Coding Assignment Week #2 – Sand Much?

INSPIRATION

Last week I went to the outer Falcon field for my cricket practice and saw sand being pushed aside, and thrown into the air as people walked. I decided to take a closer look and base this week’s coding assignment on this nature of sand flying in the air. Here is a video of what it looked like. I was unable to get a good video of the sand flying in the air (it was so thin and dispersed that it barely showed in the video), so I uploaded one taken from the internet:

CONCEPT

The concept of my assignment this week is to have sand particles initially at the bottom of the screen, and then depending on the movement of the mouse, apply acceleration to the sand particles to have them appear as if flying in the air. I also added a bit of gravitational acceleration to the sand particles to make the simulation more realistic and have the particles settle down after a while.

MOOD BOARD

Before I started coding, I prepared a mood board for my project. This gave me clarity on the vision I was trying to build towards.

CODE & WORKING VIDEO

I have to admit it was pretty hard to code it and I struggled to model the behaviour accurately. After many failed attempts and tweaking the parameters of particle acceleration and gravity, I could get something close to what I observed.

Here are the various attempts and outputs I got:

For the code part, I built on the mover class sketch we saw in class – having the circle accelerate in the direction of the mouse. I used that as a skeleton for my program and added other features/variables and components to make it more complex and achieve the desired results.

class Particle {
  constructor() {
    let x = randomGaussian(width/2,100); // to have all particles near the center and close to ground initially
    let y = random(height-20, height);
    this.position = createVector(x, y);
    this.velocity = createVector(0, 0);
    this.acceleration = createVector(0, 0);
    this.gravity = createVector(0, 0);
    this.netAcc = createVector(0, 0); // sum of particle acceleration and gravity
    this.scaleFactor = random(0.01); // scale the acc by what factor?
  }

  update() {
  
  let mouse = createVector(mouseX, mouseY);

  // compute direction of acc
  let dir = p5.Vector.sub(mouse, this.position);
  dir.normalize(); // normalize
  dir.mult(-1*this.scaleFactor); // scale

  // accelerate only if mouse is in Screen
  if (mouseX < width && mouseX > 0 && mouseY > 0) {
    this.acceleration = dir;
    this.gravity = createVector(0,0.005);
    this.centerGravity = createVector(0,0.001);
    this.netAcc = p5.Vector.add(this.acceleration, this.gravity);
    this.velocity.add(this.netAcc);
    this.velocity.limit(5);
    this.position.add(this.velocity);
  }
    else {
      // print(this.acceleration);
      if (this.acceleration != 0) { // change acceleration direction to have particles come back
        this.acceleration.x *= -1;
        this.acceleration.y *= -1; 
      }
    }
  constrain(this.position.y, 0, height);
}

  display() {
    push()
    stroke(225,191,146);
    strokeWeight(2);
    fill(127);
    ellipse(this.position.x, this.position.y, 2, 2);
    pop();
  }

  checkEdges() {
    if (this.position.x > width) {
      this.position.x = 0;
    } else if (this.position.x < 0) {
      this.position.x = width;
    }

    if (this.position.y > height) {
      this.position.y = height;
      this.acceleration = 0;
    } else if (this.position.y < 0) {
      this.position.y = height;
      // this.acceleration.y *= -1;
    }
  }
}

let particles = []; // array to strore all sand particles
let num = 1000; // number of particles in the system

function setup() {
  // background(51);
  createCanvas(400, 400);
  for (let i = 0; i < num; i++)
    particles[i] = new Particle(); //populate particle array
}

function draw() {
  
  background(189,246,254);
  
  for (let i = 0; i < num; i++) {
    particles[i].update();
    particles[i].checkEdges();
    particles[i].display();
  }
}

P5 SKETCH

https://editor.p5js.org/shreyagoel81601/sketches/luBPK9fMi

FUTURE WORK AND IMPROVEMENTS

There is a lot that could be improved in this project. While it is close to stimulating sand flying in the air, it is not completely accurate. It is because once the sand particles go up in air, they must come down (at a faster rate than what it is right now), and that cannot be achieved only by acceleration. We will have to play a bit with forces there. We could also add wind direction and air resistance to make it more realistic. Also, currently, the acceleration keeps increasing and we move the mouse, but that is not a real-life scenario. If someone walks past the sand or kicks it, the force is momentous and not ongoing. So this also could be improved once we learn about forces and modelling that.