var instructionsDiv=document.getElementById('instructions');var mapDiv=document.getElementById('map');var areaDiv=document.getElementById('area');var pedometerItem=document.getElementById('pedometer');var map;var points=[];var markers=[];var lines=[];var polygonPoints=[];var polygon=null;var lineWidth=5;var lineColor='#ff0000';var closerColor='#0000ff';var fillColor='#009900';var redIcon=new GIcon(G_DEFAULT_ICON);redIcon.image='http://www.acme.com/resources/images/markers/red.PNG';redIcon.shadow='http://www.acme.com/resources/images/markers/shadow.PNG';redIcon.iconSize=new GSize(20,34);redIcon.shadowSize=new GSize(37,34);redIcon.iconAnchor=new GPoint(9,34);redIcon.infoWindowAnchor=new GPoint(9,2);redIcon.infoShadowAnchor=new GPoint(18,25);var blueIcon=new GIcon(redIcon);blueIcon.image='http://www.acme.com/resources/images/markers/blue.PNG';function Setup()
{try
{if(!GBrowserIsCompatible())
{mapDiv.innerHTML='Sorry, your browser is not compatible with Google Maps.';return;}
map=new GMap2(mapDiv,{draggableCursor:'default'});map.addControl(new GLargeMapControl());map.addMapType(WMS_TOPO_MAP);map.addMapType(WMS_DOQ_MAP);map.addControl(new GMapTypeControl());map.addControl(new GScaleControl());GEvent.addListener(map,'click',MapClick);SavePositionZoomTypeCookieOnChanges(map);if(!GetPositionZoomTypeCookie(map))
{var point=GetPointFromIP();if(point!=null)
map.setCenter(point,9);else
map.setCenter(new GLatLng(0.0,0.0),1);}
map.setMapType(G_NORMAL_MAP);GEvent.addListener(map,'moveend',UpdatePedometerLink);GEvent.addListener(map,'zoomend',UpdatePedometerLink);GEvent.addListener(map,'maptypechanged ',UpdatePedometerLink);UpdatePedometerLink();Display();}
catch(e)
{GLog.write('Setup:\n'+Props(e));}}
function UpdatePedometerLink()
{var mapCenter=map.getCenter();var mapZoom=map.getZoom();var mapTypeLetter=MapTypeToLetter(map.getCurrentMapType());mapTypeLetter=mapTypeLetter.toLowerCase();pedometerItem.innerHTML='<a href="http://www.gmap-pedometer.com/?centerX='+mapCenter.lng()+'&centerY='+mapCenter.lat()+'&zl='+mapZoom+'&fl='+mapTypeLetter+'">Gmaps Pedometer</a><br />';}
function Display()
{for(var i=0;i<markers.length;++i)
map.removeOverlay(markers[i]);markers=[];for(var i=0;i<lines.length;++i)
map.removeOverlay(lines[i]);lines=[];polygonPoints=[];if(polygon!=null)
{map.removeOverlay(polygon);polygon=null;}
for(var i=0;i<points.length;++i)
{var marker=new GMarker(points[i],{icon:i==points.length-1?blueIcon:redIcon});markers.push(marker);map.addOverlay(marker);GEvent.addListener(marker,'click',MakeCaller(MarkerClick,i));if(i>0&&points.length>=3)
AddPolylines(lines,GreatCirclePoints(points[i-1],points[i]),lineColor,lineWidth);}
if(points.length>=2)
AddPolylines(lines,GreatCirclePoints(points[points.length-1],points[0]),closerColor,lineWidth);if(points.length>=3)
{polygon=new GPolygon(polygonPoints,lineColor,0,0,fillColor,0.5);map.addOverlay(polygon);}
var smallFontOpen='<font size="-1">';var fontClose='</font>';var mapInst='Drag the map with your mouse, or double-click to center.';var clickInst='Click on the map to place points.';var html=smallFontOpen+mapInst+'<p>'+clickInst;areaDiv.innerHTML='&nbsp;';if(points.length<=2)
html+='<p>Once you have placed at least three points, the enclosed area will be computed.';else
{html+='<p>The enclosed area is shown below.';var areaMeters2=SphericalPolygonAreaMeters2(points);if(areaMeters2<1000000.0)
areaMeters2=PlanarPolygonAreaMeters2(points);areaDiv.innerHTML=smallFontOpen+Areas(areaMeters2)+fontClose;}
html+=fontClose;instructionsDiv.innerHTML=html;}
function AddPolylines(lines,ps,lineColor,lineWidth)
{var line=new GPolyline(ps,lineColor,lineWidth);lines.push(line);map.addOverlay(line);for(var i=0;i<ps.length;++i)
