I’ve asked this question before and didn’t get a straight answer. I would like to be able to use a texture for a models specular. Apparently there isn’t a shader that has a separate texture slot for that. People were telling me to use the alpha channel.
How can you take a gray-scale texture and add it to an alpha of the color texture? I can’t figure out how to do that in Photoshop.
Also, what happens if you would like both an alpha as well as a specular? How do you get around that?
Other engines that I have tried had a material where the specular is a separate channel, in which you can drop in a texture.
But I’ve been painting directly on the alpha channel in Photoshop after creating it to get the effects I want. So I create the channel from a selection then paint on it using a shade of black/white/grey.
Don’t know how you get the result into a Specular Texture in Unity though.
Along the same lines as what RHD said, to add an alpha channel in Photoshop, switch to the Channels tab (where you should see four channels, RGB, Red, Green and Blue) and if you create a new Channel it’ll come up as Alpha 1
Copy and paste your grayscale image into that new layer, save it in a 32 bit format (like TGA) and you’ll have your alpha layer.