Question

I’m making a simple game in XNA (for Windows, if that makes a difference), and when the player moves right, I’m using the following code to rotate the ship model to make it look like the ship is leaning into the strafe:

RotationMatrix = Matrix.CreateRotationX(MathHelper.PiOver2) *
                 Matrix.CreateRotationY(0.4f);

That works, but it instantly pops the ship to the desired rotation. I would rather it ease in over a few frames. For reference, the rotation matrix was declared as follows:

public Matrix RotationMatrix = Matrix.CreateRotationX(MathHelper.PiOver2);

What can I do to smooth the lean?

Answer 1

I think that You just need to include time into your code. In Xna, you have access to GameTime object (in Game.Draw method, for example ), so, you may try something like this:

private float _seconds = 0;
protected override void Draw(GameTime gameTime)
{
    if (_seconds < 1)
    {
        _seconds += gameTime.ElapsedGameTime.TotalSeconds;
    }
    RotationMatrix = Matrix.CreateRotationX(MathHelper.PiOver2) *
         Matrix.CreateRotationY(0.4f * _seconds);
    base.Draw(gameTime);
}

From place I’m now, I cannot check if this code is valid, so this is only idea ;).