4 files changed, 243 insertions, 52 deletions

diff --git a/src/crepe/system/ParticleSystem.cpp b/src/crepe/system/ParticleSystem.cpp
index 397b586..4a25b47 100644
--- a/src/crepe/system/ParticleSystem.cpp
+++ b/src/crepe/system/ParticleSystem.cpp
@@ -1,62 +1,143 @@
 #include <cmath>
+#include <cstdlib>
 #include <ctime>
 
-#include "../ComponentManager.h"
-#include "../api/ParticleEmitter.h"
+#include "api/ParticleEmitter.h"
+#include "api/Transform.h"
+#include "api/Vector2.h"
 
+#include "ComponentManager.h"
 #include "ParticleSystem.h"
 
 using namespace crepe;
 
-ParticleSystem::ParticleSystem() : elapsed_time(0.0f) {}
+ParticleSystem::ParticleSystem() {}
 
 void ParticleSystem::update() {
+	// Get all emitters
 	ComponentManager & mgr = ComponentManager::get_instance();
 	std::vector<std::reference_wrapper<ParticleEmitter>> emitters
 		= mgr.get_components_by_type<ParticleEmitter>();
-	float delta_time = 0.10;
+
 	for (ParticleEmitter & emitter : emitters) {
-		float update_amount = 1 / static_cast<float>(emitter.emission_rate);
-		for (float i = 0; i < delta_time; i += update_amount) {
-			emit_particle(emitter);
+		// Get transform linked to emitter
+		const Transform & transform
+			= mgr.get_components_by_id<Transform>(emitter.game_object_id)
+				  .front()
+				  .get();
+
+		// Emit particles based on emission_rate
+		int updates
+			= calculate_update(this->update_count, emitter.data.emission_rate);
+		for (size_t i = 0; i < updates; i++) {
+			emit_particle(emitter, transform);
 		}
-		for (size_t j = 0; j < emitter.particles.size(); j++) {
-			if (emitter.particles[j].active) {
-				emitter.particles[j].update(delta_time);
+
+		// Update all particles
+		for (Particle & particle : emitter.data.particles) {
+			if (particle.active) {
+				particle.update();
 			}
 		}
+
+		// Check if within boundary
+		check_bounds(emitter, transform);
 	}
+
+	this->update_count = (this->update_count + 1) % this->MAX_UPDATE_COUNT;
 }
 
