WebGL alpha blending is incorrect (premultiplied alpha issue)

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We're still not calculating alpha blending correctly. In the attached image: 
left is WebGL, right is Canvas. Notice the dark line when blending from 
transparent to white.

Due to stability issues, specifying premultiplied alpha at the webgl attribute 
level isn't an option. I think the best route is to do this ourselves in code 
(e.g., gl.blendFunc(ONE, INVERSE_ALPHA) and premultiply the color channels when 
loading the image).

Original issue reported on code.google.com by pdr@google.com on 19 Jun 2011 at 8:37

Attachments:

• premultiplyissue.png