/// <summary>
/// Builds an array of <see cref="Vector2"/> containing the normals used for the SAT algorithm for this <see cref="RectangleF"/> instance.
/// </summary>
/// <remarks>
/// The array only contains the top and right normals as the bottom and left normals are the same (just rotated 180 degrees).
/// </remarks>
/// <returns>Array of normal vectors.</returns>
private Vector2[] GetSATNormals()
{
Vector2[] normalVectors = new Vector2[4];
normalVectors[0] = Vector2Helper.VectorFromRotation(this.Rotation);
normalVectors[1] = normalVectors[0].Rotate(MathHelper.PiOver2);
return(normalVectors);
}
/// <summary>
/// Rotates this point about another by the given rotation.
/// </summary>
/// <param name="targetPoint">This <see cref="Vector2"/> instance.</param>
/// <param name="rotationPoint">The point to rotate about.</param>
/// <param name="rotation">The rotation to perform (in radians).</param>
/// <returns>The new rotated point.</returns>
public static Vector2 RotateAbout(this Vector2 targetPoint, Vector2 rotationPoint, float rotation)
{
Vector2 difference = targetPoint - rotationPoint; // Center the point of rotation at the origin
if (difference == Vector2.Zero)
{
return(targetPoint);
}
else
{
float angle = difference.AngleBetween(Vector2Helper.Up) + rotation; // Get the new angle from the UP vector
return((Vector2Helper.VectorFromRotation(angle) * difference.Length()) + rotationPoint); // Get the new vector and move it off the origin
}
}