So I have tried two methods that should both work with line segments to determine if they are intersecting. The problem is on occasion I get a random false positive, or false negatives.

The commented code was my first attempt the rest of the code was my second attempt.

Found the logic at these sites:

homework - How do you detect where two line segments intersect? - Stack Overflow

Intersection point of two lines

Code:bool C_Line::Lines_Intersect(C_Line l) { /* C_Point r = p1 - p; C_Point q = l.Get_Point1(); C_Point s = l.Get_Point2() - l.Get_Point1(); float RxS = r.Cross_Product(s); if(RxS == 0)return false; float QPxR = (q-p).Cross_Product(r); if(QPxR == 0)return false; float t = (q-p).Cross_Product(s)/RxS; float u = QPxR/RxS; if(t <= 1 && t >=0 && u <= 1 && u >= 0)return true; else return false; */ C_Point A = p; C_Point B = p1; C_Point C = l.Get_Point1(); C_Point D = l.Get_Point2(); int x1 = A.Get_X(); int x2 = B.Get_X(); int x3 = C.Get_X(); int x4 = D.Get_X(); int y1 = A.Get_Y(); int y2 = B.Get_Y(); int y3 = C.Get_Y(); int y4 = D.Get_Y(); float denom = ((y4 - y3)*(x2 - x1)) - ((x4 - x3)*(y2 - y1)); if(denom == 0)return true; float ua = ((x4 - x3)*(y1 - y3) - (y4 - y3)*(x1 - x3)) / denom; float ub = ((x2 - x1)*(y1 - y3) - (y2 - y1)*(x1 - x3)) / denom; if(ua <= 1 && ua >= 0 && ub <= 1 && ub >= 0)return true; else return false; }