hey, so im sening spout from unreal, it has an empty alpha channel , but touch is rendering the alpha channel over the rgb…
it is “fixed” when i use a black constant and set it atop, but it seems strange that this would be happneing.
top left is the internal spout receiver, center is unreal, and right is TD.
the alpha channel in unreal is empty, (its sending but its empty)
wonernig whats going on here, thanks!!!
If the alpha channel is all 0s, then that’s what’ll be shown in our viewers. You can use a Reorder TOP to replace the alpha with 1s, if that is what you want instead.
but it seems like a weird thing, that’s its showing the alpha above the rgb, no?
I’m not sure I follow. What does the TOP To CHOP say the values are?
the alpha channel is 0, so shouldn’t there be no alpha? and even if so, why am i seeing through opaque objects?
as you can see from the sending (unreal) and the ground truth (spout) there is no alpha visible, i would excpet the same from the spoutin top…
Alpha of 0 means transparent. So this image is entirely transparent as far as the alpha is concerned. However with compositing, your RGB should never be higher than your alpha, so the data in this image won’t work correctly for compositing operations, such as Over ontop of the checkboard background, as the TOP viewer is trying to do. Things will look wrong.
Those other viewers just arn’t showing you the alpha one way or the other. They are just showing the RGB. You can turn off the Over operation in the Preferences->TOPs page, so show black as the background as well (instead of the Over checkerboard), like those other viewers are doing.
ok i understand. its strange though because those viewers can show alpha, if the alpha is sending something.
Meaning if there is an alpha channel that isnt just 0 there will be a “checkboard” where there is alpha…
i geuss im excpecting a 0 alpha channel, to not be viewable as its essentially useless/not being used.
but adding a reorder top fixes this.
thanks malcolm
0 alpha doesn’t mean useless/not being used. It means the pixel is transparent. I’m not sure why they are written 0 to the alpha channel of that texture, but that is what is coming over. They aren’t ‘not sending alpha’. They are sending RGBA and the alpha channel is 0.
