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...Rotate a 2D Point around another 2D Point?
Autor: Arash Partow
Homepage: http://www.partow.net
[ Print tip ]  

Tip Rating (7):  
     


const
  
PIDiv180 = 0.017453292519943295769236907684886;

procedure Rotate(RotAng: Double; x, y, ox, oy: Double; var Nx, Ny: Double);
begin
  
Rotate(RotAng, x - ox, y - oy, Nx, Ny);
  Nx := Nx + ox;
  Ny := Ny + oy;
end;
(* End Of Rotate Cartesian Point About Origin *)


procedure Rotate(RotAng: Double; x, y: Double; var Nx, Ny: Double);
var
  
SinVal: Double;
  CosVal: Double;
begin
  
RotAng := RotAng * PIDiv180;
  SinVal := Sin(RotAng);
  CosVal := Cos(RotAng);
  Nx := x * CosVal - y * SinVal;
  Ny := y * CosVal + x * SinVal;
end;
(* End Of Rotate Cartesian Point*)

 

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