Merging/blending alpha channels for fluid emitter density emission map

[hotbox]

Hi,

I have a couple of 2D textures (one animated), I need to combine the alpha channels and send the result to the density emission map of a fluid emitter.

I've tried various methods including layered texture and mib_color_mix but can't get the emitter to use the merged/blended alpha (can you actually take the resultant alpha out of mib_color_mix?).

I'm thinking there may be a simple way to do this - perhaps just with the textures? I'm going to have another look today but any advice would be much appreciated!

Many thanks.

[chartt]

I have found that alpha channels can be "rebuilt" using ramps.

Combine your textures anyway you want to and then pipe the output into a ramp.

outcolor -> 1 color position on your ramp.
outAlpha -> inalpha of your ramp.

If you want to use your outcolor as your alpha, convert to 1 channel using a luminance node and pipe that into your ramp.

Use the ramp as the emitter texture.