Design a class Line that implements a line, which is represented by the formula

Question

Design a class Line that implements a line, which is represented by the formula y = ax+b. Your class should store a and b as double member variables. Write a member function intersect(L) that returns the x coordinate at which this line intersects line L. If the two lines are parallel, then your function should return a message " Parallel" and exit. Write a C++ program that creates a number of Line objects and tests each pair for intersection. Your program should print an appropriate error message for parallel lines.

Explanation / Answer

  bool LineCollision( const Point& A1, const Point& A2,                      const Point& B1, const Point& B2,                      double* out                                )  {      Point a(A2-A1);      Point b(B2-B1);        double f = PerpDot(a,b);      if(!f)      // lines are parallel          return false;        Point c(B2-A2);      double aa = PerpDot(a,c);      double bb = PerpDot(b,c);        if(f < 0)      {          if(aa > 0)     return false;          if(bb > 0)     return false;          if(aa < f)     return false;          if(bb < f)     return false;      }      else      {          if(aa < 0)     return false;          if(bb < 0)     return false;          if(aa > f)     return false;          if(bb > f)     return false;      }        if(out)          *out = 1.0 - (aa / f);      return true;  }  

  bool LineCollision( const Point& A1, const Point& A2,                      const Point& B1, const Point& B2,                      Point* out                                )  {      //...        if(out)          *out = (b * (1.0 - (aa / f))) + B1;  // this could probably be simplified -- but I'm lazy      return true;  }  

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