/**
  * ======================================================
  * IDEA (Infusing Satellite Data Into Environmental Apps) 
  * ======================================================
  * - aerosol.js version 0.1.0
  * - Author: Chad Rhyner (chad.rhyner@ssec.wisc.edu) 
  * - Updated On: November 29, 2007
  * - Contains the javascript to make the images fade in
  *   and fade out for the aerosol project.
  * ======================================================
  * - Super: Bill Bellon (bill.bellon@ssec.wisc.edu)
  * ======================================================
  */

/**
 * updateOp( )
 * takes in a value between 1-100, and sets the opacity
 * of the topImg, and bottomImg elts in the document.
 */
function updateOp( opFactor ) {
   var topImg0    = document.getElementById("topImg0");
   var topImg1    = document.getElementById("topImg1");
		
   var opacityValPercent = opFactor;        // IE7
   var opacityVal        = parseFloat(opFactor / 100);  // Firefox

   // IE7 Setting
   topImg0.style.filter     = "alpha(opacity=" + String(opacityValPercent) + ");";  
   topImg1.style.filter     = "alpha(opacity=" + String(opacityValPercent) + ");";  
   // Firefox Setting
   topImg0.style.opacity    = String(opacityVal) + ";";            
   topImg1.style.opacity    = String(opacityVal) + ";";            

   return;
}