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#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;
}
}
}
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