-void ParticleSystem::emit_particle(ParticleEmitter & emitter) {
-	Position initial_position = {emitter.position.x, emitter.position.y};
-	float random_angle = 0.0f;
-	if (emitter.max_angle < emitter.min_angle) {
-		random_angle = ((emitter.min_angle
-						 + (std::rand()
-							% (static_cast<uint32_t>(emitter.max_angle + 360
-													 - emitter.min_angle + 1))))
-						% 360);
-	} else {
-		random_angle = emitter.min_angle
-					   + (std::rand()
-						  % (static_cast<uint32_t>(emitter.max_angle
-												   - emitter.min_angle + 1)));
-	}
-	float angle_in_radians = random_angle * (M_PI / 180.0f);
-	float random_speed_offset = (static_cast<float>(std::rand()) / RAND_MAX)
-									* (2 * emitter.speed_offset)
-								- emitter.speed_offset;
-	float velocity_x
-		= (emitter.speed + random_speed_offset) * std::cos(angle_in_radians);
-	float velocity_y
-		= (emitter.speed + random_speed_offset) * std::sin(angle_in_radians);
-	Position initial_velocity = {velocity_x, velocity_y};
-	for (size_t i = 0; i < emitter.particles.size(); i++) {
-		if (!emitter.particles[i].active) {
-			emitter.particles[i].reset(emitter.end_lifespan, initial_position,
-									   initial_velocity);
+void ParticleSystem::emit_particle(ParticleEmitter & emitter,
+								   const Transform & transform) {
+	constexpr double DEG_TO_RAD = M_PI / 180.0;
+
+	Vector2 initial_position = emitter.data.position + transform.position;
+	double random_angle
+		= generate_random_angle(emitter.data.min_angle, emitter.data.max_angle);
+
+	double random_speed
+		= generate_random_speed(emitter.data.min_speed, emitter.data.max_speed);
+	double angle_radians = random_angle * DEG_TO_RAD;
+
+	Vector2 velocity = {random_speed * std::cos(angle_radians),
+						random_speed * std::sin(angle_radians)};
+
+	for (Particle & particle : emitter.data.particles) {
+		if (!particle.active) {
+			particle.reset(emitter.data.end_lifespan, initial_position,
+						   velocity, random_angle);
 			break;
 		}
 	}
 }
+
+int ParticleSystem::calculate_update(int count, double emission) const {
+	double integer_part = std::floor(emission);
+	double fractional_part = emission - integer_part;
+
+	if (fractional_part > 0) {
+		int denominator = static_cast<int>(1.0 / fractional_part);
+		return (count % denominator == 0) ? 1 : 0;
+	}
+
+	return static_cast<int>(emission);
+}
+
+void ParticleSystem::check_bounds(ParticleEmitter & emitter,
+								  const Transform & transform) {
+	Vector2 offset = emitter.data.boundary.offset + transform.position
+					 + emitter.data.position;
+	double half_width = emitter.data.boundary.width / 2.0;
+	double half_height = emitter.data.boundary.height / 2.0;
+
+	const double LEFT = offset.x - half_width;
+	const double RIGHT = offset.x + half_width;
+	const double TOP = offset.y - half_height;
+	const double BOTTOM = offset.y + half_height;
+
+	for (Particle & particle : emitter.data.particles) {
+		const Vector2 & position = particle.position;
+		bool within_bounds = (position.x >= LEFT && position.x <= RIGHT
+							  && position.y >= TOP && position.y <= BOTTOM);
+
+		if (!within_bounds) {
+			if (emitter.data.boundary.reset_on_exit) {
+				particle.active = false;
+			} else {
+				particle.velocity = {0, 0};
+				if (position.x < LEFT) particle.position.x = LEFT;
+				else if (position.x > RIGHT) particle.position.x = RIGHT;
+				if (position.y < TOP) particle.position.y = TOP;
+				else if (position.y > BOTTOM) particle.position.y = BOTTOM;
+			}
+		}
+	}
+}
+
+double ParticleSystem::generate_random_angle(double min_angle,
+											 double max_angle) const {
+	if (min_angle == max_angle) {
+		return min_angle;
+	} else if (min_angle < max_angle) {
+		return min_angle
+			   + static_cast<double>(std::rand()
+									 % static_cast<int>(max_angle - min_angle));
+	} else {
+		double angle_offset = (360 - min_angle) + max_angle;
+		double random_angle = min_angle
+							  + static_cast<double>(
+								  std::rand() % static_cast<int>(angle_offset));
+		return (random_angle >= 360) ? random_angle - 360 : random_angle;
+	}
+}
+
+double ParticleSystem::generate_random_speed(double min_speed,
+											 double max_speed) const {
+	if (min_speed == max_speed) {
+		return min_speed;
+	} else {
+		return min_speed
+			   + static_cast<double>(std::rand()
+									 % static_cast<int>(max_speed - min_speed));
+	}
+}
diff --git a/src/crepe/system/ParticleSystem.h b/src/crepe/system/ParticleSystem.h
index 3ac1d3f..3155df1 100644
--- a/src/crepe/system/ParticleSystem.h
+++ b/src/crepe/system/ParticleSystem.h
@@ -1,18 +1,74 @@
 #pragma once
 
-#include "../api/ParticleEmitter.h"
+#include <cstdint>
 
 namespace crepe {
-
+class ParticleEmitter;
+class Transform;
+/**
+ 	* \brief ParticleSystem class responsible for managing particle emission, updates, and bounds checking.
+ 	*/
 class ParticleSystem {
 public:
+	/**
+		* \brief Default constructor.
+		*/
 	ParticleSystem();
+
+	/**
+		* \brief Updates all particle emitters by emitting particles, updating particle states, and checking bounds.
+		*/
 	void update();
 
 private:
-	void emit_particle(ParticleEmitter & emitter); //emits a new particle
+	/**
+		* \brief Emits a particle from the specified emitter based on its emission properties.
+		* 
+		* \param emitter Reference to the ParticleEmitter.
+		* \param transform Const reference to the Transform component associated with the emitter.
+		*/
+	void emit_particle(ParticleEmitter & emitter, const Transform & transform);
+
+	/**
+		* \brief Calculates the number of times particles should be emitted based on emission rate and update count.
+		* 
+		* \param count Current update count.
+		* \param emission Emission rate.
+		* \return The number of particles to emit.
+		*/
+	int calculate_update(int count, double emission) const;
+
+	/**
+		* \brief Checks whether particles are within the emitter’s boundary, resets or stops particles if they exit.
+		* 
+		* \param emitter Reference to the ParticleEmitter.
+		* \param transform Const reference to the Transform component associated with the emitter.
+		*/
+	void check_bounds(ParticleEmitter & emitter, const Transform & transform);
 
-	float elapsed_time; //elapsed time since the last emission
+	/**
+		* \brief Generates a random angle for particle emission within the specified range.
+		* 
+		* \param min_angle Minimum emission angle in degrees.
+		* \param max_angle Maximum emission angle in degrees.
+		* \return Random angle in degrees.
+		*/
+	double generate_random_angle(double min_angle, double max_angle) const;
+
+	/**
+		* \brief Generates a random speed for particle emission within the specified range.
+		* 
+		* \param min_speed Minimum emission speed.
+		* \param max_speed Maximum emission speed.
+		* \return Random speed.
+		*/
+	double generate_random_speed(double min_speed, double max_speed) const;
+
+private:
+	//! Counter to count updates to determine how many times emit_particle is called.
+	uint32_t update_count = 0;
+	//! Determines the lowest amount of emission rate (1000 = 0.001 = 1 particle per 1000 updates).
+	static constexpr uint32_t MAX_UPDATE_COUNT = 100;
 };
 
