Engine-Pong/Game/Behaviours/MonoGameCamera2DBehaviour.cs

using Microsoft.Xna.Framework;
using Microsoft.Xna.Framework.Graphics;

using Syntriax.Engine.Core;
using Syntriax.Engine.Core.Abstract;

namespace Pong.Behaviours;

public class MonoGameCamera2DBehaviour(GraphicsDeviceManager Graphics) : BehaviourOverride, ICamera2D
{
    public event OnMatrixTransformChangedDelegate? OnMatrixTransformChanged = null;
    public event OnViewportChangedDelegate? OnViewportChanged = null;
    public event OnZoomChangedDelegate? OnZoomChanged = null;

    private Matrix _matrixTransform = Matrix.Identity;

    private Viewport _viewport = default;
    private float _zoom = 1f;

    public GraphicsDeviceManager Graphics { get; } = Graphics;

    public Matrix MatrixTransform
    {
        get => _matrixTransform;
        set
        {
            if (_matrixTransform == value)
                return;

            _matrixTransform = value;
            OnMatrixTransformChanged?.Invoke(this);
        }
    }

    public Vector2D Position
    {
        get => Transform.Position;
        set => Transform.Position = value;
    }

    public Viewport Viewport
    {
        get => _viewport;
        set
        {
            if (_viewport.Equals(value))
                return;

            _viewport = value;
            OnViewportChanged?.Invoke(this);
        }
    }

    public float Zoom
    {
        get => _zoom;
        set
        {
            float newValue = Math.Max(0.1f, value);

            if (_zoom == newValue)
                return;

            _zoom = newValue;
            OnZoomChanged?.Invoke(this);
        }
    }

    public float Rotation
    {
        get => Transform.Rotation;
        set => Transform.Rotation = value;
    }

    public event IAssignableTransform.OnTransformAssignedDelegate? OnTransformAssigned { add => GameObject.OnTransformAssigned += value; remove => GameObject.OnTransformAssigned -= value; }
    ITransform IAssignableTransform.Transform => GameObject.Transform;
    bool IAssignableTransform.Assign(ITransform transform) => GameObject.Assign(transform);

    // TODO This causes delay since OnPreDraw calls assuming this is called in in Update 
    public Vector2D ScreenToWorldPosition(Vector2D screenPosition)
    {
        Vector2D worldPosition = Vector2.Transform(screenPosition.ToVector2(), Matrix.Invert(MatrixTransform)).ToVector2D();
        return worldPosition.Scale(EngineConverter.screenScale);
    }
    public Vector2D WorldToScreenPosition(Vector2D worldPosition)
    {
        Vector2D screenPosition = Vector2.Transform(worldPosition.ToVector2(), MatrixTransform).ToVector2D();
        return screenPosition.Scale(EngineConverter.screenScale);
    }

    protected override void OnFirstActiveFrame()
        => Viewport = Graphics.GraphicsDevice.Viewport;

    protected override void OnPreDraw()
    {
        MatrixTransform =
            Matrix.CreateTranslation(new Vector3(-Position.X, Position.Y, 0f)) *
            Matrix.CreateRotationZ(Rotation * Math.DegreeToRadian) *
            Matrix.CreateScale(Zoom) *
            Matrix.CreateTranslation(new Vector3(_viewport.Width * .5f, _viewport.Height * .5f, 0f));
    }

    public delegate void OnMatrixTransformChangedDelegate(MonoGameCamera2DBehaviour sender);
    public delegate void OnViewportChangedDelegate(MonoGameCamera2DBehaviour sender);
    public delegate void OnZoomChangedDelegate(MonoGameCamera2DBehaviour sender);
}