9 files changed, 258 insertions, 1 deletions

diff --git a/src/crepe/api/AI.cpp b/src/crepe/api/AI.cpp
new file mode 100644
index 0000000..7f820a8
--- /dev/null
+++ b/src/crepe/api/AI.cpp
@@ -0,0 +1,11 @@
+#include "AI.h"
+
+namespace crepe {
+
+AI::AI(game_object_id_t id, float mass, float max_speed, float max_force)
+	: Component(id),
+	  mass(mass),
+	  max_speed(max_speed),
+	  max_force(max_force) {}
+
+} // namespace crepe
diff --git a/src/crepe/api/AI.h b/src/crepe/api/AI.h
new file mode 100644
index 0000000..242ff89
--- /dev/null
+++ b/src/crepe/api/AI.h
@@ -0,0 +1,60 @@
+#pragma once
+
+#include "Component.h"
+#include "types.h"
+
+namespace crepe {
+
+class AI : public Component {
+public:
+	enum BehaviorType {
+		NONE = 0x00000,
+		SEEK = 0x00002,
+		FLEE = 0x00004,
+		ARRIVE = 0x00008,
+		PATH_FOLLOW = 0x00010,
+	};
+
+public:
+	AI(game_object_id_t id, float mass, float max_speed, float max_force);
+
+	bool on(BehaviorType behavior) const { return (flags & behavior) == behavior; }
+	void seek_on() { flags |= SEEK; }
+	void seek_off() {
+		if (on(SEEK)) flags ^= SEEK;
+	}
+	void flee_on() { flags |= FLEE; }
+	void flee_off() {
+		if (on(FLEE)) flags ^= FLEE;
+	}
+	void arrive_on() { flags |= ARRIVE; }
+	void arrive_off() {
+		if (on(ARRIVE)) flags ^= ARRIVE;
+	}
+	void path_follow_on() { flags |= PATH_FOLLOW; }
+	void path_follow_off() {
+		if (on(PATH_FOLLOW)) flags ^= PATH_FOLLOW;
+	}
+
+public:
+	float mass;
+	float max_speed;
+	float max_force;
+
+	// The target to seek or arrive at
+	vec2 seek_target;
+	// The target to flee from
+	vec2 flee_target;
+	// The distance at which the entity will start to flee from the target
+	float square_flee_panic_distance = 100.0f * 100.0f;
+	// The deceleration rate for the arrive behavior (higher values will make the entity decelerate faster (less overshoot))
+	float arrive_deceleration = 2.0f;
+
+private:
+	vec2 velocity;
+	friend class AISystem;
+
+	int flags = 0;
+};
+
+} // namespace crepe
diff --git a/src/crepe/api/CMakeLists.txt b/src/crepe/api/CMakeLists.txt
index ac8f301..0355b72 100644
--- a/src/crepe/api/CMakeLists.txt
+++ b/src/crepe/api/CMakeLists.txt
@@ -22,6 +22,7 @@ target_sources(crepe PUBLIC
 	Script.cpp
 	Button.cpp
 	UIObject.cpp
+	AI.cpp
 )
 
 target_sources(crepe PUBLIC FILE_SET HEADERS FILES
@@ -54,4 +55,5 @@ target_sources(crepe PUBLIC FILE_SET HEADERS FILES
 	Asset.h
 	Button.h
 	UIObject.h
+	AI.h
 )
diff --git a/src/crepe/api/LoopManager.cpp b/src/crepe/api/LoopManager.cpp
index dc2d9e0..e4b1609 100644
--- a/src/crepe/api/LoopManager.cpp
+++ b/src/crepe/api/LoopManager.cpp
@@ -1,3 +1,5 @@
+#include "../facade/SDLContext.h"
+#include "../system/AISystem.h"
 #include "../system/AnimatorSystem.h"
 #include "../system/CollisionSystem.h"
 #include "../system/InputSystem.h"
@@ -22,6 +24,7 @@ LoopManager::LoopManager() {
 	this->load_system<RenderSystem>();
 	this->load_system<ScriptSystem>();
 	this->load_system<InputSystem>();
+	this->load_system<AISystem>();
 }
 
 void LoopManager::process_input() { this->get_system<InputSystem>().update(); }
@@ -51,6 +54,11 @@ void LoopManager::loop() {
 		this->render();
 
 		timer.enforce_frame_rate();
+
+		// Stop the game after 10 seconds, for testing purposes
+		if (timer.get_current_time() > 10) {
+			this->game_running = false;
+		}
 	}
 }
 
