feat(ai): add wander AI system with move boost

Add AIBase and WanderAITag components, a WanderAISystem, and a MoveBoost component to control wandering behavior. Replace the old MoveState with MoveBoost and include a horizontal random direction helper.

include/Cubed/gameplay/ecs/ai_struct.hpp

@@ -0,0 +1,17 @@
+#pragma once
+
+#include "Cubed/gameplay/game_time.hpp"
+namespace Cubed {
+struct AIBase {
+    TickType interval = 1;
+    TickType count = 0;
+};
+
+struct WanderAITag {};
+
+struct MoveBoost {
+    TickType duration = 0;
+    TickType count = 0;
+};
+
+} // namespace Cubed

include/Cubed/gameplay/ecs/server_entity.hpp

@@ -1,7 +1,6 @@
 #pragma once
 #include "Cubed/gameplay/ecs/health.hpp"
 #include "Cubed/gameplay/ecs/movement.hpp"
-#include "Cubed/gameplay/ecs/state.hpp"
 #include "Cubed/gameplay/ecs/transform.hpp"
 #include "Cubed/gameplay/hitbox.hpp"
 namespace Cubed {
@@ -13,8 +12,6 @@ struct BaseServerCreature {
 
     Movement movement{};
 
-    MoveState move_state{};
-
     Direction direction{};
 
     Gravity gravity{};

include/Cubed/gameplay/systems/wander_ai_system.hpp

@@ -0,0 +1,14 @@
+#pragma once
+#include "Cubed/gameplay/ecs/ai_struct.hpp"
+#include "Cubed/gameplay/ecs/server_entity.hpp"
+
+#include <entt/entt.hpp>
+namespace Cubed {
+class WanderAISystem {
+public:
+    static void update(entt::registry& registry);
+
+private:
+    static void do_ai(BaseServerCreature& creature, MoveBoost& move_boost);
+};
+} // namespace Cubed

include/Cubed/tools/cubed_random.hpp

@@ -1,4 +1,6 @@
 #pragma once
+#include "glm/ext/vector_float3.hpp"
+
 #include <random>
 namespace Cubed {
 
@@ -14,6 +16,8 @@ public:
     int random_int(int min, int max);
     float random_float(float min, float max);
 
+    glm::vec3 random_direction_horizontal();
+
 private:
     unsigned int m_seed = 0;
     std::mt19937 m_engine;

src/CMakeLists.txt

@@ -102,4 +102,5 @@ target_sources(${PROJECT_NAME}
         gameplay/client_player_manager.cpp
         gameplay/server_entity_manager.cpp
         gameplay/client_entity_manager.cpp
+        gameplay/systems/wander_ai_system.cpp
 )

src/gameplay/systems/wander_ai_system.cpp

@@ -0,0 +1,40 @@
+#include "Cubed/gameplay/systems/wander_ai_system.hpp"
+
+#include "Cubed/gameplay/ecs/ai_struct.hpp"
+#include "Cubed/gameplay/ecs/server_entity.hpp"
+#include "Cubed/tools/cubed_random.hpp"
+
+namespace {
+constexpr double DIRECTION_PROBABILITY = 0.1;
+constexpr double MOVE_PROBABILITY = 0.1;
+} // namespace
+
+namespace Cubed {
+void WanderAISystem::update(entt::registry& registry) {
+    auto view =
+        registry.view<AIBase, WanderAITag, BaseServerCreature, MoveBoost>();
+
+    for (auto e : view) {
+        auto [ai, creature, move_boost] =
+            view.get<AIBase, BaseServerCreature, MoveBoost>(e);
+        ++ai.count;
+        if (ai.count >= ai.interval) {
+            ai.count = 0;
+            do_ai(creature, move_boost);
+        }
+    }
+}
+
+void WanderAISystem::do_ai(BaseServerCreature& creature,
+                           MoveBoost& move_boost) {
+    thread_local Random r{std::random_device()()};
+    if (r.random_bool(DIRECTION_PROBABILITY)) {
+        creature.direction.value = r.random_direction_horizontal();
+    }
+    if (r.random_bool(MOVE_PROBABILITY)) {
+        move_boost.duration = r.random_int(5, 8);
+        move_boost.count = 0;
+    }
+}
+
+} // namespace Cubed

src/tools/cubed_random.cpp

@@ -1,8 +1,11 @@
 #include "Cubed/tools/cubed_random.hpp"
 
+#include <cmath>
+#include <numbers>
 namespace Cubed {
 
 Random::Random() {}
+
 Random::Random(unsigned seed) { init(seed); }
 bool Random::random_bool(double probability) {
     if (probability <= 0.0)
@@ -44,4 +47,12 @@ float Random::random_float(float min, float max) {
 
     return result;
 }
+
+glm::vec3 Random::random_direction_horizontal() {
+    float x = std::cos(random_float(0.0f, 2 * std::numbers::pi));
+    float z = std::sin(random_float(0.0f, 2 * std::numbers::pi));
+
+    return glm::vec3{x, 0.0f, z};
+}
+
 } // namespace Cubed