Hi,
Yes you're right regarding the "Generated Outputs" channels, that's where you can modify the settings regarding channels mapping.
At the bottom of the Substance properties, you can choose what you want to use in the alpha channel of the corresponding output. By default, you get the source alpha (=the default alpha of the corresponding output), but you can use other channels as alpha.
In this case, if you use the "Source" alpha, you'll get something white. You have the possibility to change the gloss value uniformly to have something which can fit with your material type.
Unfortunately, there is no "Glossiness" map generated by the current version of the Bitmap2Material.
An important point: create a new Unity material instead of using the material directly assigned in the Substance to avoid some issues. Some outputs assignation can behave incorrectly.
A workaround (not perfect, but which can help if you need something really specific for the gloss map, and don't really care about the specular sharpness) is to use the height as a specular (you can adjust it with the "height" related parameters to have something more correct) and your specular as gloss. Here are the main steps:
- In the Substance properties, put the "Specular" in the alpha of the "Height" output (as in the picture below)
- In your skyshop material, drag n'drop your height in the "Specular/gloss" slot.
- You can now adjust the gloss with the "Specular" parameters in the Substance. And your Specular with the "Height" parameters.
You can also adjust them using the global parameters of the shader (Specular and Gloss values).
Hope it will help you even if it's not perfect.