Reusable code for complex geometry problems

Author: MeghaSharma21

geometry/basicGeometry.sublime-snippet

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+<snippet>
+	<content><![CDATA[
+	typedef complex<double> point;
+	#define x real()
+	#define y imag()
+	
+	double dot(point a,point b){ return (conj(a)*b).x ; }
+	double cross(point a,point b){ return (conj(a)*b).y ; }
+
+	double dist(point a, point b){ return abs(a-b); }			//distance btw points a and b
+
+	double dist(point a, point b, point c, bool issegment = false){		//distance btw line ab and point c
+		double d = cross(b-a,c-a)/dist(a,b) ;
+		if( issegment == true )						// if line is a segment, issegment is true
+		{
+			double dt1 = dot(b-a,c-b) ;
+			if( dt1 > 0 )  return dist(b,c);
+			double dt2 = dot(a-b,c-a) ;
+			if( dt2 > 0 )  return dist(a,c);
+		}
+
+		return abs(d) ;
+	}
+
+	bool cmp(point& a, point& b)
+	{
+		if ( a.x == b.x )
+		{
+			return a.y < b.y ;
+		}
+		else
+		{
+			return a.x < b.x ;
+		}
+	}
+
+	template<class T>
+	istream& operator>> (istream& is, complex<T>& p){
+	   T value;
+	   is >> value;
+	   p.real(value);
+	   is >> value;
+	   p.imag(value);
+	   return is;
+	}
+]]></content>
+	<!-- Optional: Set a tabTrigger to define how to trigger the snippet -->
+	<tabTrigger>geometry-basic</tabTrigger>
+	<!-- Optional: Set a scope to limit where the snippet will trigger -->
+	<!-- <scope>source.python</scope> -->
+</snippet>

geometry/convexHull.sublime-snippet

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+<snippet>
+	<content><![CDATA[
+	//  Convex Hull - Returns vector of points belonging to hull in anti-clockwise order.
+	typedef complex<double> point;
+	#define x real()
+	#define y imag()
+
+	double dot(point a,point b){ return (conj(a)*b).x ; }
+	double cross(point a,point b){ return (conj(a)*b).y ; }
+
+	double dist(point a, point b){ return abs(a-b); }			//distance btw points a and b
+
+	double dist(point a, point b, point c, bool issegment = false){		//distance btw line ab and point c
+		double d = cross(b-a,c-a)/dist(a,b) ;
+		if( issegment == true )						// if line is a segment, issegment is true
+		{
+			double dt1 = dot(b-a,c-b) ;
+			if( dt1 > 0 )  return dist(b,c);
+			double dt2 = dot(a-b,c-a) ;
+			if( dt2 > 0 )  return dist(a,c);
+		}
+
+		return abs(d) ;
+	}
+
+	template<class T>
+	istream& operator>> (istream& is, complex<T>& p){
+	   T value;
+	   is >> value;
+	   p.real(value);
+	   is >> value;
+	   p.imag(value);
+	   return is;
+	}
+
+	bool cmp(point& a, point& b)
+	{
+		if ( a.x == b.x )
+		{
+			return a.y < b.y ;
+		}
+		else
+		{
+			return a.x < b.x ;
+		}
+	}
+
+
+	vector<point> hull(vector<point> P)
+	{
+	   int n = P.size() ;
+	   int k = 0;
+	   vector<point> H(2*n) ;
+
+	   sort( all(P), cmp );
+
+	   for (int  i = 0;  i < n;  i++) {			// lower monotone chain
+			while( k>=2 && cross( H[k-1]-H[k-2], P[i]-H[k-2] ) <= 0)
+					k--;
+			H[k++] = P[i] ;
+	   }
+
+	   for (int  i = n-2, t=k+1;  i >= 0;  i--) {		// upper monotone chain
+			while( k>=t && cross( H[k-1]-H[k-2], P[i]-H[k-2] ) <= 0)
+					k--;
+			H[k++] = P[i];
+	   }
+
+	   H.resize(k-1);
+	   return H;
+	}
+
+]]></content>
+	<!-- Optional: Set a tabTrigger to define how to trigger the snippet -->
+	<tabTrigger>convex-hull</tabTrigger>
+	<!-- Optional: Set a scope to limit where the snippet will trigger -->
+	<!-- <scope>source.python</scope> -->
+</snippet>

geometry/polygonArea.sublime-snippet

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+<snippet>
+	<content><![CDATA[
+	// Area of polygon whose perimeter points are given in order in array
+	vector< point > p;
+
+	double polyarea(){
+		double area = 0;
+		int n = p.size();
+		for(int i=1; i+1<n ; i++ )
+		{
+			point v1 = p[i] - p[0] ;	//taking 0th point as origin
+			point v2 = p[i+1] - p[0] ;
+			area += cross(v1,v2) ;
+		}
+		return abs(area/2.0);
+	}
+]]></content>
+	<!-- Optional: Set a tabTrigger to define how to trigger the snippet -->
+	<tabTrigger>polygon-area</tabTrigger>
+	<!-- Optional: Set a scope to limit where the snippet will trigger -->
+	<!-- <scope>source.python</scope> -->
+</snippet>