Wetness/Snow Issue In GIANTS Engine (FS25) For Complex Meshes

Skip forward to page 2 to read the conclusion.

This is a follow-up article about issues with the GIANTS Engine that was previously aired on AlfaMods.

There are two types of collision preset attributes for roads that can be applied to a collision mesh inside GIANTS Editor:

• ROAD
• ROAD_BRIDGE

The last one is faulty and not very accurate regarding the wetness applied by GIANTS Engine during rain.
When ROAD is the active collision preset, everything works as normal. But the visible raindrops in Farming Simulator will go through the mesh and be visible under the bridge.

When ROAD_BRIDGE is in use, the wetness will not follow the UVs of the mesh.

When the collision mesh is rendered as VISIBLE, we can see that it is embedded within and almost hidden in the bridge base mesh, as shown below.

But in Farming Simulator 25, the wetness later takes on a life of its own.

This will cause whiteness along the sides of the bridge and a sawtooth-like line between the wet and dry surfaces.
It simply means that the collision preset ROAD_BRIDGE is distorting the wetness itself.

The Solution

The solution to this problem is to add another collision mesh within the meshes and use it as a rain blocker to keep the ground and other map objects under the bridge dry. And yes, this mesh will use ROAD_BRIDGE for collision, while the main collision mesh will use ROAD.

Anyway, ROAD_BRIDGE affects wetness and is useless for slope-, elevated-, or curved-road bridges.

Alternative Solutions – Keeping Normal Map Color Space sRGB To Rotate UVs

So this one goes against the rules you’ll find almost at any web search for what color space normal maps should be set to in Blender. But you won’t see the wetness bug that shows up in Farming Simulator IF you are going to use color space Non-Color when unwrapping in Blender. The sRGB will reveal what actually happens in Blender, because Blender will rotate the UVs anyway, without your consent. This is a Blender problem, while the wetness issue in GIANTS Engine is largely related to the ROAD_BRIDGE collision mask.

So in the picture below, I am unwrapping these concrete barriers using the Angle-Based method. And with sRGB still enabled for the normal map, I can see when Blender rotates the UVs too much, giving the whiteness that makes GIANTS Engine think “oh…there’s a dry group of faces there…I’ll keep that spot dry”.

When I’m done with that (unwrapping 6,141 faces), I can put the colour space for the normal map back to Non-Colour.

If you want only dry surfaces on the mesh, or only at some locations on the mesh, well…here’s an alternative method for that:

If I take these selected faces into the UV Editing workspace and scale them to -1, they will not receive any wetness.

Same as with vehicle modding:

In Detail

I’m going to show you now what Blender 5.0.1 does on its own:

Those faces behind the orange selection mask are appearing white. When GIANTS Engine reads that information, it treats those faces as non-wet. And yes, Blender automatically rotates UVs, which have to be rotated manually to match the other faces. This is done by selecting Face > Face Data > Rotate UVs. And at times, you’ll have to rotate them several times to match the rotation of other faces.
We’ll have to do this because Blender isn’t simply that smart.

This will also affect the snow that a mesh object receives. If the wetness isn’t correctly displayed on the mesh, there won’t be any difference with snow either.

UV Rotation Using Mio3 UV (Faster UV Unwrapping)

Alternatively, there are free Blender add-ons, like this one. In this add-on, when viewed in the UV Editor sidebar panel, there’s a button labelled 180. This one will rotate the selected UV by 180 degrees, which corresponds to the darkest normal map variation, meaning full wetness.

What beginners making mod assets with Blender probably don’t know about, like myself, is that wetness for a mesh inside Farming Simulator 25 is mainly controlled by the normal and specular/gloss maps. And yes, the normal map controls most of the wetness, while the specular map is more like a wetness shininess controller.
So even if the GIANTS Engine Shaders include snow/wetness as adjustable attributes, and none of these is assigned to a mesh’s material, the normal map and specular/gloss map still control wetness, since wetness/snow is applied by the game engine when the weather conditions inside Farming Simulator 25 are snow or rain.

Viewport Shading Render Pass – Normal

This one will hopefully help you a lot with UV unwrapping when a material is using a normal map with tangent space. In fact, my highway intersection w/bridge is starting to look much better, with the light blue indigo colour, which is the correct UV rotation displayed on the mesh. The other colours are all the faulty ones affecting the wetness/snow mask, where some of these would be partly wet/snow, or no wetness/snow at all.

So, in Blender (for beginners), the material preview is often used during UV unwrapping. These spheres above the viewport are the viewport shading in use.
Next to those, there’s an arrow symbol pointing downwards. Click on that, and you’ll find the viewport shading panel.