intersection-min.js

  function Point2D(x,y){if(arguments.length>0){this.x=x;this.y=y;}}
  Point2D.prototype.clone=function(){return new Point2D(this.x,this.y);};Point2D.prototype.add=function(that){return new Point2D(this.x+that.x,this.y+that.y);};Point2D.prototype.addEquals=function(that){this.x+=that.x;this.y+=that.y;return this;};Point2D.prototype.offset=function(a,b){var result=0;if(!(b.x<=this.x||this.x+a.x<=0)){var t=b.x*a.y-a.x*b.y;var s;var d;if(t>0){if(this.x<0){s=this.x*a.y;d=s/a.x-this.y;}else if(this.x>0){s=this.x*b.y;d=s/b.x-this.y}else{d=-this.y;}}else{if(b.x<this.x+a.x){s=(b.x-this.x)*a.y;d=b.y-(this.y+s/a.x);}else if(b.x>this.x+a.x){s=(a.x+this.x)*b.y;d=s/b.x-(this.y+a.y);}else{d=b.y-(this.y+a.y);}}
  if(d>0){result=d;}}
  return result;};Point2D.prototype.rmoveto=function(dx,dy){this.x+=dx;this.y+=dy;};Point2D.prototype.scalarAdd=function(scalar){return new Point2D(this.x+scalar,this.y+scalar);};Point2D.prototype.scalarAddEquals=function(scalar){this.x+=scalar;this.y+=scalar;return this;};Point2D.prototype.subtract=function(that){return new Point2D(this.x-that.x,this.y-that.y);};Point2D.prototype.subtractEquals=function(that){this.x-=that.x;this.y-=that.y;return this;};Point2D.prototype.scalarSubtract=function(scalar){return new Point2D(this.x-scalar,this.y-scalar);};Point2D.prototype.scalarSubtractEquals=function(scalar){this.x-=scalar;this.y-=scalar;return this;};Point2D.prototype.multiply=function(scalar){return new Point2D(this.x*scalar,this.y*scalar);};Point2D.prototype.multiplyEquals=function(scalar){this.x*=scalar;this.y*=scalar;return this;};Point2D.prototype.divide=function(scalar){return new Point2D(this.x/scalar,this.y/scalar);};Point2D.prototype.divideEquals=function(scalar){this.x/=scalar;this.y/=scalar;return this;};Point2D.prototype.compare=function(that){return(this.x-that.x||this.y-that.y);};Point2D.prototype.eq=function(that){return(this.x==that.x&&this.y==that.y);};Point2D.prototype.lt=function(that){return(this.x<that.x&&this.y<that.y);};Point2D.prototype.lte=function(that){return(this.x<=that.x&&this.y<=that.y);};Point2D.prototype.gt=function(that){return(this.x>that.x&&this.y>that.y);};Point2D.prototype.gte=function(that){return(this.x>=that.x&&this.y>=that.y);};Point2D.prototype.lerp=function(that,t){return new Point2D(this.x+(that.x-this.x)*t,this.y+(that.y-this.y)*t);};Point2D.prototype.distanceFrom=function(that){var dx=this.x-that.x;var dy=this.y-that.y;return Math.sqrt(dx*dx+dy*dy);};Point2D.prototype.min=function(that){return new Point2D(Math.min(this.x,that.x),Math.min(this.y,that.y));};Point2D.prototype.max=function(that){return new Point2D(Math.max(this.x,that.x),Math.max(this.y,that.y));};Point2D.prototype.toString=function(){return this.x+","+this.y;};Point2D.prototype.setXY=function(x,y){this.x=x;this.y=y;};Point2D.prototype.setFromPoint=function(that){this.x=that.x;this.y=that.y;};Point2D.prototype.swap=function(that){var x=this.x;var y=this.y;this.x=that.x;this.y=that.y;that.x=x;that.y=y;};

  function Intersection(status){if(arguments.length>0){this.init(status);}}
  Intersection.prototype.init=function(status){this.status=status;this.points=new Array();};Intersection.prototype.appendPoint=function(point){this.points.push(point);};Intersection.prototype.appendPoints=function(points){this.points=this.points.concat(points);};Intersection.intersectLineLine=function(a1,a2,b1,b2){var result;var ua_t=(b2.x-b1.x)*(a1.y-b1.y)-(b2.y-b1.y)*(a1.x-b1.x);var ub_t=(a2.x-a1.x)*(a1.y-b1.y)-(a2.y-a1.y)*(a1.x-b1.x);var u_b=(b2.y-b1.y)*(a2.x-a1.x)-(b2.x-b1.x)*(a2.y-a1.y);if(u_b!=0){var ua=ua_t/u_b;var ub=ub_t/u_b;if(0<=ua&&ua<=1&&0<=ub&&ub<=1){result=new Intersection("Intersection");result.points.push(new Point2D(a1.x+ua*(a2.x-a1.x),a1.y+ua*(a2.y-a1.y)));}else{result=new Intersection("No Intersection");}}else{if(ua_t==0||ub_t==0){result=new Intersection("Coincident");}else{result=new Intersection("Parallel");}}
  return result;};Intersection.intersectLinePolygon=function(a1,a2,points){var result=new Intersection("No Intersection");var length=points.length;for(var i=0;i<length;i++){var b1=points[i];var b2=points[(i+1)%length];var inter=Intersection.intersectLineLine(a1,a2,b1,b2);result.appendPoints(inter.points);}
  if(result.points.length>0)result.status="Intersection";return result;};Intersection.intersectPolygonPolygon=function(points1,points2){var result=new Intersection("No Intersection");var length=points1.length;for(var i=0;i<length;i++){var a1=points1[i];var a2=points1[(i+1)%length];var inter=Intersection.intersectLinePolygon(a1,a2,points2);result.appendPoints(inter.points);}
  if(result.points.length>0)
  result.status="Intersection";return result;};