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I know these scripts work because they've worked wonders on the Crumbling Crypt set I started building in 2021. Hopefully I can simplify them to work for you too.

Additional Considerations Not Related to the Mesh

Light Node ShadowRadius Value

While everything so far presented here is mesh relative, there is one other issue that does come up sometimes, and that's lightsource related.

Light sources have two properties, Radius and Shadow Radius. By default, shadow radius equals light radius, therefore a torch with max radius 20m will also only cast a shadow to 20m, and a torch of only 2.5m radius also casts only a 2.5m shadow.

In most cases, people make their torch radius with multiplier x1, meaning the intensity is also set by the radius. A longer radius is effectively a stronger light. So a short radius light really wouldn't cast a long shadow anyway, right?

But let's investigate a deep pit in a DARK region where you're using a torch. If the torch max radius is 20m and your pit is 40m, then the bottom of your pit will be brighter than the shadowed section, which will look very odd.

You can fix that issue by modifying your torch lights. OC torches, rings and light effects are going through the file fx_light_clr.mdl. In that model you will see no shadow radius values for any of the lights. If you want your shadows in your world to reach the furthest extents, then you need a ShadowRadius value equal to the extent you want reached.

Take note that a longer shadow requires more drawing time. So setting your values to crazy high numbers will also make more work for the shaders. Likewise setting shadow radius lower will improve draw speed.

Tile Bounding Box

Another pit-related example can be used to examine the next case scenario. Imagine you have a deep pit in a well lit area, and you want the mesh along the pit to shade the pit all the way down.

To get this to occur, you need to have a correct pit-related bounding box. Light will not be drawn below the shadow-casting tile's lower bounds. So for example adjacent to your pit, you may have a flat floor tile with a lower bounds of around 0 elevation. This tile will not shadow very deeply into the pit next door.

To fix this issue, you can simply put a tiny mesh node way down below the tile origin. Place the mesh at the depth of your deepest pit, minus the height of your area height transition. That should work for almost all cases.