code: function buildStars(numVerts, cells) {
    var stars = new Array(numVerts)
    for(var i=0; i<numVerts; ++i) {
      stars[i] = []
    }
    var numCells = cells.length
    for(var i=0; i<numCells; ++i) {
      var f = cells[i]
      for(var j=0; j<3; ++j) {
        stars[f[j]].push(i)
      }
    }
    return stars
  }
docs: Construct all stars of a mesh