Fireworks for Processing

fireworks.pde

/**
 * Fireworks for Processing
 * Copyright (c) 2018 Koichi OKADA. All rights reserved;
 * This code is distributed under the MIT license.
 */

int MaxLife = 255;
int N = 500;

class Fire {
    double x, y, vx, vy, ax, ay;
    int life;
public:
    Fire() {
        init(width / 2, height / 2, 2);
    }
    Fire(int x, int y, double v) {
        init(x, y, v);
    }
    void init(int _x, int _y, double _v) {
        x = _x;
        y = _y;
        double v = random(_v);
        double r = random(2 * 3.14);
        vx = v * cos(r);
        vy = v * sin(r) - 1;
        ax = 0;
        ay = 0.01;
        life = MaxLife;
    }
    void step() {
        vx += ax;
        vy += ay;
        x += vx;
        y += vy;
        life--;
    }
    void draw() {
        int c = 255 - MaxLife + life;
        //stroke(random(50), random(255), random(255), 100);
        stroke(c, c, c, 100);
        //int x = random(width);
        //int y = random(height);
        line(x, y, x, y);
    }
    bool is_alive() {
        return 0 < life;
    }
}

class Fireworks {
    ArrayList<Fire> f;
public:
    Fireworks() {
        f = new ArrayList<Fire>();
    }
    void fire(int x, int y, double v) {
        for (int i = 0; i < N; i++) {
            f.add(new Fire(x, y, v));
        }
    }
    void step() {
        for (int i = 0; i < f.size(); i++) {
            f.get(i).step();
        }
    }
    void draw() {
        step();
        for (int i = 0; i < f.size(); i++) {
            f.get(i).draw();
        }
        cleanup();
    }
    void cleanup() {
        for (int i = f.size() - 1; 0 <= i; i--) {
            if (!f.get(i).is_alive()) {
                f.remove(i);
            }
        }
    }
}

Fireworks fw;

void setup() {
    background(0);
    size(300, 300); 
    strokeWeight(4);
    frameRate(30);
    fw = new Fireworks();
    fw.fire(width / 2, height / 2, 2);
} 

void draw() {
    background(0);
    fw.draw();
}

void mousePressed() {
    fw.fire(mouseX, mouseY, random(0, 4));
}

Ported to p5js.

• Fireworks for p5js