Waving Image

The method used to make this image wave, or oscillate, is the same as used in my Jolly Roger and American Flag movies. The only difference is that I am using a different image.

The image is divided up into narrow vertical strips using masks. Then the strips are rotated slightly using sin waves. This produces apparent motion in both the x and y directions.

The motion propagates from the left edge of the flag to the right edge, producing the effect that the wind is blowing from the left.

The function that animates the flag reads as follows:

function myWaveFlag(evt)
{
  for (var i = kNbrStrips-1; i>0; --i) {
    flags[i].rotation = flags[i-1].rotation;
  }
  var t = getTimer();
  flags[0].rotation = Math.sin(t*.001+Math.cos(t*.0005)*Math.PI*2)*2;
}