<!DOCTYPE HTML>
<html>
<body>
<svg style="width: 250px; height: 144px; border: solid black 1px;">
<text id="label1" x="75" y="30" transform="rotate(10, 75, 34.5)">Sprint 13_March_2015</text>
<text id="label2" x="100" y="30" transform="rotate(10, 100, 34.5)">DT_Apr2015_Sprint13</text>
<polygon id=polygon1 fill="none" stroke="blue" stroke-dasharray="5 5" stroke-width=1 />
<polygon id=polygon2 fill="none" stroke="red" stroke-dasharray="5 5" stroke-width=1 />
</svg>
<br>
<button onClick=testOverlap()>Test Overlap</button>
<script>
function testOverlap()
{
//---show 'native' rects---
var trns1=label1.getAttribute("transform")
label1.removeAttribute("transform")
var bb1=label1.getBBox()
var bb1x=bb1.x
var bb1y=bb1.y
var bb1w=bb1.width
var bb1h=bb1.height
label1.setAttribute("transform",trns1)
var pnts1=[bb1x,bb1y,bb1x,bb1y+bb1h,bb1x+bb1w,bb1y+bb1h,bb1x+bb1w,bb1y]
polygon1.setAttribute("points",pnts1.join())
polygon1.setAttribute("transform",trns1)
//---remove transform from polygon--
ctmPolygon(polygon1)
var trns2=label2.getAttribute("transform")
label2.removeAttribute("transform")
var bb2=label2.getBBox()
var bb2x=bb2.x
var bb2y=bb2.y
var bb2w=bb2.width
var bb2h=bb2.height
label2.setAttribute("transform",trns2)
var pnts2=[bb2x,bb2y,bb2x,bb2y+bb2h,bb2x+bb2w,bb2y+bb2h,bb2x+bb2w,bb2y]
polygon2.setAttribute("points",pnts2.join())
polygon2.setAttribute("transform",trns2)
//---remove transform from polygon--
ctmPolygon(polygon2)
alert(getPolygonIntersect(polygon1,polygon2))
}
//---screen points for polygon---
function ctmPolygon(myPoly)
{
var ctm = myPoly.getCTM()
var svgRoot = myPoly.ownerSVGElement
var pointsList = myPoly.points;
var n = pointsList.numberOfItems;
for(var m=0; m < n; m++)
{
var mySVGPoint = svgRoot.createSVGPoint();
mySVGPoint.x = pointsList.getItem(m).x
mySVGPoint.y = pointsList.getItem(m).y
mySVGPointTrans = mySVGPoint.matrixTransform(ctm)
pointsList.getItem(m).x=mySVGPointTrans.x
pointsList.getItem(m).y=mySVGPointTrans.y
};
myPoly.removeAttribute("transform")
}
function getPolygonIntersect(polygonA,polygonB)
{
var IntPoints=[]
var aPoints=polygonA.points
var m=aPoints.numberOfItems
for(var i=0;i<m;i++)
{
var aX1=aPoints.getItem(i).x
var aY1=aPoints.getItem(i).y
if(i<m-1)
{
var aX2=aPoints.getItem(i+1).x
var aY2=aPoints.getItem(i+1).y
}
else
{
var aX2=aPoints.getItem(0).x
var aY2=aPoints.getItem(0).y
}
var bPoints=polygonB.points
var n=bPoints.numberOfItems
for(var k=0;k<n;k++) //--each side of polygon---
{
var bX1=bPoints.getItem(k).x
var bY1=bPoints.getItem(k).y
if(k<n-1)
{
var bX2=bPoints.getItem(k+1).x
var bY2=bPoints.getItem(k+1).y
}
else
{
var bX2=bPoints.getItem(0).x
var bY2=bPoints.getItem(0).y
}
//---return false or intersect point---
var xy=lineSegIntersect(aX1,aY1,aX2,aY2,bX1,bY1,bX2,bY2)
if(xy)
{
if(IntPoints.join().indexOf(xy)==-1)//--no dups--
{
IntPoints.push(xy)
}
}
}
}
if(IntPoints.length>0)
return true
else
return false
}
//---compare two lines: A.B---
function lineSegIntersect(aX1,aY1,aX2,aY2,bX1,bY1,bX2,bY2)
{
//---compute vectors Va, Vb--------
var Va=( (bX2-bX1)*(aY1-bY1) - (bY2-bY1)*(aX1-bX1) )/ ( (bY2-bY1)*(aX2-aX1) - (bX2-bX1)*(aY2-aY1) )
var Vb=( (aX2-aX1)*(aY1-bY1) - (aY2-aY1)*(aX1-bX1) )/( (bY2-bY1)*(aX2-aX1) - (bX2-bX1)*(aY2-aY1) )
if(Va>0 && Va<1 && Vb>0 && Vb<1)
{
//---intersect true, show point---
var ma=(aY2-aY1)/(aX2-aX1)
var mb=(bY2-bY1)/(bX2-bX1)
if(aX2!=aX1&&bX2!=bX1) //---!vertical line---
{
var x=(aX1*ma-aY1-bX1*mb+bY1)/(ma-mb)
var y=ma*(x-aX1)+aY1
}
else if(aX2==aX1)
{
var x=aX1
var y=mb*(x-bX1)+bY1
}
else if(bX2==bX1)
{
var x=bX1
var y=ma*(x-aX1)+aY1
}
return [x,y]
}
else
return false
}
</script>
</body>
</html>
