BabylonJS/Babylon.js · error

TrailMesh: generator not found with ID

Error message

TrailMesh: generator not found with ID 

What it means

TrailMesh.Parse is the deserialization entry point used when a saved scene containing a TrailMesh is loaded. A TrailMesh must be bound to the generator (mesh or TransformNode) it trails; serialization stores only the generator's ID. If neither a mesh nor a transform node with that ID exists in the scene at parse time, the TrailMesh cannot be constructed and this error is thrown.

Source

Thrown at packages/dev/core/src/Meshes/trailMesh.pure.ts:295

     * @param serializationObject object to write serialization to
     */
    public override serialize(serializationObject: any): void {
        super.serialize(serializationObject);

        serializationObject.generatorId = this._generator.id;
    }

    /**
     * Parses a serialized trail mesh
     * @param parsedMesh the serialized mesh
     * @param scene the scene to create the trail mesh in
     * @returns the created trail mesh
     */
    public static override Parse(parsedMesh: any, scene: Scene): TrailMesh {
        const generator = scene.getLastMeshById(parsedMesh.generatorId) ?? scene.getLastTransformNodeById(parsedMesh.generatorId);

        if (!generator) {
            throw new Error("TrailMesh: generator not found with ID " + parsedMesh.generatorId);
        }

        const options = {
            diameter: parsedMesh.diameter ?? parsedMesh._diameter,
            length: parsedMesh._length,
            segments: parsedMesh._segments,
            sections: parsedMesh._sectionPolygonPointsCount,
            doNotTaper: parsedMesh._doNotTaper,
            autoStart: parsedMesh._autoStart,
        };
        return new TrailMesh(parsedMesh.name, generator, scene, options);
    }
}

let _Registered = false;
/**
 * Register side effects for trailMesh.
 * Safe to call multiple times; only the first call has an effect.

View on GitHub (pinned to 0592b347b8)

Solutions

1. Keep the generator mesh/TransformNode in the same scene file with the exact generatorId the TrailMesh references.
2. Restore the missing generator (re-add it to the .babylon file or recreate it with the matching id) and reload.
3. If the generator is intentionally absent, remove the TrailMesh entry from the serialized scene data.
4. Log parsedMesh.generatorId and compare against scene.meshes / scene.transformNodes ids to find the missing or mismatched reference.
5. Use unique, stable ids for meshes that other objects reference when saving scenes.

Example fix

// before (.babylon JSON)
{ "name": "trail", "type": "TrailMesh", "generatorId": "oldMeshId" } // no mesh with oldMeshId
// after: keep the generator in the scene file and fix the id
{ "name": "generator", "id": "genMesh", ... }
{ "name": "trail", "type": "TrailMesh", "generatorId": "genMesh" }

function trailMeshGeneratorPresent(scene, generatorId) {
  return scene.getLastMeshById(generatorId) != null || scene.getLastTransformNodeById(generatorId) != null;
}
// before/while loading the serialized scene, or before parse:
if (!trailMeshGeneratorPresent(scene, parsedMesh.generatorId)) {
  console.warn('TrailMesh generator missing:', parsedMesh.generatorId);
}

function hasGenerator(scene, generatorId) {
  return scene.getLastMeshById(generatorId) instanceof BABYLON.AbstractMesh
      || scene.getLastTransformNodeById(generatorId) instanceof BABYLON.TransformNode;
}

try {
  const trail = TrailMesh.Parse(parsedMesh, scene);
} catch (e) {
  if (String(e.message).startsWith('TrailMesh: generator not found')) {
    console.warn('Skipping TrailMesh whose generator is missing:', parsedMesh.generatorId);
    // recreate generator or skip loading the trail mesh
  } else { throw e; }
}

When it happens

Trigger: SceneLoader/Scene.Parse loading a scene whose serialized TrailMesh has a generatorId matching no mesh or transform node in the scene — e.g. the generator mesh was removed from the saved file, its id changed, or parsing order/deferred loading meant the generator did not exist yet.

Common situations: Hand-editing a .babylon file and deleting or re-id'ing the generator mesh; stripping meshes from a saved scene to shrink it while leaving the TrailMesh entry behind; loading a partial scene file into a scene without the generator; saving one scene and loading the TrailMesh into a different scene.

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AI-assisted analysis of BabylonJS/Babylon.js@0592b347b8 (2026-08-30). Data as JSON: /api/errors/0dada5fa746d38be. Report an issue: GitHub.