Limitation of true displacement in Blender

I am pretty sure this counts as a limitation and not as a bug of true displacement in Blender, but if normals are not smoothed in some way the displacements may cause gaps in the mesh:


The image shows two identical meshes (created with Shift D) with the same material applied. This material uses true displacement and both objects have a simple adaptive subdivision modifier.
The one on the left has all faces flat shaded while the one on the right has all faces smooth.
The gaps are obvious.

Apparently this is caused by having normals across the the edges of adjacent faces that point in different directions as displacement is along the normals. With smooth faces the calculated normals blend into each other, which will cause displacement near an edge to go in the same direction.

The same smoothing effect can be achieved by changing the adaptive subdivision modifier from simple to catmull-clark.  (catmull-clark effectively interpolates the normals before subdividing)

Again, I don't think this counts as a bug, but it is good to know if just to prevent some head scratching.

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