92 lines
2.6 KiB
C#
92 lines
2.6 KiB
C#
namespace SpaceGame.Simulation.Api.Simulation;
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public abstract class GoapAction<TState>
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{
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public abstract string Name { get; }
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public abstract float Cost { get; }
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public abstract bool CheckPreconditions(TState state);
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public abstract TState ApplyEffects(TState state);
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public abstract void Execute(SimulationEngine engine, SimulationWorld world, CommanderRuntime commander);
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}
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public abstract class GoapGoal<TState>
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{
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public abstract string Name { get; }
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public abstract bool IsSatisfied(TState state);
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public abstract float ComputePriority(TState state, SimulationWorld world, CommanderRuntime commander);
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}
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public sealed class GoapPlan<TState>
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{
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public static readonly GoapPlan<TState> Empty = new() { Actions = [], TotalCost = 0f };
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public required IReadOnlyList<GoapAction<TState>> Actions { get; init; }
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public required float TotalCost { get; init; }
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public int CurrentStep { get; set; }
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public GoapAction<TState>? CurrentAction => CurrentStep < Actions.Count ? Actions[CurrentStep] : null;
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public bool IsComplete => CurrentStep >= Actions.Count;
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public void Advance() => CurrentStep++;
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}
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public sealed class GoapPlanner<TState>
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{
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private readonly Func<TState, TState> cloneState;
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public GoapPlanner(Func<TState, TState> cloneState)
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{
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this.cloneState = cloneState;
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}
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public GoapPlan<TState>? Plan(
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TState initialState,
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GoapGoal<TState> goal,
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IReadOnlyList<GoapAction<TState>> availableActions)
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{
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if (goal.IsSatisfied(initialState))
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{
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return GoapPlan<TState>.Empty;
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}
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var openSet = new PriorityQueue<PlanNode, float>();
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openSet.Enqueue(new PlanNode(cloneState(initialState), [], 0f), 0f);
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const int MaxIterations = 256;
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var iterations = 0;
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while (openSet.Count > 0 && iterations++ < MaxIterations)
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{
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var current = openSet.Dequeue();
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if (goal.IsSatisfied(current.State))
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{
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return new GoapPlan<TState>
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{
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Actions = current.Actions,
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TotalCost = current.Cost,
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};
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}
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foreach (var action in availableActions)
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{
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if (!action.CheckPreconditions(current.State))
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{
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continue;
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}
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var newState = action.ApplyEffects(cloneState(current.State));
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var newCost = current.Cost + action.Cost;
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var newActions = new List<GoapAction<TState>>(current.Actions) { action };
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openSet.Enqueue(new PlanNode(newState, newActions, newCost), newCost);
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}
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}
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return null;
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}
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private sealed record PlanNode(
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TState State,
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IReadOnlyList<GoapAction<TState>> Actions,
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float Cost);
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}
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