XNA - Weird bug with 2D Sprite Rotation

Question

I have a problem with my XNA Game, I have a function where I need my sprite to face towards an enemy, using this code:

        Vector2 currentPosition = Position;
        Vector2 nearestEnemy = gameObjectManager.GetNearestEnemy(Position, GameObjectTypes.Zombie);

        Orientation = (float)Math.Atan2(nearestEnemy.Y - currentPosition.Y, nearestEnemy.X - currentPosition.X)

As found on an XNA forum results in my character looking 90 degrees away from the enemy.

Adding "MathHelper.ToRadians(90);" to the end of my Orientation assignment fixes this bug, why is this happening?

Thanks!

Answer 1

It seems to me that your sprite may be incorrectly oriented in the source file. Atan2, I believe, returns the angle of the given vector, where zero indicates a vector pointing "to the right" (+X, Y=0). If your sprite file does not point "to the right", you will have to make angle corrections.