Add basic entity tracking, mob spawning and syncing

internal/server/spawner.go

@@ -0,0 +1,66 @@
+package server
+
+import (
+	"math/rand"
+	"time"
+
+	"regionio/internal/registry"
+	"regionio/internal/world"
+)
+
+// StartSpawning begins the entity tick and spawn loops.
+func (s *Server) StartSpawning() {
+	go s.entityTickLoop()
+	go s.mobSpawnLoop()
+}
+
+func (s *Server) entityTickLoop() {
+	ticker := time.NewTicker(50 * time.Millisecond) // 20 TPS
+	defer ticker.Stop()
+	for range ticker.C {
+		all := s.entities.All()
+		for _, e := range all {
+			// Basic random wandering
+			e.X += (rand.Float64() - 0.5) * 0.2
+			e.Z += (rand.Float64() - 0.5) * 0.2
+			e.Yaw += float32((rand.Float64() - 0.5) * 10.0)
+		}
+	}
+}
+
+func (s *Server) mobSpawnLoop() {
+	ticker := time.NewTicker(2 * time.Second)
+	defer ticker.Stop()
+
+	pigType := registry.Index("minecraft:entity_type", "minecraft:pig")
+	zombieType := registry.Index("minecraft:entity_type", "minecraft:zombie")
+	if pigType < 0 || zombieType < 0 {
+		return
+	}
+
+	for range ticker.C {
+		all := s.entities.All()
+		if len(all) > 50 {
+			continue // limit to 50 entities
+		}
+
+		// Spawn near the spawn point (8.5, 200, 8.5)
+		x := (rand.Float64() - 0.5) * 30.0
+		z := (rand.Float64() - 0.5) * 30.0
+		
+		t := pigType
+		name := "minecraft:pig"
+		if rand.Float32() < 0.5 {
+			t = zombieType
+			name = "minecraft:zombie"
+		}
+
+		s.entities.Add(&world.Entity{
+			TypeID:   t,
+			TypeName: name,
+			X:        x + 8.5,
+			Y:        200.0, // They float for now since there's no gravity
+			Z:        z + 8.5,
+		})
+	}
+}