/* Creation date: 2/13/2006 */

//---------------------------Botton Line ------------------------------------//

var bottom = "<br><br><div align='center'><font size='1'><a href='index.html'><b>HOME</b></a> &nbsp; &nbsp; &nbsp;<a href='legal.html'>© 2006-2009 West Groton Company - All rights reserved</a> &nbsp; &nbsp; &nbsp; <a href='contact.html'>Contact Me</a></font></div><br><br>";

function valButton(btn) {
    var cnt = -1;
    for (var i=btn.length-1; i > -1; i--) {
        if (btn[i].checked) {cnt = i; i = -1;}
    }
    if (cnt > -1) return btn[cnt].value;
    else return null;
}
      
//--------------------Muzzle Energy Calculator Script -----------------------//

function calc() {
  var grains_per_lb = 7000;
  var lb_per_slug = 32.17;
  var grains_per_slug = grains_per_lb * lb_per_slug;
  var pi = 3.141592654;
  var velocity = new Number(document.mainform.velocity.value);
  var weight = new Number(document.mainform.weight.value);
  var bullet = valButton(document.mainform.bullet)*1;
  var diameter = new Number(document.mainform.diameter.value);
  var energy = 0.5 * (weight / grains_per_slug) * velocity * velocity;
  var r = diameter / 2;
  var knockdown = energy * Math.PI * r * r * 2.54 * bullet;
  var secdens = (weight / grains_per_lb) / (diameter * diameter);
  var jem = energy * secdens;
  document.mainform.energy.value = Math.round(energy);
  document.mainform.knockdown.value = Math.round(knockdown)+"%";
  document.mainform.secdens.value = round(secdens, 3);
  document.mainform.jem.value = Math.round(jem);
}

function wchg() {
  calc();
}

function dchg() {
  calc();
}

function vchg() {
  calc();
}

function bchg() {
  calc();
}
function round(x, places) {
  fac = Math.pow(10, places);
  return Math.round(x * fac) / fac
}

function modify(weight, velocity, diameter) {
  document.mainform.weight.value = weight
  document.mainform.velocity.value = velocity;
  document.mainform.diameter.value = diameter;
  calc();
}


//-----------------------------Redirect Script--------------------------------//


function FourOhFourRedirect(url, msg)
{
   var TARG_ID = "COOL_REDIRECT";
   var DEF_MSG = "Redirecting...";

   if( ! msg )
   {
      msg = DEF_MSG;
   }

   if( ! url )
   {
      throw new Error('You didn\'t include the "url" parameter');
   }


   var e = document.getElementById(TARG_ID);

   if( ! e )
   {
      throw new Error('"COOL_REDIRECT" element id not found');
   }

   var cTicks = parseInt(e.innerHTML);

   var timer = setInterval(function()
   {
      if( cTicks )
      {
         e.innerHTML = --cTicks;
      }
      else
      {
         clearInterval(timer);
         document.body.innerHTML = msg;
         location = url;	  
      }

   }, 1000);
}