SFPM.Flecs (Using Flecs.Net to query data from)

Instead of creating our own query system and handling key value stores, we will be using entities and components instead.

Why?

One problem we have is, the payload of rules should be able to write data back, something like event_x_happened = true, so we need to implicity pass the database/key-value-store to the payload. But how would you keep the data from the database/key-value-store in sync from its source?

What do I mean with that?

Imagine we have various npc objects there data is stored in their fields not in a database/key-value-store so we would have to mirror them instead. We could store a refrence but I feel there is something missing. A flat storage like its found in a ECS world would be much better to handle, as we can simply pass an ECS-World implicitly. And changing in it are reflected correctly and are kept in sync with systems that are running. Also we could create a query system that runs over rules that are defined as components for entities.

ECS World Extensions

Extension methods for integrating SFPM (Stella Fuzzy Pattern Matcher) rules with Flecs.NET Entity Component System.

Basic Usage

There are two main ways to define rules in your ECS world:

1. Rules as Entities

// Create world and entities World world = World.Create(); var player = world.Entity() .Set<Name>(new(Value: "Nick")) .Set<Health>(new(Value: 100)); // Create a rule entity with NPC tag var rule = world.Entity() .Set<NPC, Rule>(new Rule(criterias: [ new Criteria<Name>("who", who => who.Value == "Nick"), new Criteria<string>("concept", concept => concept == "onHit"), new Criteria<Map>("curMap", map => map.Name == "circus") ], payload: () => { // Rule actions here })); // Match rules against query data var queryData = new Dictionary<string, object> { { "concept", "onHit" }, { "who", player.Get<Name>() }, // Get component data from entity { "curMap", world.Get<Map>() } // Get singleton component }; world.MatchOnEntities<NPC>(queryData);

2. Rules as World Component

// Set rules as a world-level component world.Set<NPC, List<Rule>>(new List<Rule> { new Rule(criterias: [ new Criteria<string>("who", who => who == "Nick"), new Criteria<string>("concept", concept => concept == "onHit"), new Criteria<int>("nearAllies", allies => allies > 1) ], payload: () => { // Rule actions here }) }); // Match world-level rules world.MatchOnWorld<NPC>(queryData);

Performance Optimization

Rules can be optimized to evaluate more specific rules first:

// Optimize entity-based rules world.OptimizeWorldRules(); // Optimize tagged rules world.OptimizeWorldRules<NPC>();

Rule Evaluation Process

The matching process:

1. Rules are evaluated against provided query data
2. Rules with most matched criteria get priority
3. Among equally matched rules:
   • Grouped by priority
   • Random selection from highest priority group
4. Selected rule's payload is executed

Tips

• Use MatchOnEntities<T> for rules stored as components on entities
• Use MatchOnWorld<T> for rules stored as world-level components
• Rules can access and modify ECS components in their payloads
• Component data in query can come from entities or world singletons

This extension integrates SFPM's rule system with Flecs.NET's ECS architecture for dynamic, data-driven behavior systems.