Cosine angle + convex hull algorithm for line segments

        The angle of two segments by cosine theorem///////Start point///end point///double A            Ngle (PointF o, PointF S, PointF e) {Double COSFI = 0, fi = 0, norm = 0;            Double dsx = s.x-o.x;            Double dsy = s.y-o.y;            Double dex = e.x-o.x;            Double dey = e.y-o.y;            COSFI = DSX * dex + dsy * dey;            Norm = (DSX * dsx + dsy * dsy) * (DEX * dex + dey * dey);            COSFI/= math.sqrt (Norm);            if (COSFI >= 1.0) return 0;            if (COSFI <= -1.0) return Math.PI;            fi = Math.acos (COSFI);            if (Fi/math.pi < +) {return * FI/MATH.PI;            } else {return 360-180 * FI/MATH.PI; }}///<summary>//Convex packet algorithm///</summary>//<param name= "_list" >&lt ;/param>//&LT;RETURNS&GT;&LT;/RETURNS&GT Private list<tuline> Bruteforcetu (list<info> _list) {//record pole pair list<tuline>            role = new list<tuline> (); Traverse for (int i = 0; i < _list. Count-1; i++) {for (int j = i + 1; j < _list. Count; J + +) {Double A = _list[j]. Y-_list[i].                    Y Double b = _list[i]. X-_list[j].                    X Double c = _list[i]. X * _list[j]. Y-_list[i]. Y * _list[j].                    X                    int count = 0; Put all points into the equation for (int k = 0; k < _list. Count; k++) {Double result = a * _list[k]. X + b * _list[k].                        Y-c;                        if (Result > 0) {count++;                        } else if (Result < 0) {count--; }                   }//Is the pole, then the connection is recorded if (Math.Abs (count) = = _list.                        Count-2) {Tuline line = new Tuline ();                        IPoint pi = new Pointclass (); Pi. X = _list[i].                        X Pi. Y = _list[i].                        Y Line.                        Begin = PI;                        IPoint Pj = new Pointclass (); pj.x = _list[j].                        X PJ.Y = _list[j].                        Y Line.                        End = Pj; Role.                    ADD (line);        }}} return role; }

　　

Cosine angle + convex hull algorithm for line segments