​

var links = [];

var meshSize = 32;

var offset = 0.2

var gravity;

var gravityAcceleration = 500;

var coefficient = 5000;

var simSteps = 5;

var shouldBeDistance;

​

function setup() {

  gravity = createVector(0, gravityAcceleration);

  createCanvas(400, 400);

  for(var y = 0; y < meshSize; y++) {

    for(var x = 0; x < meshSize; x++) {

      links.push([createVector(width * (offset + (1-offset*2) * x / meshSize), height * (offset + (1 - offset*2) * y / meshSize)), createVector()]);

    }

  }

  shouldBeDistance = links[1][0].x - links[0][0].x;

}

​

function draw() {

  background(245);

  // drawing

  for(var y = 0; y < meshSize; y++) {

    for(var x = 0; x < meshSize; x++) {

      var i = y * meshSize + x;

      var [pos, vel] = links[i];

      var neighbors = [];

      if(x > 0) neighbors.push(i-1);

      if(y > 0) neighbors.push(i-meshSize);

      if(x < meshSize-1) neighbors.push(i+1);

      if(y < meshSize-1) neighbors.push(i+meshSize);

      for(var neighbor of neighbors) {

        var [pos2, vel2] = links[neighbor];

        line(pos.x, pos.y, pos2.x, pos2.y);

      }

    }

  }

  // physics

  for(var it = 0; it < simSteps; it++) {

    for(var y = 0; y < meshSize; y++) {

      for(var x = 0; x < meshSize; x++) {

        var i = y * meshSize + x;

        var [pos, vel] = links[i];

​

        var physics = y > 0 || x % 3 >= 2;

        if(!physics) continue;

​

        // gravity

        vel.add(normalize(gravity));

​

        // spring forces

        var neighbors = [];

        if(x > 0) neighbors.push(i-1);

        if(y > 0) neighbors.push(i-meshSize);

        if(x < meshSize-1) neighbors.push(i+1);

        if(y < meshSize-1) neighbors.push(i+meshSize);

​

        for(neighbor of neighbors) {

          [pos2, vel2] = links[neighbor];

​

          var dir = p5.Vector.sub(pos2, pos);

          var distance = dir.mag();

          var extension = distance - shouldBeDistance;

          dir.setMag(extension * coefficient);

          vel.add(normalize(dir));

        }

        // mouse forces

        var mouseVector = pos.copy();

        mouseVector.sub(createVector(mouseX, mouseY));

        mouseVector.setMag((mouseVector.mag() ** (-1))*20000);

        if(mouseIsPressed) {

          vel.add(normalize(mouseVector));

        }

      }

    }

    for(y = 0; y < meshSize; y++) {

      for(x = 0; x < meshSize; x++) {

        i = y * meshSize + x;

        [pos, vel] = links[i];

        // integrate

        pos.add(normalize(vel));

      }

    }

  }

}

​

function normalize(vec) {

  return p5.Vector.mult(vec, max(min(deltaTime, 40), 40)/1000/simSteps);

}

​