# BABYLON.Mesh.MergeMeshes fails on merging \_\_root\_\_ mesh generated by GLB import

**URL:** <https://forum.babylonjs.com/t/babylon-mesh-mergemeshes-fails-on-merging-root-mesh-generated-by-glb-import/5574>\
**Category:** Bugs\
**Created:** [September 11, 2019, 7:16am UTC](https://forum.babylonjs.com/t/babylon-mesh-mergemeshes-fails-on-merging-root-mesh-generated-by-glb-import/5574 "2019-09-11T07:16:55Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![tlaukkan](https://sea2.discourse-cdn.com/flex024/user_avatar/forum.babylonjs.com/tlaukkan/32/8011_2.png) [@tlaukkan](https://forum.babylonjs.com/u/tlaukkan)\
**Post date:** [September 11, 2019, 7:16am UTC](https://forum.babylonjs.com/t/babylon-mesh-mergemeshes-fails-on-merging-root-mesh-generated-by-glb-import/5574/1 "2019-09-11T07:16:55Z")

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Hi

I imported glb mesh and tried to merge it. When enabling multiMultiMaterials error occurs at the following line when mergin **root** node generated by the GLB import. The root node is probably pure transformation node. Should this be reported or should I work around the issue?:

```
Error merging meshes: Error: Positions are required
    at VertexData../Meshes/mesh.vertexData.ts.VertexData._validate (babylon.js?7deb:97375)
    at VertexData../Meshes/mesh.vertexData.ts.VertexData.merge (babylon.js?7deb:97288)
    at Function../Meshes/mesh.ts.Mesh.MergeMeshes (babylon.js?7deb:96866)
    at eval (SpaceView.vue?d935:106)
    at successHandler (babylon.js?7deb:54206)
    at eval (babylon.js?7deb:54233)

```

Best regards,  
Tommi

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<div class="post-metadata">

**Author:** ![sebavan](https://sea2.discourse-cdn.com/flex024/user_avatar/forum.babylonjs.com/sebavan/32/57_2.png) [@sebavan](https://forum.babylonjs.com/u/sebavan)\
**Post date:** [September 11, 2019, 1:27pm UTC](https://forum.babylonjs.com/t/babylon-mesh-mergemeshes-fails-on-merging-root-mesh-generated-by-glb-import/5574/2 "2019-09-11T13:27:18Z")

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Ping @bghgary fyi.

Would be great if you could create on pg per issue as it could help narrowing it down.

About 1. I agree that it should merge meshes and not pure transforms like the root node.

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<div class="post-metadata">

**Author:** ![tlaukkan](https://sea2.discourse-cdn.com/flex024/user_avatar/forum.babylonjs.com/tlaukkan/32/8011_2.png) [@tlaukkan](https://forum.babylonjs.com/u/tlaukkan)\
**Post date:** [September 12, 2019, 4:31am UTC](https://forum.babylonjs.com/t/babylon-mesh-mergemeshes-fails-on-merging-root-mesh-generated-by-glb-import/5574/3 "2019-09-12T04:31:21Z")

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Hi

I separated the topics.

-Tommi

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<div class="post-metadata">

**Author:** ![bghgary](https://sea2.discourse-cdn.com/flex024/user_avatar/forum.babylonjs.com/bghgary/32/48532_2.png) [@bghgary](https://forum.babylonjs.com/u/bghgary)\
**Post date:** [September 12, 2019, 4:26pm UTC](https://forum.babylonjs.com/t/babylon-mesh-mergemeshes-fails-on-merging-root-mesh-generated-by-glb-import/5574/4 "2019-09-12T16:26:43Z")

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The ` __root__ ` is a mesh because of backward compatibility reasons. It should ideally be a `transformNode`, but doing that will break the API contract.