This is attributed having the “Keep Quads” option enabled in a mesh’s import settings.

For input meshes used for the Spline Curve Mesher component this needs to be disabled

For the mesh generation, a 16-bit format is used to store the triangles. As opposed to 32-bit, this has wider platform compatibility (eg. Android) and benefits from higher performance.

If a mesh segment exceeds 65.535 triangles, then 32-bit is required. A conversion is done from 16- to 32-bit, but this incurs some precision loss, causing a few triangles to appear linked to the wrong vertices.

Ultimately the use of 16-bit is a design choice for performance and compatibility and accounts for the majority of use cases.

Solution: Use shorter segments to keep it under 65k triangles.

If the spline is shorter than your input mesh is, or the mesh is larger than a spline’s length: no geometry can and will be created.

Try making the spline longer.

Procedural meshes are always stored within the scene they are created in. Creating a prefab from a procedural mesh results in the data being lost. For prefabs, meshes need to be save to a file instead.

Solution: Use the “FBX Exporter” package and export the spline mesh to an FBX, then drag that mesh onto the prefab’s Mesh Filter instead. Delete the Spline Mesher component to avoid it being overwritten again!

Fallback solution: Enable the “On Start()” option on the “Rebuild triggers” dropdown, this will regenerate the mesh the moment the prefab loads.

While this is an unwanted effect, it is technically normal. The mesh gets repeated along the spline curve’s length. But in very tight corners many vertices can end up overlapping.

Mesh generation that collapses edges (of a cube) on the inside of corners is a very different concept to what this tool does.

This is perfectly normal and expected because the spline mesh and terrain have a wildly different topology.

Increase the “Height Offset” parameter to push the vertices up slightly.

For a Fill Mesher, it’s recommended to disable Shadow Casting (Renderer tab) so that the gap is not noticeable.

Preventing terrain from appearing through something like a road involves a modified shader (stencils or depth-offset). This is outside of the bounds of what this documentation covers.

Only crops up if the “Convex” option is enabled.

Very annoying, and unfortunately not something that can be resolved. The error in question is indeed “unspecified” and doesn’t provide any indication of what’s wrong with the mesh.

The error might occur some times, and when moving the spline just a tiny bit, it might not.

Solution: Ensure the output segments are not too short. This error is typically thrown when the individual colliders are short and simplistic. Using longer segments ensures this is not the case.

This is the physics system telling you that the mesh collider is broken. This happens if the generated mesh is invalid for some reason, usually hard to achieve on purpose.

For example, scaling the mesh to 0 or trimming it completely results in a mesh with 0 vertices, which is invalid.

While this is an unwanted effect, it is technically normal. The generated meshes are saved along with the scene and may end up being large.

Traditional meshes are saved to disk as a OBJ or FBX file. Having it “embedded” into the scene file does not directly have any adverse effects except for loading time efficiency.

Spline Mesher Pro already uses an optimized vertex layout, reducing file sizes by 50% compared to simpler tools.

For imported meshes (eg. FBX files), be sure to enable the “Read/Write” option in the import settings. This a requirement for meshes used in a build.

For C# generated meshes, mark the mesh as readable when creating it.

If you’re seeing this it’s unintentional. This means the mesh generation process did not complete entirely and was unable to clean up after itself.

If you go to ‘Preferences > Jobs > Leak Detection Level > Enabled With Stack Trace‘ the message will be thrown again the next domain reload (eg. altering a script).

After which the full stack trace will be logged in the console. If you are able to report this log message in full, I’ll be able to deduce how it occurred and work towards a fix or at least offer an explanation.

This is a limitation of Unity’s component system. You cannot perform any actions from an Awake or OnValidate function that will trigger a Spline Mesher component to rebuild.

If you’re seeing this, it’s a bug and completely unintentional.

Please report it (with the full error log) so it can be addressed!

This is a limitation of Unity’s component system. You cannot perform any actions from an Awake or OnValidate function that will trigger a Spline Mesher component to rebuild.

When using the Spline Mesher component at runtime, or in a build, the assigned input mesh must be readable.

For imported meshes (eg. FBX files), be sure to enable the “Read/Write” option in the import settings.

For C# generated meshes, mark the mesh as readable when creating it.

This generic error may be thrown when MeshLOD processes a spline mesh.

Neither the reason nor solution is known at the time. Ironically, the LODs are created just fine!

The version of the Burst package in your project was updated to a newer version. Restart the editor to complete the update.

There was a pop up dialog that instructed to do the same, it meant it 😉

Cause: You had Bakery installed at one point and removed it from your project.

In order to completely remove it, also remove the “BAKERY_INCLUDED” scripting define symbol from your project (Unity manual)

You’ve imported this asset into a Unity 2021 project anyway. This prompted the installation of the Collections v2.6.2 package, which is strictly incompatible with this version.

Delete the asset and downgrade the Collections package to a compatible version. You will need to upgrade to Unity 2022.3.23f1+ to use this asset (as noted on the asset store).