ecmascript:

function tracePrint (text)
{
	if (traceEnabled) Browser.println ('[HeadsUpDisplayPrototype VisibilityControlScript] ' + text);
}
function setIsVisible (value, timeStamp)
{
	isVisible = value;
	tracePrint('isVisible=' + value);
}
function setPlaneSensorIsActive (value, timeStamp)
{
	tracePrint('PlaneSensor isActive=' + value);

	if (value == false)
	{
		tracePrint('planeSensorTranslation=' + planeSensorTranslation);
		if (isVisible)
		{
			translationChanged = planeSensorTranslation;
		}
		else
		{
			// fell off screen, reset to center
			translationChanged = new SFVec3f(0, 0, 0);
			translationOffsetChanged  = new SFVec3f(0, 0, 0);
		}
	}
}
function setPlaneSensorTranslation (value, timeStamp)
{
	planeSensorTranslation = value;
	tracePrint('planeSensorTranslation=' + value);
}