Gravity Simulation

p5.disableFriendlyErrors = true; //tries to help speed up framerates

let system;

​

function setup() {

  paused = false;

  frameRate(120);

  createCanvas(windowWidth, windowHeight);

  clusterValue = 1.00; //affects how clustered bodies are initially

  cam = createVector(0, 0); //allows for a moveable camera

  zoom = 0.5; //Scaling factor for camera

  spawnWindow = 1200; //This dictates the size of the spawning box for the bodies

  background(0);

  noSmooth();

  ellipseMode(CENTER); //bodies are centered on their positions

  angleMode(DEGREES);

  initialBodies = 200;

  maxMass = 1;

  minMass = 1;

  densityFactor = 3;

  densityThreshold = (maxMass + minMass) * initialBodies / 4;

  G = 0.1; //Gravitational Constant for simulation

  D = 1; //Drag (Because every good physics simulation needs this option -- 0-1, lower numbers mean more drag)

  E1 = 1.0;

  E2 = 1.0;

  /*Energy lost as heat during collisions (0-1, lower numbers mean more energy loss)

  You can change the relative energy loss that the two colliding masses experience.

  E1 is the amount of energy lost from the object that will be destroyed (i.e. the less massive one)

  E2 is the amount of energy lost from the object that will survive the collision (i.e. the more massive one)

  Set both to 1 to ignore energy loss*/

  colorSet = 'normal'; //'velocity' for color based on linear velocity, 'mass' for color based on mass

  physLines = false; //toggles lines for velocity(red) and force(blue)

  colors = ['red', 'orange', 'yellow', 'lime', 'cyan', 'dodgerblue', 'mediumorchid'];

  borders = true; //toggles shape borders

  iV = 0.250; //max initial velocity magnitude

​

​

  trailsOn = false; //toggles trails

  trailLength = 10; //this affects the length of trails

​

  system = new System();

  let i = 0;

  while (i < initialBodies) {

    let p = createVector(0, spawnWindow / 2);

    p.rotate(random(0, 360));

    p.mult(random(0, 1), random(0,1));

    if (noise(5 * (p.x + spawnWindow / 2) / spawnWindow, 5 * (p.y + spawnWindow / 2) / spawnWindow) * clusterValue < 0.5 & i < initialBodies) {

      let b = new Body(p.x, p.y);

      system.addBody(b);

      i++;

    }

  }

}

​

function keyPressed() {

  if (key === 'r') {

    noiseSeed(random(-100000, 100000));

    system.bodies.splice(0, system.bodies.length);

    //reset camera

    cam.x = 0;

    cam.y = 0;

    background(0);

    let i = 0;

    while (i < initialBodies) {

      let p = createVector(0, spawnWindow / 2);

      p.rotate(random(0, 360));

      p.mult(random(0, 1), random(0,1));

      if (noise(5 * (p.x + spawnWindow / 2) / spawnWindow, 5 * (p.y + spawnWindow / 2) / spawnWindow) * clusterValue < 0.5 & i < initialBodies) {

        let b = new Body(p.x, p.y);

        system.addBody(b);

        i++;

      }

    }

    redraw();

  }

  if (key === 't') {

    trailsOn = !trailsOn;

  }

  if (key === 'b') {

    borders = !borders;

  }

  if (key === 'p') {

    paused = !paused;

  }

  if (key === 'l') {

    physLines = !physLines;

  }

  if (key === '1') {

    colorSet = 'normal';

  }

  if (key === '2') {

    colorSet = 'velocity';

  }

  if (key === '3') {

    colorSet = 'mass'

  }

}

​

function draw() {

  frameRate(120);

  background(0);

  //camera movement

  if (keyIsDown(LEFT_ARROW)) {

    cam.x += 5 / zoom;

  }

  if (keyIsDown(RIGHT_ARROW)) {

    cam.x += -5 / zoom;

  }

  if (keyIsDown(UP_ARROW)) {

    cam.y += 5 / zoom;

  }

  if (keyIsDown(DOWN_ARROW)) {

    cam.y += -5 / zoom;

  }

  //camera zooming

  if (keyIsDown(189) & zoom > 0.25) {

    zoom += -0.06;

  }

  if (keyIsDown(187) & zoom < 8) {

    zoom += 0.06;

  }

  //centers camera

  push();

  translate(width / 2, height / 2);

  scale(zoom);

  translate(-width / 2, -height / 2);

  translate(cam.x, cam.y);

  system.run();

  pop();

  //displays frame rate and # of simulated bodies

  fill(255);

  textSize(12);

  text(system.bodies.length, 10, windowHeight - 10);

  text(frameRate().toFixed(1), 10, windowHeight - 22);

