code: function() {
      var indexer = new Indexer();
      for (var i = 0; i < this.triangles.length; i++) {
        var t = this.triangles[i];
        for (var j = 0; j < t.length; j++) {
          var a = t[j], b = t[(j + 1) % t.length];
          indexer.add([Math.min(a, b), Math.max(a, b)]);
        }
      }
      if (!this.lines) this.addIndexBuffer('lines');
      this.lines = indexer.unique;
      this.compile();
      return this;
    }
docs: ### .computeWireframe()  Populate the `lines` index buffer from the `triangles` index buffer.