code: function reshape(gl, width, height)
  {
     var h = height / width;
     gl.Viewport(0, 0, width, height);
     gl.MatrixMode(gl.PROJECTION);
     gl.LoadIdentity();
     gl.Frustum(-1.0, 1.0, -h, h, 5.0, 60.0);
     gl.MatrixMode(gl.MODELVIEW);
     gl.LoadIdentity();
     gl.Translatef(0.0, 0.0, -40.0);
     gl.Scalef(0.1, 0.1, 0.1);
     gl.render();
  }
docs: /* new window size or exposure