@che.js/che.js NPM

What is che.js?

che.js is an implementation of the Compact Half-Edge(CHE) data structure for triangular meshes in Javascript. It is an upgrade on the half-edge data structure, which representes each edge as two twin-edges, each part of a triangle.

Why use che.js?

The main goal of che.js is to provide a scalable structure for meshes, so you can scale your memory usage according to your needs.

che.js is split in 4 levels, each of them increasing the amount of information you have.

Levels

The first level of che.js is the minimal representation of a triangle, all it storages is the geometry informations about the vertices, and which vertices form each triangles. It does that by storing references to vertices in a table called _tableVertices, each triangle of the mesh is represented by 3 vertice references on this table.
The second level of che.js stores the opposites of each half-edge in the mesh, which allows for fast computation of adjacency between triangles.
The third level of the structure chooses an half-edge to represent each vertex and edge. It allows for fast discovery of adjacency with vertices, and a simple way to draw independent edges if needed.
The fourth level adds information about the boundary curves of a mesh, representing each boundary curve with a half-edge.

Getting Started

npm install @che.js/che.js

⚠⚠⚠

Warning: Since che.js uses es6 modules, you have to either name your file with .mjs or explicitly state in your package.json that your project type is "module".

⚠⚠⚠

Loading a mesh

Currently che.js only have loaders available for objects in .ply format with x,y,z coordinates, you can find a few examples at the ply folder available on the root of this repository. In this example, we will use sphere.ply.

import Che from '@che.js/che.js';
import fs from 'fs'

//Load ply file

let plyFile = fs.readFileSync('sphere.ply', 'utf-8');

let cheMesh = new Che()

cheMesh.loadPly(plyFile).then(() => {
  //do whatever you want
})

Finding the vertex star of an vertex

cheMesh.loadPly(plyFile).then(() => {
  let start = performance.now()
  let vertexStarOfVertex3 = cheMesh.relation00(3);
  let end = performance.now()
  console.log(`L0 R00: ${end - start}`)
  console.log(vertexStarOfVertex3);

  cheMesh.loadCheL1();
  start = performance.now()
  vertexStarOfVertex3 = cheMesh.relation00(3);
  end = performance.now()
  console.log(`L1 R00: ${end - start}`)
  console.log(vertexStarOfVertex3);


  cheMesh.loadCheL2();
  start = performance.now()
  vertexStarOfVertex3 = cheMesh.relation00(3);
  end = performance.now()
  console.log(`L2 R00: ${end - start}`)
  console.log(vertexStarOfVertex3);
})