@@ -60,6 +68,7 @@ void LoopManager::setup() {
 	this->game_running = true;
 	timer.start();
 	timer.set_fps(200);
+	this->scene_manager.load_next_scene();
 }
 
 void LoopManager::render() {
@@ -68,4 +77,7 @@ void LoopManager::render() {
 	this->get_system<RenderSystem>().update();
 }
 
-void LoopManager::update() {}
+void LoopManager::update() {
+	this->get_system<AnimatorSystem>().update();
+	this->get_system<AISystem>().update();
+}
diff --git a/src/crepe/api/Vector2.h b/src/crepe/api/Vector2.h
index c278c87..bbcb932 100644
--- a/src/crepe/api/Vector2.h
+++ b/src/crepe/api/Vector2.h
@@ -66,6 +66,30 @@ struct Vector2 {
 
 	//! Checks if this vector is not equal to another vector.
 	bool operator!=(const Vector2<T> & other) const;
+
+	//! Truncates the vector to a maximum length.
+	void truncate(T max);
+
+	//! Normalizes the vector.
+	void normalize();
+
+	//! Returns the length of the vector.
+	T length() const;
+
+	//! Returns the squared length of the vector.
+	T length_squared() const;
+
+	//! Returns the dot product of this vector and another vector.
+	T dot(const Vector2<T> & other) const;
+
+	//! Returns the distance between this vector and another vector.
+	T distance(const Vector2<T> & other) const;
+
+	//! Returns the squared distance between this vector and another vector.
+	T distance_squared(const Vector2<T> & other) const;
+
+	//! Returns the perpendicular vector to this vector.
+	Vector2 perpendicular() const;
 };
 
 } // namespace crepe
diff --git a/src/crepe/api/Vector2.hpp b/src/crepe/api/Vector2.hpp
index cad15f8..ff53cb0 100644
--- a/src/crepe/api/Vector2.hpp
+++ b/src/crepe/api/Vector2.hpp
@@ -1,5 +1,7 @@
 #pragma once
 
+#include <cmath>
+
 #include "Vector2.h"
 
 namespace crepe {
@@ -115,4 +117,50 @@ bool Vector2<T>::operator!=(const Vector2<T> & other) const {
 	return !(*this == other);
 }
 