}

​

function System() { //this defines the whole set of moving objects

  this.bodies = [];

}

​

System.prototype.addBody = function(b) {

  this.bodies.push(b);

}

​

System.prototype.run = function() {

  frameRate(120);

  let collided = []; //stores bodies which have been destroyed in a collision

  for (let i = this.bodies.length - 1; i >= 0; i--) {

    this.bodies[i].run(this.bodies);

    if (this.bodies[i].collided === true) {

      collided.push(i);

    }

  }

  for (let i = this.bodies.length - 1; i >= 0; i--) {

    if (paused !== true) {

      this.bodies[i].update();

    }

  }

  //removes destroyed bodies

  for (let i = 0; i < collided.length; i++) {

    this.bodies.splice(collided[i], 1);

  }

}

​

​

function Body(x, y) { //these are the objects that move

  this.position = createVector(width / 2 + x, height / 2 + y);

  this.velocity = createVector((noise(x) - 0.5) * 2 * iV, (noise(y) - 0.5) * 2 * iV);

  this.acceleration = createVector(0, 0);

  this.color = color(random(colors));

  this.mass = random(minMass, maxMass);

  this.density = pow(densityFactor, ((this.mass / densityThreshold) - (1 / densityThreshold)));

  this.size = this.mass / (this.density * 2);

  this.G = createVector(0, 0);

  this.collided = false;

  this.pPos = [this.position];

}

​

Body.prototype.accel = function(force) {

  this.acceleration.add(force);

}

​

Body.prototype.grav = function(bodies) {

  frameRate(120);

  let grav = createVector(0, 0);

  let gPoint = createVector(0, 0);

  for (let i = 0; i < bodies.length; i++) {

    let b = bodies[i];

    let rPos = p5.Vector.sub(b.position, this.position);

    let dist = rPos.mag();

    let minD = this.size / 2 + b.size / 2;

    if (dist < minD & dist > 0 & this.collided !== true) {

      this.collide(b);

    }

    if (dist >= minD & this.collided !== true) {

      let dir = p5.Vector.normalize(rPos);

      gPoint.add(dir);

      gPoint.mult(G);

      gPoint.mult(b.mass);

      gPoint.mult(this.mass);

      //limit distance to prevent absurd values for force

      if (dist >= 0.55) {

        gPoint.div(pow(dist, 2));

      } else {

        gPoint.div(pow(0.55, 2));

      }

      grav.add(gPoint);

      gPoint.mult(0);

    }

  }

  this.G.set(grav.x, grav.y);

  grav.div(this.mass);

  return grav;

}

​

Body.prototype.collide = function(b) {

  let tMass = this.mass + b.mass;

  let i1 = createVector(this.velocity.x, this.velocity.y);

  i1.mult(this.mass);

  i1.mult(E1);

  let i2 = createVector(b.velocity.x, b.velocity.y);

  i2.mult(b.mass);

  i2.mult(E2);

  let vf = p5.Vector.add(i1, i2);

  vf.div(tMass);

  if (this.mass < b.mass | this.mass === b.mass) {

    b.velocity.set(vf);

    b.mass = this.mass + b.mass;

    b.density = (pow(densityFactor, ((b.mass / densityThreshold) - (1 / densityThreshold))));

    b.size = b.mass / (b.density * 2);

    this.collided = true;

  }

}

​

Body.prototype.attract = function(bodies) {

  let g = this.grav(bodies);

  this.accel(g);

}

​

Body.prototype.update = function() {

  frameRate(120);

  this.velocity.add(this.acceleration);

  this.velocity.mult(D);

  this.position.add(this.velocity);

  if (trailsOn === true) {

    if (frameCount % 3 === 0) {

      this.pPos.push(new p5.Vector(this.position.x, this.position.y));

    }

    if (this.pPos.length > (trailLength + 1)) {

      this.pPos.splice(0, 1);

    }

  } else {

    this.pPos.splice(0, this.pPos.length);

  }

  this.acceleration.mult(0);

}

​

Body.prototype.display = function() {

  let c;

  if (colorSet === 'velocity') {

    push();

    translate(this.position.x, this.position.y);

    c = color((this.velocity.mag() / (7 * G)) * 255, 255 - ((this.velocity.mag() / (7 * G)) * 255), 0);

    if (trailsOn === true) {

      for (let i = 1; i < this.pPos.length; i++) {

        let pPos = this.pPos[i];

        let prePos = this.pPos[i - 1];

        strokeWeight(this.size / 4);

        stroke(c);

        line(pPos.x - this.position.x, pPos.y - this.position.y, prePos.x - this.position.x, prePos.y - this.position.y);

      }

    }

    if (borders === true) {

      strokeWeight(this.size / 10);

      stroke(255);

