How do I get material blend nodes to use 'overlay' for normal maps?

Rekov

I've been attempting to follow some of the official tutorials for Substance Designer, and I am running into a problem with the material blend node. Whenever the tutorial uses it, it seems to overlay the normal maps of the two materials. When I use it however, it seems to just copy one over the other, and half the data is lost. I don't even have the option to set a blending mode. Apparently this might have been changed in the newer versions of Designer?



This is the tutorial I am following at the appropriate moment: https://youtu.be/b2LKMffeiWE?t=1m25s

When I follow those exact steps, all of the information for the shape of the nails is lost, because the metal base material's flat normals just overwrite it. https://giant.gfycat.com/MilkyPerfectKinglet.webm

Now, I can already think of a few ways to work around this. I could blend the normal maps independently of the material blend node, for example. But it seems like the must be a more efficient way to do this. Any ideas?

m4dcow

As far as I can tell he is just blending in flat normal data ie: no overlay sort of blending (I see at 8:44). His mask doesn't end up being super hard so there is a bit of a blend on the edges and it looks like he did some stuff in the graph to have a depression in the area around the nails, which might be mistaken for some sort of nail normal detail.

If your nails have detail and you would like to blend that in but not stray too far from the tutorial, just go into the more expanded material mode, and pipe your normal into the appropriate slot.

Rekov

Earlier in the tutorial we create the normal/height data for the nails (both a depression around the nails and raised nail-heads), and it's part of the wood plank base material that we're blending into the background. So is he just messing up in this part of the tutorial by totally overwriting that data?

Alexastor

Rekov said:

Earlier in the tutorial we create the normal/height data for the nails (both a depression around the nails and raised nail-heads), and it's part of the wood plank base material that we're blending into the background. So is he just messing up in this part of the tutorial by totally overwriting that data?

Hey Rekov, I found a solution for you as I ran into the same problem watching that tutorial.

The regular Material Blend only supports "Normal Blend", but what we need in cases of rust is actually "Normal Combine".

I simply made a copy of the "Material Blend" graph/node, named it "Material Blend Normal Combine" and inserted a "Normal Combine" node.

It now works like we want it to:

As a next step, one could probably just add a switch, so the user could switch between blend and combine - it'd actually be great if the default graph that ships with Substance could do this.