remesh

A surface with even triangles, laid over a mesh that has bad ones: the tailor's DUMMY. A body from a file (a scan, an AI model) is long slivers and islands split along its UV seams, and cloth cut from it inherits both. This builds a new surface of nearly equilateral triangles at the edge length you ask for and pulls it onto the old one, so the cloth is cut from good topology whatever the body was made of.

import { remesh } from 'tosijs-3d'
const dummy = remesh(body.positions, body.indices, { edge: 0.02 })
dummy.positions   // on the body's surface
dummy.ref         // each vertex's body triangle (three vertices)...
dummy.weight      // ...and where on it (barycentric)
dummy.project(x, y, z)  // any point onto the body, as the same pair

THE SIZE FOLLOWS THE SHAPE. One edge length cannot do a body: 2 cm is right for a torso and wider than a finger, so a glove came out as mittens. Where the body is thin, each point's target is perRadius times its radius there (the largest ball inside the skin under it): about 6 mm on a finger or a toe, the full edge on an arm or a chest, never below minEdge. It grows no faster than half a metre per metre across the surface, so the triangles grade from hand to arm instead of jumping. Thickness, not curvature: a scan's bumps curve tightly everywhere and asked for tiny triangles all over.

It is Botsch and Kobbelt's isotropic remeshing (2004), each pass:

• split every edge longer than 4/3 of the target at its middle;
• collapse every edge shorter than 4/5 of it, unless that would make an edge too long, fold a triangle over or pinch the surface;
• flip edges toward six edges at every vertex (four on a boundary);
• relax each vertex toward the middle of its neighbours, along the surface only;
• project every vertex back onto the original surface (its nearest point, through mesh-sdf).

The input is welded first (vertices at one position become one), so UV seams do not survive into it. Boundary vertices stay where they are and boundary edges are never collapsed or flipped, so holes (eyes, a cut-off neck) keep their shape. An edge shared by three or more triangles is left alone too.

Pure: positions xyz and triangles in threes in, counter-clockwise outward; the result has the same winding.