Mega Code Archive
How to Rotate a 2D Point around another 2D Point
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Title: How to Rotate a 2D Point around another 2D Point
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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