Sprite with 24 images needs direction formula?

[Nitrogen]

Here is my code that I use to get an angle:

  Angle := round((180 * (1 + ArcTan2((X1-X2), (Y1-Y2)) / PI)));
  if Angle < 0 then Angle &#58;= 360-Angle;
  if Angle > 360 then Angle &#58;= Angle-360;

ArcTan2 and PI defined in Math.pas

Then you just need something like this:

ImageNumber := round((Angle/360)*NumberOfImages);