# Creating particle systems along a curve

Hey all,

I have a question that I can’t seem to figure out. I know it is possible to use a mouseclick to create a new particle system (just as the example code I have attached beneath). However, what I would like is to click on the mouse and add a new particle system, but that each time you click the next particle systems is placed so that you create a curve, for example a parabola?

So instead of creating points along a curve, I was wondering how I could, for example, create particle systems along a curve. To illustrate a bit further, I made this image:

Does anyone know or has a cue how to program this?

PS: the example code from processing with the particle systems

``````type or ArrayList<ParticleSystem> systems;

void setup() {
size(640, 360);
systems = new ArrayList<ParticleSystem>();
}

void draw() {
background(0);
for (ParticleSystem ps : systems) {
ps.run();
}
if (systems.isEmpty()) {
fill(255);
textAlign(CENTER);
text("click mouse to add particle systems", width/2, height/2);
}
}

void mousePressed() {
}

class ParticleSystem {

ArrayList<Particle> particles;    // An arraylist for all the particles
PVector origin;                   // An origin point for where particles are birthed

ParticleSystem(int num, PVector v) {
particles = new ArrayList<Particle>();   // Initialize the arraylist
origin = v.copy();                        // Store the origin point
for (int i = 0; i < num; i++) {
}
}

void run() {
// Cycle through the ArrayList backwards, because we are deleting while iterating
for (int i = particles.size()-1; i >= 0; i--) {
Particle p = particles.get(i);
p.run();
particles.remove(i);
}
}
}

Particle p;
// Add either a Particle or CrazyParticle to the system
if (int(random(0, 2)) == 0) {
p = new Particle(origin);
}
else {
p = new CrazyParticle(origin);
}
}

}
// A method to test if the particle system still has particles
return particles.isEmpty();
}
}

class CrazyParticle extends Particle {
float theta;
CrazyParticle(PVector l) {
super(l);
theta = 0.0;
}

void update() {
super.update();
float theta_vel = (velocity.x * velocity.mag()) / 10.0f;
theta += theta_vel;
}

void display() {
super.display();
pushMatrix();
translate(position.x, position.y);
rotate(theta);
stroke(255, lifespan);
line(0, 0, 25, 0);
popMatrix();
}
}

// A simple Particle class
class Particle {
PVector position;
PVector velocity;
PVector acceleration;
float lifespan;

Particle(PVector l) {
acceleration = new PVector(0, 0.05);
velocity = new PVector(random(-1, 1), random(-2, 0));
position = l.copy();
lifespan = 255.0;
}

void run() {
update();
display();
}

void update() {
lifespan -= 2.0;
}

// Method to display
void display() {
stroke(255, lifespan);
fill(255, lifespan);
ellipse(position.x, position.y, 8, 8);
}

// Is the particle still useful?
return (lifespan < 0.0);
}
}paste code here
``````
1 Like

Hi,

You are almost there. Now, the only thing you need to do is to define a function that as the shape you want your curve to have. Then simply use the values generated by that function instead of the mouseX and mouseY variables.

For example:

``````ArrayList<ParticleSystem> systems;

void setup() {
size(640, 360);
systems = new ArrayList<ParticleSystem>();

// Add the particule system based on the function f
for (int x = 0; x < width; x += 20) {
}

}

// the function f
float f(float x) {
return height * (- x * x + width * x)/(- width * width / 4 + width * width / 2);
}

void draw() {
background(0);
for (ParticleSystem ps : systems) {
ps.run();
}
if (systems.isEmpty()) {
fill(255);
textAlign(CENTER);
text("click mouse to add particle systems", width/2, height/2);
}
}

void mousePressed() {
}

class ParticleSystem {

ArrayList<Particle> particles;    // An arraylist for all the particles
PVector origin;                   // An origin point for where particles are birthed

ParticleSystem(int num, PVector v) {
particles = new ArrayList<Particle>();   // Initialize the arraylist
origin = v.copy();                        // Store the origin point
for (int i = 0; i < num; i++) {
}
}

void run() {
// Cycle through the ArrayList backwards, because we are deleting while iterating
for (int i = particles.size()-1; i >= 0; i--) {
Particle p = particles.get(i);
p.run();
particles.remove(i);
}
}
}

Particle p;
// Add either a Particle or CrazyParticle to the system
if (int(random(0, 2)) == 0) {
p = new Particle(origin);
} else {
p = new CrazyParticle(origin);
}
}

}
// A method to test if the particle system still has particles
return particles.isEmpty();
}
}

class CrazyParticle extends Particle {
float theta;
CrazyParticle(PVector l) {
super(l);
theta = 0.0;
}

void update() {
super.update();
float theta_vel = (velocity.x * velocity.mag()) / 10.0f;
theta += theta_vel;
}

void display() {
super.display();
pushMatrix();
translate(position.x, position.y);
rotate(theta);
stroke(255, lifespan);
line(0, 0, 25, 0);
popMatrix();
}
}

// A simple Particle class
class Particle {
PVector position;
PVector velocity;
PVector acceleration;
float lifespan;

Particle(PVector l) {
acceleration = new PVector(0, 0.05);
velocity = new PVector(random(-1, 1), random(-2, 0));
position = l.copy();
lifespan = 255.0;
}

void run() {
update();
display();
}

void update() {
lifespan -= 2.0;
}

// Method to display
void display() {
stroke(255, lifespan);
fill(255, lifespan);
ellipse(position.x, position.y, 8, 8);
}

// Is the particle still useful?
return (lifespan < 0.0);
}
}

``````
1 Like

@tryingtogetagrip not sure if it’s what you want, but:

``````void mousePressed() {
for (int x = 0; x < width; x+=70) {
float y = sq((x-width/2)/15);