sandpypi/Sand.ChunkPrototype/PrototypeSparseSandAdapter.Runtime.Reactions.cs

using Sand.Core;

namespace Sand.ChunkPrototype;

public sealed partial class PrototypeSparseSandAdapter
{
    private bool ApplyLocalReaction(int x, int y, PrototypeParticle particle, ref int seed)
    {
        Span<(int X, int Y)> neighbors = [(x - 1, y), (x + 1, y), (x, y - 1), (x, y + 1)];
        for (var i = 0; i < neighbors.Length; i++)
        {
            var (nx, ny) = neighbors[i];
            if (!TryGetParticle(nx, ny, out var neighbor))
            {
                continue;
            }

            if (particle.HasFlag(PrototypeParticleFlags.WaterLike) && neighbor.HydrateTargetTypeId != 0 && TryResolveProfile(neighbor.HydrateTargetTypeId, out var hydrated))
            {
                ReplaceParticle(nx, ny, hydrated);
                RemoveParticle(x, y);
                return true;
            }

            if (particle.HasFlag(PrototypeParticleFlags.FireLike) && neighbor.HasFlag(PrototypeParticleFlags.WaterLike))
            {
                RemoveParticle(x, y);
                if (neighbor.EvaporateTypeId != 0 && TryResolveProfile(neighbor.EvaporateTypeId, out var steam))
                {
                    ReplaceParticle(nx, ny, steam);
                }

                return true;
            }

            if (particle.HasFlag(PrototypeParticleFlags.HotSource) && neighbor.HasFlag(PrototypeParticleFlags.WaterLike))
            {
                if (particle.SolidifyTypeId != 0 && TryResolveProfile(particle.SolidifyTypeId, out var solidifiedSelf))
                {
                    ReplaceParticle(x, y, solidifiedSelf);
                }

                if (neighbor.EvaporateTypeId != 0 && TryResolveProfile(neighbor.EvaporateTypeId, out var vaporizedNeighbor))
                {
                    ReplaceParticle(nx, ny, vaporizedNeighbor);
                }
                else
                {
                    RemoveParticle(nx, ny);
                }

                return true;
            }

            if (particle.HasFlag(PrototypeParticleFlags.Acidic) &&
                !neighbor.IsStatic &&
                !neighbor.HasFlag(PrototypeParticleFlags.Acidic) &&
                NextChance(ref seed) <= 0.08f)
            {
                RemoveParticle(nx, ny);
                if (NextChance(ref seed) <= 0.18f)
                {
                    RemoveParticle(x, y);
                    return true;
                }
            }
        }

        return false;
    }

    private void ApplyPhaseTransition(int x, int y, ref PrototypeParticle particle)
    {
        var localTemperature = GetTemperatureAt(x, y);
        var localPressure = GetPressureLoad(x, y);
        var fieldForce = GetFieldForceMagnitude(x, y);
        if (fieldForce > 0f)
        {
            localPressure += fieldForce * 0.2f;
        }

        var cellAge = GetCellAgeAt(x, y);
        if (particle.PhaseTransitionHysteresis > 0f && cellAge < particle.PhaseTransitionHysteresis)
        {
            return;
        }

        if (particle.EvaporateTypeId != 0 &&
            localTemperature >= particle.EvaporateTemperature &&
            TryResolveProfile(particle.EvaporateTypeId, out var evaporated))
        {
            ReplaceParticle(x, y, evaporated);
            particle = evaporated;
            return;
        }

        if (particle.MeltTypeId != 0 &&
            localTemperature >= particle.MeltTemperature &&
            TryResolveProfile(particle.MeltTypeId, out var melted))
        {
            ReplaceParticle(x, y, melted);
            particle = melted;
            return;
        }

        if (particle.FreezeTypeId != 0 &&
            localTemperature <= particle.FreezeTemperature &&
            TryResolveProfile(particle.FreezeTypeId, out var frozen))
        {
            ReplaceParticle(x, y, frozen);
            particle = frozen;
            return;
        }

        if (particle.SolidifyTypeId != 0 &&
            (localTemperature <= particle.SolidifyTemperature ||
             (particle.MotionType == PrototypeParticleType.Steam && localPressure >= MathF.Max(0.9f, particle.PressureThreshold * 0.35f))) &&
            TryResolveProfile(particle.SolidifyTypeId, out var condensed))
        {
            ReplaceParticle(x, y, condensed);
            if (TryGetCellPage(x, y, out _, out var page, out var localX, out var localY))
            {
                page.SetTemperature(localX, localY, MathF.Max(condensed.InitialTemperature, MathF.Min(localTemperature, 95f)));
            }

            particle = condensed;
        }
    }

    private float GetCellAgeAt(int x, int y)
    {
        if (!TryGetCellPage(x, y, out _, out var page, out var localX, out var localY))
        {
            return 0f;
        }

        return page.GetCellAge(localX, localY);
    }

    private bool HasPotentialReactiveNeighbor(int x, int y, PrototypeParticle particle)
    {
        Span<(int X, int Y)> neighbors = [(x - 1, y), (x + 1, y), (x, y - 1), (x, y + 1)];
        for (var i = 0; i < neighbors.Length; i++)
        {
            var (nx, ny) = neighbors[i];
            if (!TryGetParticle(nx, ny, out var neighbor))
            {
                continue;
            }

            if (particle.HasFlag(PrototypeParticleFlags.WaterLike) && neighbor.HydrateTargetTypeId != 0)
            {
                return true;
            }

            if (particle.HydrateTargetTypeId != 0 && neighbor.HasFlag(PrototypeParticleFlags.WaterLike))
            {
                return true;
            }

            if ((particle.HasFlag(PrototypeParticleFlags.FireLike) || particle.HasFlag(PrototypeParticleFlags.HotSource)) && neighbor.HasFlag(PrototypeParticleFlags.WaterLike))
            {
                return true;
            }

            if (particle.HasFlag(PrototypeParticleFlags.Acidic) && !neighbor.IsStatic && !neighbor.HasFlag(PrototypeParticleFlags.Acidic))
            {
                return true;
            }
        }

        return false;
    }
}