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...Determine the point at which two 2D segments intersect?
Autor: Arash Partow
Homepage: http://www.partow.net
[ Print tip ]  

Tip Rating (9):  
     


procedure IntersectPoint(x1, y1, x2, y2, x3, y3, x4, y4: Double; var 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;



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

// calcule le point d'intersection de 2 droites bidimensionnelles


 

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