rhythmbullet/RhythmBullet/Zer01HD/Utilities/Camera/Camera2D.cs

using Microsoft.Xna.Framework;
using Microsoft.Xna.Framework.Graphics;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace RhythmBullet.Zer01HD.Utilities.Camera
{
    public class Camera2D
    {
        public float Zoom;
        public Vector2 Position;
        public Matrix TransformMatrix { get; private set; }
        public GraphicsDevice graphicsDevice;

        public Camera2D(GraphicsDevice graphicsDevice)
        {
            this.graphicsDevice = graphicsDevice;
            Zoom = 1f;
            Position.X = this.graphicsDevice.Viewport.Width * 0.5f;
            Position.Y = this.graphicsDevice.Viewport.Height * 0.5f;
        }

        public void Update()
        {
            Rectangle bounds = graphicsDevice.Viewport.Bounds;
            TransformMatrix = 
                Matrix.CreateTranslation(new Vector3(-Position.X, -Position.Y, 0)) * 
                Matrix.CreateScale(Zoom) * 
                Matrix.CreateTranslation(new Vector3(bounds.Width * 0.5f, bounds.Height * 0.5f, 0f));
        }

        public void LinearInterpolationToPosition(float alpha, Vector2 targetPosition, float delta)
        {
            if (alpha <= 0 && alpha > 1f) throw new ArgumentException("Alpha can't be greater than 1f, less than or equal to 0.");

            Vector2 distance = targetPosition - Position;
            distance *= (float)(1.0f - Math.Pow(1 - alpha, delta / 0.02f));

            Position += distance;
        }
    }
}