FMeshNormals::QuickComputeVertexNormals is resulting in visible seams between procedurally generated terrain 'chunks'

[russwb]

I am building a procedural terrain using UDynamicMeshComponent. Each ‘chunk’ that is calculated is joined using FDynamicMeshEditor->AppendMesh. Finally, once all calculation/merging is complete, FMeshNormals::QuickComputeVertexNormals is used to calculate the vertices for the final mesh.

Here is how the issue looks using the world normal visualization:

That is zoomed in on the border between two chunks (which have since been joined into one mesh). The normal difference results in a poor look on these edges, and seams.

[russwb]

The problem seems to be that in FDynamicMeshEditor->AppendMesh, identical vertices are duplicated instead of shared. So when the final normals are calculated, the weighting is incorrect.

This should be pretty easy to fix manually by just checking for identical vertices, but I’m also certain there must be an automatic flag or way to do so as well within the engine?