1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
|
#include <cmath>
#include <cstdlib>
#include <ctime>
#include "../api/ParticleEmitter.h"
#include "../api/Transform.h"
#include "../manager/ComponentManager.h"
#include "ParticleSystem.h"
using namespace crepe;
void ParticleSystem::update() {
// Get all emitters
ComponentManager & mgr = this->mediator.component_manager;
RefVector<ParticleEmitter> emitters = mgr.get_components_by_type<ParticleEmitter>();
double dt = LoopTimer::get_instance().get_fixed_delta_time();
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
int spawn_amount = emitter.data.emission_rate * dt;
while (emitter.data.spawn_accumulator >= 1.0) {
emit_particle(emitter, transform);
emitter.data.spawn_accumulator -= 1.0;
}
// Update all particles
for (Particle & particle : emitter.data.particles) {
if (particle.active) {
particle.update(dt);
}
}
// Check if within boundary
this->check_bounds(emitter, transform);
}
this->update_count = (this->update_count + 1) % this->MAX_UPDATE_COUNT;
}
void ParticleSystem::emit_particle(ParticleEmitter & emitter, const Transform & transform) {
constexpr float DEG_TO_RAD = M_PI / 180.0;
vec2 initial_position = emitter.data.position + transform.position;
float random_angle = generate_random_angle(emitter.data.min_angle, emitter.data.max_angle);
float random_speed = 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.data.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.position;
float half_width = emitter.data.boundary.width / 2.0;
float half_height = emitter.data.boundary.height / 2.0;
const float LEFT = offset.x - half_width;
const float RIGHT = offset.x + half_width;
const float TOP = offset.y - half_height;
const float BOTTOM = offset.y + half_height;
for (Particle & particle : emitter.data.particles) {
const vec2 & 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;
}
}
}
}
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));
}
}
|