+template <class T>
+void Vector2<T>::truncate(T max) {
+	if (length() > max) {
+		normalize();
+		*this *= max;
+	}
+}
+
+template <class T>
+void Vector2<T>::normalize() {
+	T len = length();
+	if (len > 0) {
+		*this /= len;
+	}
+}
+
+template <class T>
+T Vector2<T>::length() const {
+	return std::sqrt(x * x + y * y);
+}
+
+template <class T>
+T Vector2<T>::length_squared() const {
+	return x * x + y * y;
+}
+
+template <class T>
+T Vector2<T>::dot(const Vector2<T> & other) const {
+	return x * other.x + y * other.y;
+}
+
+template <class T>
+T Vector2<T>::distance(const Vector2<T> & other) const {
+	return (*this - other).length();
+}
+
+template <class T>
+T Vector2<T>::distance_squared(const Vector2<T> & other) const {
+	return (*this - other).length_squared();
+}
+
+template <class T>
+Vector2<T> Vector2<T>::perpendicular() const {
+	return {-y, x};
+}
+
 } // namespace crepe
diff --git a/src/crepe/system/AISystem.cpp b/src/crepe/system/AISystem.cpp
new file mode 100644
index 0000000..9029f32
--- /dev/null
+++ b/src/crepe/system/AISystem.cpp
@@ -0,0 +1,75 @@
+#include "../ComponentManager.h"
+#include "api/LoopTimer.h"
+#include "api/Transform.h"
+#include "types.h"
+
+#include "AISystem.h"
+
+using namespace crepe;
+
+void AISystem::update() {
+	ComponentManager & mgr = this->component_manager;
+	RefVector<AI> ai_components = mgr.get_components_by_type<AI>();
+
+	double dt = LoopTimer::get_instance().get_delta_time();
+
+	for (AI & ai : ai_components) {
+		vec2 force = this->calculate(ai);
+		vec2 acceleration = force / ai.mass;
+		ai.velocity += acceleration * dt;
+		ai.velocity.truncate(ai.max_speed);
+
+		// Update the position
+		RefVector<Transform> transforms
+			= mgr.get_components_by_id<Transform>(ai.game_object_id);
+		Transform & transform = transforms.front().get();
+		transform.position += ai.velocity * dt;
+	}
+}
+
+vec2 AISystem::calculate(AI & ai) {
+	vec2 force;
+
+	if (ai.on(AI::BehaviorType::SEEK)) {
+		vec2 force_to_add = this->seek(ai);
+
+		if (!this->accumulate_force(force, force_to_add)) {
+			return force;
+		}
+	}
+	if (ai.on(AI::BehaviorType::FLEE)) {
+		// Flee from the target
+	}
+	if (ai.on(AI::BehaviorType::ARRIVE)) {
+		// Arrive at the target
+	}
+	if (ai.on(AI::BehaviorType::PATH_FOLLOW)) {
+		// Follow the path
+	}
+
+	return force;
+}
+
+bool AISystem::accumulate_force(vec2 & running_total, vec2 force_to_add) {
+	double magnitude_remaining = running_total.length();
+	double magnitude_to_add = force_to_add.length();
+
+	if (magnitude_remaining + magnitude_to_add > 0) {
+		running_total += force_to_add;
+		return true;
+	}
+
+	return false;
+}
+
+vec2 AISystem::seek(const AI & ai) {
+	ComponentManager & mgr = this->component_manager;
+	RefVector<Transform> transforms = mgr.get_components_by_id<Transform>(ai.game_object_id);
+	Transform & transform = transforms.front().get();
+
+	vec2 desired_velocity = ai.seek_target - transform.position;
+	desired_velocity.normalize();
+	desired_velocity *= ai.max_speed;
+
+	return desired_velocity - ai.velocity;
+}
diff --git a/src/crepe/system/AISystem.h b/src/crepe/system/AISystem.h
new file mode 100644
index 0000000..5e94ccb
--- /dev/null
+++ b/src/crepe/system/AISystem.h
@@ -0,0 +1,23 @@
+#pragma once
+
+#include "api/AI.h"
+
+#include "System.h"
+#include "types.h"
+
+namespace crepe {
+
+class AISystem : public System {
+public:
+	using System::System;
+
+	void update() override;
+
+private:
+	vec2 calculate(AI & ai);
+	bool accumulate_force(vec2 & running_total, vec2 force_to_add);
+
+	vec2 seek(const AI & ai);
+};
+
+} // namespace crepe
diff --git a/src/crepe/system/CMakeLists.txt b/src/crepe/system/CMakeLists.txt
index 95f6e33..7de5198 100644
--- a/src/crepe/system/CMakeLists.txt
+++ b/src/crepe/system/CMakeLists.txt
@@ -7,6 +7,7 @@ target_sources(crepe PUBLIC
 	RenderSystem.cpp
 	AnimatorSystem.cpp
 	InputSystem.cpp
+	AISystem.cpp
 )
 
 target_sources(crepe PUBLIC FILE_SET HEADERS FILES
@@ -17,4 +18,5 @@ target_sources(crepe PUBLIC FILE_SET HEADERS FILES
 	RenderSystem.h
 	AnimatorSystem.h
 	InputSystem.h
+	AISystem.h
 )