    } else {

      noStroke();

    }

    fill(c);

    ellipse(0, 0, this.size);

    noStroke();

    c.setAlpha(lerp(0, 175, 1 - (densityThreshold / (this.mass + densityThreshold / 2))));

    fill(c);

    ellipse(0, 0, this.size * 1.5);

    c.setAlpha(lerp(0, 100, 1 - (densityThreshold / (this.mass + densityThreshold / 2))));

    fill(c);

    ellipse(0, 0, this.size * 2);

    c.setAlpha(lerp(0, 50, 1 - (densityThreshold / (this.mass + densityThreshold / 2))));

    fill(c);

    ellipse(0, 0, this.size * 2.5);

    c.setAlpha(255);

    if (physLines === true) {

      strokeWeight(1);

      stroke(255, 0, 0);

      line(0, 0, this.velocity.x * 10, this.velocity.y * 10);

      stroke(0, 0, 255);

      line(0, 0, this.G.x * 5 / G, this.G.y * 5 / G);

      this.G.mult(0);

    }

    pop();

  } else if (colorSet === 'mass') {

    push();

    translate(this.position.x, this.position.y);

    c = color(0, ((2 * this.mass / densityThreshold) * 255), 255 - ((2 * this.mass / densityThreshold) * 255));

    if (trailsOn === true) {

      for (let i = 1; i < this.pPos.length; i++) {

        let pPos = this.pPos[i];

        let prePos = this.pPos[i - 1];

        strokeWeight(this.size / 4);

        stroke(c);

        line(pPos.x - this.position.x, pPos.y - this.position.y, prePos.x - this.position.x, prePos.y - this.position.y);

      }

    }

    if (borders === true) {

      strokeWeight(this.size / 10);

      stroke(255);

    } else {

      noStroke();

    }

    fill(c);

    ellipse(0, 0, this.size);

    noStroke();

    c.setAlpha(lerp(0, 175, 1 - (densityThreshold / (this.mass + densityThreshold / 2))));

    fill(c);

    ellipse(0, 0, this.size * 1.5);

    c.setAlpha(lerp(0, 100, 1 - (densityThreshold / (this.mass + densityThreshold / 2))));

    fill(c);

    ellipse(0, 0, this.size * 2);

    c.setAlpha(lerp(0, 50, 1 - (densityThreshold / (this.mass + densityThreshold / 2))));

    fill(c);

    ellipse(0, 0, this.size * 2.5);

    c.setAlpha(255);

    if (physLines === true) {

      strokeWeight(1);

      stroke(255, 0, 0);

      line(0, 0, this.velocity.x * 10, this.velocity.y * 10);

      stroke(0, 0, 255);

      line(0, 0, this.G.x * 5 / G, this.G.y * 5 / G);

      this.G.mult(0);

    }

    pop();

  } else if (colorSet !== 'mass' & colorSet !== 'velocity') {

    push();

    translate(this.position.x, this.position.y);

    if (trailsOn === true) {

      for (let i = 1; i < this.pPos.length; i++) {

        let pPos = this.pPos[i];

        let prePos = this.pPos[i - 1];

        strokeWeight(this.size / 4);

        stroke(this.color);

        line(pPos.x - this.position.x, pPos.y - this.position.y, prePos.x - this.position.x, prePos.y - this.position.y);

      }

    }

    if (borders === true) {

      strokeWeight(this.size / 10);

      stroke(255);

    } else {

      noStroke();

    }

    fill(this.color);

    ellipse(0, 0, this.size);

    noStroke();

    this.color.setAlpha(lerp(0, 175, 1 - (densityThreshold / (this.mass + densityThreshold / 2))));

    fill(this.color);

    ellipse(0, 0, this.size * 1.5);

    this.color.setAlpha(lerp(0, 100, 1 - (densityThreshold / (this.mass + densityThreshold / 2))));

    fill(this.color);

    ellipse(0, 0, this.size * 2);

    this.color.setAlpha(lerp(0, 50, 1 - (densityThreshold / (this.mass + densityThreshold / 2))));

    fill(this.color);

    ellipse(0, 0, this.size * 2.5);

    this.color.setAlpha(255);

    if (physLines === true) {

      strokeWeight(1);

      stroke(255, 0, 0);

      line(0, 0, this.velocity.x * 10, this.velocity.y * 10);

      stroke(0, 0, 255);

      line(0, 0, this.G.x * 5 / G, this.G.y * 5 / G);

      this.G.mult(0);

    }

    pop();

  }

}

​

Body.prototype.run = function(bodies) {

  frameRate(120);

  if (paused !== true) {

    this.attract(bodies);

  }

  this.display();

}