move systems + update contributing.md

1 files changed, 62 insertions, 0 deletions

diff --git a/src/crepe/system/ParticleSystem.cpp b/src/crepe/system/ParticleSystem.cpp
new file mode 100644
index 0000000..367c7d8
--- /dev/null
+++ b/src/crepe/system/ParticleSystem.cpp
@@ -0,0 +1,62 @@
+#include <cmath>
+#include <ctime>
+
+#include "../api/ParticleEmitter.h"
+#include "../ComponentManager.h"
+
+#include "ParticleSystem.h"
+
+using namespace crepe;
+
+ParticleSystem::ParticleSystem() : elapsed_time(0.0f) {}
+
+void ParticleSystem::update() {
+	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);
+		}
+		for (size_t j = 0; j < emitter.particles.size(); j++) {
+			if (emitter.particles[j].active) {
+				emitter.particles[j].update(delta_time);
+			}
+		}
+	}
+}
+
+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);
+			break;
+		}
+	}
+}