Alpha bug?

Hey !

I am losing my hair on this problem - and it is so simple !

I have a simple renderer showing a graphic with alpha channel.
Then I pipe this into another renderer. No effects are appied, it just flows as texture into another renderer.

And all of a sudden the alpha values are incorrect. We lose data somehow. It is not 1:1 the same, but should be, right?

I attach the patch here in case you guys have more luck and tell me what is going on here. An alpha bug? Or am I buggy? =) (3.1 kB)

welcome to the high arts of blending :)
what happens in the first renderer is an alpha blending with the background, which is black in your case. so the color channels get mixed with black where the alpha channel is less than 1.
in the second renderer you are doing the same thing, so it gets even darker.

you have two options depending on how and when you want to modify the color channels, either disable alpha blending in the first renderer, or disable it in the second renderer:

Brush.v4p (8.5 kB)

and some theory transparency