--- Operating System, Graphics card ---
OSX 10.6.8, MacBook Pro mid 2009
--- Blender version with error, and version that worked ---
Problems with 2.64 and 2.65a
--- Short description of error ---
The alpha channel does not seem to be affected by the mix node, independent of which blending mode is used (of course with alpha channel enabled). The alpha channel resulting from a mix node is identical to the upper input image's alpha channel.
--- Steps for others to reproduce the error (preferably based on attached .blend file) ---
Render the file and go to the compositor. I have added some viewer nodes to track the alpha.
Description
Description
Event Timeline
Comment Actions
I am a bit unsure that this is indeed a bug, however, in the manual it is stated that:
"Click the green Alpha button to make the mix node use the Alpha (transparency) values of the second (bottom) node. IF ENABLED, THE RESULTING IMAGE WILL HAVE AN ALPHA CHANNEL THAT REFLECTS BOTH IMAGES'S CHANNELS. Otherwise, (when not enabled, light green) the output image will mix the colors by considering what effect the Alpha channel has of the base (top input socket) image. The Alpha channel of the output image is not affected."
It seems like the current behavior of the Mid Node is not producing the correct alpha value for the resulting image.
Comment Actions
OK, I now managed to find a similar report earlier where it is explained that this is the normal behavior of the mix node.
I will instead suggest to clarify/correct the description in the manual wiki.
I apologize for the unnecessary post, next time I will triple check before posting.
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There's also code added yesterday to allow to define which of the 2 images you want to use alpha for the mix operation.
The wiki team has a hard time to keep up with all development... they always need more people :)