I've noticed that when using the Shingle tool on roofs with concave slopes, like screengrab, the slope component of a roof does not show; it only works on convex roofs.

Would it be possible to allow the slope component to also work on concave slope joins please? Or have I missed something?

In my case, Classical Roman buildings would frequently have arcade roofs like this, and would have imbrices placed along the join.

Hello Julian.

Shingle tool was originally created for the company which is specializing in making visualizations for roof tile manufacturers.
So every parameter and shingle type in the tool is based on real sets of roof tiles from the real manufacturers.
There was no need for this type of shingle, they not requested it.

But there is "Inner Offset" parameter in the tool which you can adjust, and leave a space for placing concave slope shingles manually.

I hope this helps.

Thanks Viktor. What I wanted specifically applies to Roman buildings, specifically the conical roofs of an apsidal end. I suspect they used regular tegulae and imbrices to tile these roofs, not a special curved tile. Oddly enough, the Vienna.pst seems to work on a cancave surface. whereas Roman.pst does not. And I've not been able to get my own shingle elements to work yet either. They work great on a flat roof of course, but not curved. But I'll keep trying, and thanks for the help.