 } // namespace crepe
diff --git a/src/crepe/system/RenderSystem.cpp b/src/crepe/system/RenderSystem.cpp
index 10211a3..17a2337 100644
--- a/src/crepe/system/RenderSystem.cpp
+++ b/src/crepe/system/RenderSystem.cpp
@@ -1,3 +1,4 @@
+#include <cmath>
 #include <functional>
 #include <vector>
 
@@ -6,7 +7,10 @@
 #include "../api/Transform.h"
 #include "../facade/SDLContext.h"
 #include "../util/log.h"
+#include "../api/ParticleEmitter.h"
+#include "../api/Vector2.h"
 
+#include "Particle.h"
 #include "RenderSystem.h"
 
 using namespace crepe;
@@ -38,24 +42,62 @@ void RenderSystem::update_camera() {
 		this->curr_cam = &cam;
 	}
 }
-void RenderSystem::render_sprites() const {
+
+bool RenderSystem::render_particle(const Sprite & sprite,
+								   const Transform & tm) {
 
 	ComponentManager & mgr = ComponentManager::get_instance();
+	SDLContext & render = SDLContext::get_instance();
+
+	auto emitters = mgr.get_components_by_id<ParticleEmitter>(sprite.game_object_id);
+
+	bool rendering_particles = false;
+
+	Transform tmp(0, Vector2{0, 0}, 0, 0);
+	tmp.scale = tm.scale;
+	for (const ParticleEmitter & em : emitters) {
+		if (!em.active) continue;
+		if (!(em.data.sprite.game_object_id == sprite.game_object_id)) continue;
 
-	std::vector<std::reference_wrapper<Sprite>> sprites
-		= mgr.get_components_by_type<Sprite>();
+		rendering_particles = true;
 
+		for (const Particle & p : em.data.particles) {
+			if (!p.active) continue;
+			tmp.position = p.position;
+			tmp.rotation = p.angle;
+			render.draw(em.data.sprite, tmp, *curr_cam);
+		}
+	}
+	return rendering_particles;
+}
+void RenderSystem::render_normal(const Sprite & sprite, const Transform & tm) {
+
+	ComponentManager & mgr = ComponentManager::get_instance();
 	SDLContext & render = SDLContext::get_instance();
+	
+	render.draw(sprite, tm, *curr_cam);
+}
+
+void RenderSystem::render() {
+
+	ComponentManager & mgr = ComponentManager::get_instance();
+
+	auto sprites = mgr.get_components_by_type<Sprite>();
 	for (const Sprite & sprite : sprites) {
-		auto transforms
-			= mgr.get_components_by_id<Transform>(sprite.game_object_id);
-		render.draw(sprite, transforms[0], *curr_cam);
+		if (!sprite.active) continue;
+		auto transform = mgr.get_components_by_id<Transform>(sprite.game_object_id);
+
+		bool rendered_particles = this->render_particle(sprite, transform[0].get());
+
+		if (rendered_particles) continue;
+
+		this->render_normal(sprite, transform[0].get());
 	}
 }
 
 void RenderSystem::update() {
 	this->clear_screen();
 	this->update_camera();
-	this->render_sprites();
+	this->render();
 	this->present_screen();
 }
diff --git a/src/crepe/system/RenderSystem.h b/src/crepe/system/RenderSystem.h
index 70db21a..468f79b 100644
--- a/src/crepe/system/RenderSystem.h
+++ b/src/crepe/system/RenderSystem.h
@@ -1,6 +1,8 @@
 #pragma once
 
 #include "api/Camera.h"
+#include "api/Sprite.h"
+#include "api/Transform.h"
 
 #include "System.h"
 
@@ -43,12 +45,22 @@ private:
 	//! Updates the active camera used for rendering.
 	void update_camera();
 
-	//! Renders all active sprites to the screen.
-	void render_sprites() const;
+	//! Renders the whole screen
+	void render();
+
+	/**
+	 * \brief Renders all the particles on the screen from a given sprite.
+	 *
+	 * \param sprite renders the particles with given texture
+	 * \param tm the Transform component for scale
+	 * \return true if particles have been rendered
+	 */
+	bool render_particle(const Sprite &, const Transform & tm);
+
+	void render_normal(const Sprite &, const Transform & tm);
 
 	/**
 	 * \todo Include color handling for sprites.
-	 * \todo Implement particle emitter rendering with sprites.
 	 * \todo Add text rendering using SDL_ttf for text components.
 	 * \todo Implement a text component and a button component.
 	 * \todo Ensure each sprite is checked for active status before rendering.