Crude swap+pop container

StructArray.cs

    // Swap to pop array of structs
    public class StructArray<T> where T : struct
    {
        public T[] items_;
        public int Count { get; private set; }
        public int Capacity { get; private set; }

        public StructArray(int capacity)
        {
            Resize(capacity);
            Count = 0;
        }

        public void Resize(int newSize)
        {
            Array.Resize(ref items_, newSize);
            Capacity = newSize;
        }

        public int GetNextIndex()
        {
            if (Count == Capacity)
                return -1;
            ++Count;
            return Count - 1;
        }

        public void Remove(int idx)
        {
            if (idx == -1)
                return;

            items_[idx] = items_[Count - 1];
            --Count;
        }
    }