polygonPoints.push(ps[i]);}
var metersPerKm=1000.0;var meters2PerHectare=10000.0;var feetPerMeter=3.2808399;var feetPerMile=5280.0;var acresPerMile2=640;function Areas(areaMeters2)
{var areaHectares=areaMeters2/meters2PerHectare;var areaKm2=areaMeters2/metersPerKm/metersPerKm;var areaFeet2=areaMeters2*feetPerMeter*feetPerMeter;var areaMiles2=areaFeet2/feetPerMile/feetPerMile;var areaAcres=areaMiles2*acresPerMile2;return areaMeters2.toPrecision(4)+' m&sup2; / '+areaHectares.toPrecision(4)+' hectares / '+areaKm2.toPrecision(4)+' km&sup2; / '+areaFeet2.toPrecision(4)+' ft&sup2; / '+areaAcres.toPrecision(4)+' acres / '+areaMiles2.toPrecision(4)+' mile&sup2;';}
var earthRadiusMeters=6367460.0;var metersPerDegree=2.0*Math.PI*earthRadiusMeters/360.0;function GreatCirclePoints(p1,p2)
{var maxDistanceMeters=200000.0;var ps=[];if(p1.distanceFrom(p2)<=maxDistanceMeters)
{ps.push(p1);ps.push(p2);}
else
{var theta1=p1.lng()*radiansPerDegree;var phi1=(90.0-p1.lat())*radiansPerDegree;var x1=earthRadiusMeters*Math.cos(theta1)*Math.sin(phi1);var y1=earthRadiusMeters*Math.sin(theta1)*Math.sin(phi1);var z1=earthRadiusMeters*Math.cos(phi1);var theta2=p2.lng()*radiansPerDegree;var phi2=(90.0-p2.lat())*radiansPerDegree;var x2=earthRadiusMeters*Math.cos(theta2)*Math.sin(phi2);var y2=earthRadiusMeters*Math.sin(theta2)*Math.sin(phi2);var z2=earthRadiusMeters*Math.cos(phi2);var x3=(x1+x2)/2.0;var y3=(y1+y2)/2.0;var z3=(z1+z2)/2.0;var r3=Math.sqrt(x3*x3+y3*y3+z3*z3);var theta3=Math.atan2(y3,x3);var phi3=Math.acos(z3/r3);var p3=new GLatLng(90.0-phi3*degreesPerRadian,theta3*degreesPerRadian);var s1=GreatCirclePoints(p1,p3);var s2=GreatCirclePoints(p3,p2);for(var i=0;i<s1.length;++i)
ps.push(s1[i]);for(var i=1;i<s2.length;++i)
ps.push(s2[i]);}
return ps;}
function PlanarPolygonAreaMeters2(points)
{var a=0.0;for(var i=0;i<points.length;++i)
{var j=(i+1)%points.length;var xi=points[i].lng()*metersPerDegree*Math.cos(points[i].lat()*radiansPerDegree);var yi=points[i].lat()*metersPerDegree;var xj=points[j].lng()*metersPerDegree*Math.cos(points[j].lat()*radiansPerDegree);var yj=points[j].lat()*metersPerDegree;a+=xi*yj-xj*yi;}
return Math.abs(a/2.0);}
function SphericalPolygonAreaMeters2(points)
{var totalAngle=0.0;for(i=0;i<points.length;++i)
{var j=(i+1)%points.length;var k=(i+2)%points.length;totalAngle+=Angle(points[i],points[j],points[k]);}
var planarTotalAngle=(points.length-2)*180.0;var sphericalExcess=totalAngle-planarTotalAngle;if(sphericalExcess>420.0)
{totalAngle=points.length*360.0-totalAngle;sphericalExcess=totalAngle-planarTotalAngle;}
else if(sphericalExcess>300.0&&sphericalExcess<420.0)
{sphericalExcess=Math.abs(360.0-sphericalExcess);}
return sphericalExcess*radiansPerDegree*earthRadiusMeters*earthRadiusMeters;}
function Angle(p1,p2,p3)
{var bearing21=Bearing(p2,p1);var bearing23=Bearing(p2,p3);var angle=bearing21-bearing23;if(angle<0.0)
angle+=360.0;return angle;}
var clicked=false,doubleClicked;function MapClick(overlay,point)
{try
{if(overlay==null&&point!=null)
{if(clicked)
doubleClicked=true;else
{clicked=true;doubleClicked=false;setTimeout(MakeCaller(MapClickLater,point),250);}}}
catch(e)
{GLog.write('MapClick:\n'+Props(e));}}
function MapClickLater(point)
{try
{if(!doubleClicked)
{points.push(point);Display();}
clicked=false;}
catch(e)
{GLog.write('MapClickLater:\n'+Props(e));}}
function MarkerClick(pointIndex)
{try
{RotatePoints(pointIndex+1);Display();}
catch(e)
{GLog.write('MarkerClick:\n'+Props(e));}}
function RotatePoints(n)
{var t=[];for(var i=0;i<points.length;++i)
t.push(points[(i+n)%points.length]);points=t;}
function DeleteLastPoint()
{if(points.length>0)
points.length--;Display();}
function ClearAllPoints()
{points=[];Display();}