RFD 1031 details: the alpha wrap, permissive options, blocklist

What the alpha wrap does

The fork uses CGAL for alpha wrapping. Alpha wrapping turns a defective triangle soup into a watertight mesh. The Polygon Mesh Processing Library and Geogram do not implement it.

Permissive options

• fTetWild (wildmeshing/fTetWild, MPL-2.0) turns a triangle soup into a tetrahedral mesh with a watertight boundary. It is heavier and volumetric. It is the preferred replacement.
• Manifold (elalish/manifold, Apache-2.0) repairs a triangle soup into a guaranteed manifold surface. It fits the embedded library design, and it is the lighter option.
• FOSSIL (szaghi/FOSSIL) implements an alpha wrap API, and it sells a BSD or MIT license for commercial use. The code is Fortran 2003+, and the wrap is a single-pass octree MVP. It does not fit the C++ embedded library design.

Blocklisted wrap tools

• ManifoldPlus (hjwdzh/ManifoldPlus) is non-commercial use only.
• wrapwrap (ipadjen/wrapwrap) uses the AGPL-3 license.
• The 2026 shrink-wrap meshing paper (Scientific Reports) releases no code, thus it is not an option.