Trouble getting the hang of subsurface in SP8 for UE4

[morningstar666]

It's me again!

So far we've been enjoying the new version immensely. The new options and the optimized workflow are a treat!

However, I've been having some issues with some of the available maps for the materials, namely the subsurface/subsurface% ones, especially when making leaf clusters for my tree.

They do work in Speedtree, even if I ramp up the intensity of the light.



But when imported to Unreal, making sure to select the "include subsurface" option, the subsurface doesn't work:



When I check the material, there is no subsurface map, and the material shading model is set to default lit.

Do I have to manually change the shading model and import the subsurface map? Or am I doing something wrong from the speedtree step?

Thanks in advance.

[Greg Croft]

Hello,

Subsurface is only added to the two-sided materials. Are you sure you're checking the leaf material? It certainly looks like you have subsurface on the leaves in your pic...

[morningstar666]

In speedtree, when making the mesh cutout for my leaf cluster material I checked the two-sided option-- do I have to do something else to make the material two-sided or is that it?

And I checked the leaf-mat material that was automatically generated when importing the .st file-- everything else was the billboards and trunk materials.

What I'm confused about is the color of the subsurface itself-- it's green (the way I set it up in Speedtree), while in unreal is very desaturated, almost white. Is this normal?

[Greg Croft]

Ah, you made the mesh itself two-sided. You need to make the materials two-sided instead, in the material asset bar.

The subsurface texture exported to UE4 is a combination of color and amount. The final effect depends on the light color, and how bright it is, etc.

[morningstar666]

Thanks for the tip. Enabling the two-sided option in the leaf material does help out a lot!

Now I have another question-- do you also have to enable the two-sided option in the material you use in the tree itself? Or do you only have to do it when setting up the leaves in the cluster? Because if I make the cluster material two-sided, the wind animation for my texture breaks entirely. As in, rather than moving in a swooping motion, the cluster texture constantly switches back and forth between its two sides and it's rather jarring. :/

[Greg Croft]

Hello,

Two-sided doesn't change the wind motion, but it sounds like the two sides of your mesh are intersecting during wind. When you want to use a two-sided material, you should not have a two-sided mesh. So make your mesh again without doing two sided, and there should be no more intersection in wind.