riversong-code-showcase/Source/Riversong/Game/World/Agents/Critters/CritterSpawnSystem.cs

using Unity.Mathematics;
using UnityEngine;
using UnityEngine.Pool;
using Random = UnityEngine.Random;

namespace DanieleMarotta.RiversongCodeShowcase
{
    [GameSystemGroup(typeof(EarlyAgentsSystemGroup))]
    public class CritterSpawnSystem : GameSystem, IUpdatable
    {
        [InjectService]
        private World _world;

        [InjectService]
        private IEntityCollection _entityCollection;

        [InjectService]
        private IAgentFactory _agentFactory;

        [InjectService]
        private ITileSpace _tileSpace;

        public CritterSpawnSystem(IServiceLocator serviceLocator) : base(serviceLocator)
        {
        }

        public void Update()
        {
            foreach (CritterHerd herd in _entityCollection.GetInternalEntityList(typeof(CritterHerd)))
            {
                ref var agentSourceState = ref herd.GetAgentSourceStateRW();

                if (agentSourceState.AgentCount[(int)AgentJob.None] >= herd.MaxCritterCount)
                {
                    herd.SpawnTimer = float.MinValue;
                    continue;
                }

                var critterDefinition = herd.CritterDefinition;

                if (herd.SpawnTimer < 0) herd.SpawnTimer = Random.Range(critterDefinition.MinSpawningInterval, critterDefinition.MaxSpawningInterval);

                herd.SpawnTimer -= Time.deltaTime;
                if (herd.SpawnTimer <= 0)
                {
                    herd.SpawnTimer = float.MinValue;

                    var wanderingRadius = critterDefinition.AgentDefinition.WanderingRadius;
                    if (!TryFindRandomFreeTile(herd.Center - wanderingRadius, herd.Center + wanderingRadius, out var tile)) continue;

                    var position = _tileSpace.TileToWorld(tile);
                    var critter = _agentFactory.CreateCritter(critterDefinition, herd, position);
                    critter.WanderingCenter = tile;

                    ref var intentQueue = ref critter.GetIntentQueueRW();
                    intentQueue.EnqueueIntent(AgentIntent.MakeLive());
                    IntentQueue.LoopWandering(ref intentQueue, 0);
                }
            }
        }

        private bool TryFindRandomFreeTile(int2 min, int2 max, out int2 tile)
        {
            using var candidatesScope = ListPool<int2>.Get(out var candidates);

            foreach (var candidate in TileRange.From(min, max))
                if (!_world.BlockMap.IsBlocked(candidate, BlockReason.BlocksAgents))
                    candidates.Add(candidate);

            if (candidates.Count == 0)
            {
                tile = int2.zero;
                return false;
            }

            tile = candidates[Random.Range(0, candidates.Count)];
            return true;
        }
    }
}