ColliderRegistry.cs

namespace Gondwana.Physics.Collisions;

public sealed class ColliderRegistry
{
    internal Gondwana.Scenes.SceneLayer? SceneLayer { get; set; }

    public void QueryInstances(in Aabb area, int layerMask, int collidesWithMask,
        List<ColliderInstance> results, ICollider? ignore = null)
    {
        results.Clear();
        var layer = SceneLayer;
        var periodic = layer is not null && (layer.WrapHorizontally || layer.WrapVertically);
        var period = periodic ? layer!.GetPeriod() : default;
        var query = new System.Drawing.RectangleF(area.MinX, area.MinY, area.Width, area.Height);
        foreach (var collider in _static.Concat(_dynamic))
        {
            if (ReferenceEquals(collider, ignore) || (collider.CollisionGroup & collidesWithMask) == 0 || (layerMask & collider.CollidesWith) == 0)
                continue;
            var bounds = collider.BoundsWorldPx;
            if (!periodic)
            {
                if (area.Intersects(bounds)) results.Add(new(collider, bounds));
                continue;
            }
            foreach (var offset in period.Offsets(new(bounds.MinX, bounds.MinY, bounds.Width, bounds.Height), query))
                results.Add(new(collider, new(bounds.MinX + offset.X, bounds.MinY + offset.Y, bounds.MaxX + offset.X, bounds.MaxY + offset.Y)));
        }
    }
 
    private readonly HashSet<ICollider> _static = new();
    private readonly HashSet<ICollider> _dynamic = new();

    public IEnumerable<ICollider> StaticColliders => _static;

    public IEnumerable<ICollider> DynamicColliders => _dynamic;

    public void Register(ICollider collider)
    {
        if (collider is null)
            throw new ArgumentNullException(nameof(collider));
 
        if (collider.IsStatic)
            _static.Add(collider);
        else
            _dynamic.Add(collider);
    }

    public void Unregister(ICollider collider)
    {
        if (collider is null)
            return;
 
        if (collider.IsStatic)
            _static.Remove(collider);
        else
            _dynamic.Remove(collider);
    }

    public void QueryAabb(
        in Aabb area,
        int layerMask,
        int collidesWithMask,
        List<ICollider> results,
        ICollider? ignore = null)
    {
        var instances = new List<ColliderInstance>();
        QueryInstances(area, layerMask, collidesWithMask, instances, ignore);
        results.Clear();
        foreach (var instance in instances)
            if (!results.Contains(instance.Collider)) results.Add(instance.Collider);
    }
}