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...test if 2 lines cross and find the intersection?
Autor: FastGEO library
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Tip Rating (4):  
     


procedure IntersectionPoint(const x1,y1,x2,y2,x3,y3,x4,y4:Double; out Nx,Ny:Double);
var R : Double;
dx1,dx2,dx3 : Double;
dy1,dy2,dy3 : Double;
begin
  
dx1 := x2 - x1;
  dx2 := x4 - x3;
  dx3 := x1 - x3;
  dy1 := y2 - y1;
  dy2 := y1 - y3;
  dy3 := y4 - y3;
  R:= dx1 * dy3 - dy1 * dx2;

  if R <> 0 then
  begin
    
R := (dy2 * (x4 - x3) - dx3 * dy3) / R;
    Nx := x1 + R * dx1;
    Ny := y1 + R * dy1;
  end else
  begin
    if 
Collinear(x1,y1,x2,y2,x3,y3) then
    begin
      
Nx := x3;
      Ny := y3;
      end
      else
      begin
        
Nx := x4;
        Ny := y4;
      end;
   end;
end;
(* End Of IntersectionPoint *)

function Collinear(const x1,y1,x2,y2,x3,y3:Double):Boolean;
begin
  
Result := IsEqual((x2 - x1) * (y3 - y1) - (x3 - x1) * (y2 - y1),0);
end;
(* End Of Collinear *)



 

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