Particle Effects

As a child camping isn’t what I would have called my favorite activity. The most memorable part for me was always putting together a nice fire and watching how they burned. No matter how many times I had seen them they always managed to amaze and entertain me.   The sample program uses particles to create the flame effect. Particles are quite common in video games, one example being the classic game Asteroids which used particles for the explosions. Particles are generally used for aesthetic purposes to provide extra detail to animations. [raw] [/raw] The code for the particle class is below. The particles use PVectors for the position and velocity variables as a vector is used to store both an x and y value. The position is instantiated with arguments from the constructor whereas the velocity is calculated based off of the direction of the particle. Each particle is given a "life" value which is slightly randomized which determines how long it will appear on screen. The particles movement is also slightly randomized to create more natural movement rather than having particles that move straight in one direction.

class particle {
  PVector position, velocity; //particle position & velocity stored in vectors
  int dir, radius, r, g ,b; //variables for direction, radius and RGB values (for colour)
  int life = (int) random(75, 100); //life variable
  
 //particle constructor 
 particle(float tmpx, float tmpy, int tmpdir, int tmpradius, int tmpr, int tmpg, int tmpb) {
   //instantiation of all variables
   position = new PVector(tmpx, tmpy);
   r = tmpr;g = tmpg;b = tmpb;
   dir = tmpdir; // -1 = left, 1 = right, -2 = up, 2 = down
   if (dir == 0) {
    dir = floor(random(-1, -2)); //insures no particle has no direction
   }
   radius = tmpradius;
   velocity = new PVector (0, 0);
 }
 
 void show() {
   updatePosition();
   life--;
   fill(r, g, b);
   rect(position.x, position.y, radius, radius);
 }
 
 void updatePosition() {
   //moves particle based on direction with slight offsets to look less linear
   if (dir % 2 != 0) {
    velocity.x = dir + random(-0.5, 0.5); 
    velocity.y = random(-2, 2);
   }
   if (dir % 2 == 0) {
    velocity.y = dir / 2 + random(-0.5, 0.5); 
    velocity.x = random(-2, 2);
   }
   position.add(velocity); //adds velocity vector to position vector
 }
}

The code for the rest of the demo can be found down below or at: https://www.ktbyte.com/projects/project/78231.

ArrayList particleList = new ArrayList(); //creates an array list to store particles (array list rather than array since amount will vary)
campfire fire; //campfire object

void setup() {
  size(480, 360);
  rectMode(CENTER);
  noStroke();
  
  fire = new campfire(width / 2, height - 40); //adds campire to bottom of the screen
}

void mouseDragged() {
  //creates randomly colored particles when the mouse is dragged
    particleList.add(new particle(mouseX, mouseY, int(random(-3, 3)),
    4, int(random(255)), int(random(255)), int(random(255)))); //creates particles
}

void draw() {
  background(19, 24, 98);
  fill(255);
  text("Drag your mouse to create random particles!", 10, 20);
  fire.show();
  for (int i = 0; i < particleList.size(); i++) {
    particleList.get(i).show(); //shows & updates all the particles
    if (particleList.get(i).life <= 0) {
      particleList.remove(i); //removes a particle once it's "life" hits zero
    }
  }
}

class particle {
  PVector position, velocity; //particle position & velocity stored in vectors
  int dir, radius, r, g ,b; //variables for direction, radius and RGB values (for colour)
  int life = (int) random(75, 100); //life variable
  
 //particle constructor 
 particle(float tmpx, float tmpy, int tmpdir, int tmpradius, int tmpr, int tmpg, int tmpb) {
   //instantiation of all variables
   position = new PVector(tmpx, tmpy);
   r = tmpr;g = tmpg;b = tmpb;
   dir = tmpdir; // -1 = left, 1 = right, -2 = up, 2 = down
   if (dir == 0) {
    dir = floor(random(-1, -2)); //insures no particle has no direction
   }
   radius = tmpradius;
   velocity = new PVector (0, 0);
 }
 
 void show() {
   updatePosition();
   life--;
   fill(r, g, b);
   rect(position.x, position.y, radius, radius);
 }
 
 void updatePosition() {
   //moves particle based on direction with slight offsets to look less linear
   if (dir % 2 != 0) {
    velocity.x = dir + random(-0.5, 0.5); 
    velocity.y = random(-2, 2);
   }
   if (dir % 2 == 0) {
    velocity.y = dir / 2 + random(-0.5, 0.5); 
    velocity.x = random(-2, 2);
   }
   position.add(velocity); //adds velocity vector to position vector
 }
}

class campfire {
 PVector position;
 
  //campfire constructor
 campfire(float tmpx, float tmpy) {
   position = new PVector(tmpx, tmpy);
 }
 
 void show() {
   //draws and rotates the "logs"
   pushMatrix();
   translate(position.x, position.y);
   rotate(radians(90));
   fill(70, 40, 10);
   rect(0, 0, 80, 20);
   rotate(radians(45));
   fill(80, 70, 10);
   rect(0, 0, 80, 20);
   rotate(radians(-90));
   fill(90, 60, 10);
   rect(0, 0, 80, 20);
   popMatrix();
   fill(90);
   rect(position.x, position.y + 30, 80, 30);
   //creates the fire particles
   particleList.add(new particle(position.x + random(-20, 20), position.y + random(-10, 10), -2, 4, int(random(200, 250)), 140, 45));
 }
}