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#include <chrono>
#include <cmath>
#include <cstdlib>
#include <ctime>
#include "../api/ParticleEmitter.h"
#include "../api/Transform.h"
#include "../manager/ComponentManager.h"
#include "../manager/LoopTimerManager.h"
#include "ParticleSystem.h"
using namespace crepe;
void ParticleSystem::update() {
// Get all emitters
const Mediator & mediator = this->mediator;
LoopTimerManager & loop_timer = mediator.loop_timer;
ComponentManager & mgr = mediator.component_manager;
float dt = loop_timer.get_scaled_fixed_delta_time().count();
RefVector<ParticleEmitter> emitters = mgr.get_components_by_type<ParticleEmitter>();
for (ParticleEmitter & emitter : emitters) {
// 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
emitter.spawn_accumulator = emitter.data.emission_rate * dt;
while (emitter.spawn_accumulator >= 1.0) {
this->emit_particle(emitter, transform);
emitter.spawn_accumulator -= 1.0;
}
// Update all particles
for (Particle & particle : emitter.particles) {
if (particle.active) {
particle.update(dt);
}
}
// Check if within boundary
this->check_bounds(emitter, transform);
}
}
void ParticleSystem::emit_particle(ParticleEmitter & emitter, const Transform & transform) {
constexpr float DEG_TO_RAD = M_PI / 180.0;
vec2 initial_position = emitter.data.offset + transform.position;
float random_angle
= this->generate_random_angle(emitter.data.min_angle, emitter.data.max_angle);
float random_speed
= this->generate_random_speed(emitter.data.min_speed, emitter.data.max_speed);
float angle_radians = random_angle * DEG_TO_RAD;
vec2 velocity
= {random_speed * std::cos(angle_radians), random_speed * std::sin(angle_radians)};
for (Particle & particle : emitter.particles) {
if (!particle.active) {
particle.reset(emitter.data.end_lifespan, initial_position, velocity,
random_angle);
break;
}
}
}
void ParticleSystem::check_bounds(ParticleEmitter & emitter, const Transform & transform) {
vec2 offset = emitter.data.boundary.offset + transform.position + emitter.data.offset;
float half_width = emitter.data.boundary.width / 2.0;
float half_height = emitter.data.boundary.height / 2.0;
float left = offset.x - half_width;
float right = offset.x + half_width;
float top = offset.y - half_height;
float bottom = offset.y + half_height;
for (Particle & particle : emitter.particles) {
const vec2 & position = particle.position;
bool within_bounds = (position.x >= left && position.x <= right && position.y >= top
&& position.y <= bottom);
//if not within bounds do a reset or stop velocity
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;
}
}
}
}
float ParticleSystem::generate_random_angle(float min_angle, float max_angle) const {
if (min_angle == max_angle) {
return min_angle;
} else if (min_angle < max_angle) {
return min_angle
+ static_cast<float>(std::rand() % static_cast<int>(max_angle - min_angle));
} else {
float angle_offset = (360 - min_angle) + max_angle;
float random_angle
= min_angle + static_cast<float>(std::rand() % static_cast<int>(angle_offset));
return (random_angle >= 360) ? random_angle - 360 : random_angle;
}
}
float ParticleSystem::generate_random_speed(float min_speed, float max_speed) const {
if (min_speed == max_speed) {
return min_speed;
} else {
return min_speed
+ static_cast<float>(std::rand() % static_cast<int>(max_speed - min_speed));
}
}
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