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...Orientation in 2D of a point relative to two other points?
Autor: Arash Partow
Homepage: http://www.partow.net
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Tip Rating (10):  
     


function Orientation(x1, y1, x2, y2, Px, Py: Double): Integer;
var 
  
Orin: Double;
begin
  
(* Linear determinant of the 3 points *)
  
Orin := (x2 - x1) * (py - y1) - (px - x1) * (y2 - y1);

  if Orin > 0.0 then Result := +1    (* Orientaion is to the right-hand side  *)
  
else if Orin < 0.0 then Result := -1  (* Orientaion is to the left-hand side   *)
  
else
    
Result := 0;                  (* Orientaion is neutral if result is 0  *)
end;
(* End Of Orientation *)


 

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