Class GenericObserver

Observes a Subject; when the Subject broadcasts a SubjectEvent then this executes a specified function.

Example 1

Here is an example of a GenericObserver that prints any event broadcast by a Clock:

var obs = new GenericObserver(clock, evt => println('event='+evt));
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Paste that code into the Terminal command line of any application, or try this link. which contains the above code running in the pendulum simulation. Click the rewind, play, and step buttons to see events in the Terminal output area.

Use the following Terminal command to turn off the GenericObserver:

clock.removeObserver(obs);
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Example 2

This prints only when a particular Clock event occurs:

var obs = new GenericObserver(clock, evt => {
    if (evt.nameEquals(Clock.CLOCK_PAUSE)) {
      println('event='+evt);
    }
});
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Paste that code into the Terminal command line of any application, or try this link which contains the above code running in the pendulum simulation. Click the pause button to see events in the Terminal output area.

Example 3

This sets color of a contact force line according to gap distance: red = zero distance, green = max distance. This is useful to study the effects of using different settings for ExtraAccel.

new GenericObserver(displayList, evt => {
  if (evt.nameEquals(DisplayList.OBJECT_ADDED)) {
    var obj = evt.getValue();
    if (obj instanceof DisplayLine) {
      var f = obj.getSimObjects()[0];
      if (f.getName().match(/^CONTACT_FORCE1/)) {
        var pct = Math.max(0,
            Math.min(1, f.contactDistance/f.contactTolerance));
        obj.setColor(Util.colorString3(1-pct, pct, 0));
      }
    }
  }
});
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The above script can be entered into the Terminal command line of most applications which use ContactSim. Or try this link which contains the above code running in ContactApp. That link also sets EXTRA_ACCEL=none so you will see the gap distance color vary periodically.