 // location
      2,            // size (num values to pull from buffer per iteration)
      gl.FLOAT,     // type of data in buffer
      false,        // normalize
      0,            // stride (0 = compute from size and type above)
      0,            // offset in buffer
  );

  const numInstances = 5;
  const matrices = [
    m4.identity(),
    m4.identity(),
    m4.identity(),
    m4.identity(),
    m4.identity(),
  ];

  const colors = [
    [ 1, 0, 0, 1, ],  // red
    [ 0, 1, 0, 1, ],  // green
   