code: function (m) {
      if (m !== undefined) {
         // TODO Check for type and length
          this.m = m;
      } else {
          m = new Float32Array(16);
          m[0] = 1.0;
          m[1] = 0.0;
          m[2] = 0.0;
          m[3] = 0.0;
          m[4] = 0.0;
          m[5] = 1.0;
          m[6] = 0.0;
          m[7] = 0.0;
          m[8] = 0.0;
          m[9] = 0.0;
          m[10] = 1.0;
          m[11] = 0.0;
          m[12] = 0.0;
          m[13] = 0.0;
          m[14] = 0.0;
          m[15] = 1.0;
          this.m = m;
      }
  }
docs: Construct a 4x4 matrix.