RGB merge for export help

Harbinger

Hi Substance experts,

I'm trying to pack separate greyscale channels into a single RGB or RGBA texture for export and use in UE4, but I've run into a little problem.



I won't always have an emissive input to pack into the alpha channel depending on which asset is pumped through. Using the default RGBA Merge node, it won't compute an output unless all 4 channels have inputs.

My first thought is to create my own RGBA merge node that has some kind of logic to detect whether an alpha is plugged in or not. Would that be possible?

I know this might seem trivial because I could just plug in a dummy value into the Alpha slot and then strip it back out later in Photoshop. However, I'm interested using Substance integrated into larger pipelines where I want to avoid as much of the manual steps as possible.

Jerc

Actually you have an output right there, it's just transparent because the default alpha, like all greyscale input in SD, is black if nothing is plugged in it. You could modify the RGBA Merge node to add a switch for the alpha or make a second node that would be a simple RGB merge without the alpha channel.

Harbinger

Hi Jerc,

OK I'm a step closer. What you said makes sense, so thanks! Right now I have my maps exporting properly, but they all all come with alpha channels by default when I export with the "Export outputs as bitmaps" option on the substance graph. Is there a way to make my graph or outputs smarter so they only export 3 channel images if there is no alpha channel information? Your suggestion with modifying the RGBA Merge node with a switch would still pump data into a regular output node, right? So I'd still see the alpha channel in the final image output?

Thanks for the help!

Jerc

Unfortunately there is currently no way to export bitmaps without an alpha channel unless you use a format that doesn't support it, like bmp. It's on our short term task list.

Harbinger

Great, thanks again!