Smoke Particle System
by Daniel Shiffman
A basic smoke effect using a particle system. Each particle is rendered as an alpha masked image.
/**
* Smoke Particle System
* by Daniel Shiffman.
*
* A basic smoke effect using a particle system. Each particle
* is rendered as an alpha masked image.
*/
ParticleSystem ps;
void setup() {
size(640, 360);
PImage img = loadImage("texture.png");
ps = new ParticleSystem(0, new PVector(width/2, height-60), img);
}
void draw() {
background(0);
// Calculate a "wind" force based on mouse horizontal position
float dx = map(mouseX, 0, width, -0.2, 0.2);
PVector wind = new PVector(dx, 0);
ps.applyForce(wind);
ps.run();
for (int i = 0; i < 2; i++) {
ps.addParticle();
}
// Draw an arrow representing the wind force
drawVector(wind, new PVector(width/2, 50, 0), 500);
}
// Renders a vector object 'v' as an arrow and a position 'loc'
void drawVector(PVector v, PVector loc, float scayl) {
pushMatrix();
float arrowsize = 4;
// Translate to position to render vector
translate(loc.x, loc.y);
stroke(255);
// Call vector heading function to get direction (note that pointing up is a heading of 0) and rotate
rotate(v.heading());
// Calculate length of vector & scale it to be bigger or smaller if necessary
float len = v.mag()*scayl;
// Draw three lines to make an arrow (draw pointing up since we've rotate to the proper direction)
line(0, 0, len, 0);
line(len, 0, len-arrowsize, +arrowsize/2);
line(len, 0, len-arrowsize, -arrowsize/2);
popMatrix();
}
// A simple Particle class, renders the particle as an image
class Particle {
PVector loc;
PVector vel;
PVector acc;
float lifespan;
PImage img;
Particle(PVector l, PImage img_) {
acc = new PVector(0, 0);
float vx = randomGaussian()*0.3;
float vy = randomGaussian()*0.3 - 1.0;
vel = new PVector(vx, vy);
loc = l.copy();
lifespan = 100.0;
img = img_;
}
void run() {
update();
render();
}
// Method to apply a force vector to the Particle object
// Note we are ignoring "mass" here
void applyForce(PVector f) {
acc.add(f);
}
// Method to update position
void update() {
vel.add(acc);
loc.add(vel);
lifespan -= 2.5;
acc.mult(0); // clear Acceleration
}
// Method to display
void render() {
imageMode(CENTER);
tint(255, lifespan);
image(img, loc.x, loc.y);
// Drawing a circle instead
// fill(255,lifespan);
// noStroke();
// ellipse(loc.x,loc.y,img.width,img.height);
}
// Is the particle still useful?
boolean isDead() {
if (lifespan <= 0.0) {
return true;
} else {
return false;
}
}
}// A class to describe a group of Particles
// An ArrayList is used to manage the list of Particles
class ParticleSystem {
ArrayList<Particle> particles; // An arraylist for all the particles
PVector origin; // An origin point for where particles are birthed
PImage img;
ParticleSystem(int num, PVector v, PImage img_) {
particles = new ArrayList<Particle>(); // Initialize the arraylist
origin = v.copy(); // Store the origin point
img = img_;
for (int i = 0; i < num; i++) {
particles.add(new Particle(origin, img)); // Add "num" amount of particles to the arraylist
}
}
void run() {
for (int i = particles.size()-1; i >= 0; i--) {
Particle p = particles.get(i);
p.run();
if (p.isDead()) {
particles.remove(i);
}
}
}
// Method to add a force vector to all particles currently in the system
void applyForce(PVector dir) {
// Enhanced loop!!!
for (Particle p : particles) {
p.applyForce(dir);
}
}
void addParticle() {
particles.add(new Particle(origin, img));
}
}
This example is for Processing 4+. If you have a previous version, use the examples included with your software. If you see any errors or have suggestions, please let us know.