-pass, gaussian weighting) I end up with a very dark blur. The reason is because the blurring does not properly account for the alpha channel. It happily blurs in the invisible part of the image, whcih happens to be black, and thus results in a very dark blur.

Is there a technique to blur that properly accounts for the alpha channel?

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