Voile/DaggerFramework/Source/SceneGraph/EntityLayer.cs

using DaggerFramework.Rendering;
using DaggerFramework.Utils;

namespace DaggerFramework.SceneGraph
{
    public class EntityLayer : Layer
    {
        public List<Entity> Entities { get => _entities; }
        public Camera2d CurrentCamera { get; set; }

        public EntityLayer(List<Entity> entities)
        {
            _entities = entities;
        }

        public EntityLayer()
        {
            _entities = new List<Entity>();
        }

        public void UpdateCurrentCamera()
        {
            if (_cameraEntities.Count == 1)
            {
                CurrentCamera = _cameraEntities[0];
                return;
            }
            else
            {
                foreach (var camera in _cameraEntities)
                {
                    if (camera.Current) CurrentCamera = camera;
                }
            }
        }

        public bool AddEntity(Entity entity)
        {
            entity.Id = Entities.Count;
            entity.Layer = this;

            if (entity is Camera2d camera2d)
            {
                _cameraEntities.Add(camera2d);
                UpdateCurrentCamera();
            }

            Entities.Add(entity);


            return true;
        }

        public void DestroyEntity(int at)
        {
            _entities.RemoveAt(at);
        }

        protected override void OnStart()
        {
            for (int i = 0; i < _entities.Count; i++)
            {
                var entity = _entities[i];
                entity.Layer = this;
                entity.Start();
            }
        }

        protected override void OnUpdate(double dt)
        {
            foreach (var entity in _entities)
            {
                entity.Update(dt);
            }
        }

        protected override void OnBeginDraw(Renderer renderer)
        {
            var hasCamera = CurrentCamera != null;
            if (hasCamera)
            {
                renderer.BeginCamera2d(CurrentCamera.Offset, CurrentCamera.Position, 0f, CurrentCamera.Zoom);
            }
        }

        protected override void OnEndDraw(Renderer renderer)
        {
            var hasCamera = CurrentCamera != null;
            if (hasCamera)
            {
                renderer.EndCamera2d();
            }
        }


        protected override void OnDraw(Renderer renderer)
        {
            // TODO: can be done more efficiently, needs rendering redesign.
            foreach (var entity in _entities)
            {
                if (entity is IDrawable drawable)
                {
                    drawable.Draw(renderer);
                }
            }
        }

        private List<Entity> _entities;
        private List<Camera2d> _cameraEntities = new();
    }
}