Pen Settings

CSS Base

Vendor Prefixing

Add External Stylesheets/Pens

Any URL's added here will be added as <link>s in order, and before the CSS in the editor. If you link to another Pen, it will include the CSS from that Pen. If the preprocessor matches, it will attempt to combine them before processing.

+ add another resource

You're using npm packages, so we've auto-selected Babel for you here, which we require to process imports and make it all work. If you need to use a different JavaScript preprocessor, remove the packages in the npm tab.

Add External Scripts/Pens

Any URL's added here will be added as <script>s in order, and run before the JavaScript in the editor. You can use the URL of any other Pen and it will include the JavaScript from that Pen.

+ add another resource

Use npm Packages

We can make npm packages available for you to use in your JavaScript. We use webpack to prepare them and make them available to import. We'll also process your JavaScript with Babel.

⚠️ This feature can only be used by logged in users.

Code Indentation

     

Save Automatically?

If active, Pens will autosave every 30 seconds after being saved once.

Auto-Updating Preview

If enabled, the preview panel updates automatically as you code. If disabled, use the "Run" button to update.

HTML Settings

Here you can Sed posuere consectetur est at lobortis. Donec ullamcorper nulla non metus auctor fringilla. Maecenas sed diam eget risus varius blandit sit amet non magna. Donec id elit non mi porta gravida at eget metus. Praesent commodo cursus magna, vel scelerisque nisl consectetur et.

            
                <section id="controls-wrapper">
    <label>Mass of Added Planet</label>
    <select id="masses-list">
      <option value="0.000003003">Earth</option>
      <option value="0.0009543">Jupiter</option>
      <option value="1">Sun</option>
      <option value="0.1">Red Dwarf Star</option>   
    </select>
    <button id="reset-button">Reset</button>
  </section>
  <canvas id="canvas"></canvas>
            
          
!
            
                  body {
      margin: 0;
      overflow: hidden;
      background: linear-gradient(to bottom, #cedce7 0%,#596a72 100%);      
      font-family: arial;
      font-size: 13px;
      font-weight: bold;
    }
    #controls-wrapper {
      position: absolute;
      z-index: 2;
      top: 0;
      width: 100%;
      padding: 10px;
    }
    #controls-wrapper > select, button {
      background-color: #000;
      color: #fff;
      border: 1px solid #545454;
    }
            
          
!
            
                /*
   * Gravitational n-body algorithm 
  */

  class nBodyProblem {
    constructor(params) {
      this.g = params.g;
      this.dt = params.dt;
      this.softeningConstant = params.softeningConstant;
  
      this.masses = params.masses;
    }
  
    updatePositionVectors() {
      const massesLen = this.masses.length;
  
      for (let i = 0; i < massesLen; i++) {
        const massI = this.masses[i];
  
        massI.x += massI.vx * this.dt;
        massI.y += massI.vy * this.dt;
        massI.z += massI.vz * this.dt;
      }
  
      return this;
    }
  
    updateVelocityVectors() {
      const massesLen = this.masses.length;
  
      for (let i = 0; i < massesLen; i++) {
        const massI = this.masses[i];
  
        massI.vx += massI.ax * this.dt;
        massI.vy += massI.ay * this.dt;
        massI.vz += massI.az * this.dt;
      }
    }
  
    updateAccelerationVectors() {
      const massesLen = this.masses.length;
  
      for (let i = 0; i < massesLen; i++) {
        let ax = 0;
        let ay = 0;
        let az = 0;
  
        const massI = this.masses[i];
  
        for (let j = 0; j < massesLen; j++) {
          if (i !== j) {
            const massJ = this.masses[j];
  
            const dx = massJ.x - massI.x;
            const dy = massJ.y - massI.y;
            const dz = massJ.z - massI.z;
  
            const distSq = dx * dx + dy * dy + dz * dz;
  
            const f =
              (this.g * massJ.m) /
              (distSq * Math.sqrt(distSq + this.softeningConstant));
  
            ax += dx * f;
            ay += dy * f;
            az += dz * f;
          }
        }
  
        massI.ax = ax;
        massI.ay = ay;
        massI.az = az;
      }
  
      return this;
    }
  }
  
  /*
   * Inputs for our nBodyProblem
   */
  
  const g = 39.5;
  const dt = 0.008; //0.005 years is equal to 1.825 days
  const softeningConstant = 0.15;
  
  const masses = [{
      name: "Sun", //We use solar masses as the unit of mass, so the mass of the Sun is exactly 1
      m: 1,
      x: -1.50324727873647e-6,
      y: -3.93762725944737e-6,
      z: -4.86567877183925e-8,
      vx: 3.1669325898331e-5,
      vy: -6.85489559263319e-6,
      vz: -7.90076642683254e-7
    },
    {
      name: "Mercury",
      m: 1.65956463e-7,
      x: -0.346390408691506,
      y: -0.272465544507684,
      z: 0.00951633403684172,
      vx: 4.25144321778261,
      vy: -7.61778341043381,
      vz: -1.01249478093275
    },
    {
      name: "Venus",
      m: 2.44699613e-6,
      x: -0.168003526072526,
      y: 0.698844725464528,
      z: 0.0192761582256879,
      vx: -7.2077847105093,
      vy: -1.76778886124455,
      vz: 0.391700036358566
    },
    {
      name: "Earth",
      m: 3.0024584e-6,
      x: 0.648778995445634,
      y: 0.747796691108466,
      z: -3.22953591923124e-5,
      vx: -4.85085525059392,
      vy: 4.09601538682312,
      vz: -0.000258553333317722
    },
    {
      m: 3.213e-7,
      name: "Mars",
      x: -0.574871406752105,
      y: -1.395455041953879,
      z: -0.01515164037265145,
      vx: 4.9225288800471425,
      vy: -1.5065904473191791,
      vz: -0.1524041758922603
    }
  ];
  
  /*
   * Create an instance of the nBodyProblem with the inputs above
   * We clone the masses array by parsing a stringified version of it so that we can reset the simulator with a minimum amount of fuss
   */ 
  
  const innerSolarSystem = new nBodyProblem({
    g,
    dt,
    masses: JSON.parse(JSON.stringify(masses)),   
    softeningConstant
  });
  
  /*
   * Motion trails
   */
  
  class Manifestation {
    constructor(ctx, trailLength, radius) {
      this.ctx = ctx;
    
      this.trailLength = trailLength;
  
      this.radius = radius;
  
      this.positions = [];
    }
  
    storePosition(x, y) {
      this.positions.push({
        x,
        y
      });
  
      if (this.positions.length > this.trailLength) this.positions.shift();
    }
  
    draw(x, y) {
      this.storePosition(x, y);
  
      const positionsLen = this.positions.length;
  
      for (let i = 0; i < positionsLen; i++) {
        let transparency;
        let circleScaleFactor;
  
        const scaleFactor = i / positionsLen;
  
        if (i === positionsLen - 1) {
          transparency = 1;
          circleScaleFactor = 1;
        } else {
          transparency = scaleFactor / 2;      
          circleScaleFactor = scaleFactor;
        }
  
        this.ctx.beginPath();
        this.ctx.arc(
          this.positions[i].x,
          this.positions[i].y,
          circleScaleFactor * this.radius,
          0,
          2 * Math.PI
        );
        this.ctx.fillStyle = `rgb(0, 12, 153, ${transparency})`;
  
        this.ctx.fill();
      }
    }
  }
  
  /*
   * Get the canvas element and its context from the DOM
   */
  
  const canvas = document.querySelector("#canvas");
  const ctx = canvas.getContext("2d");
  
  /*
   * Full screen action
   */
  
  const width = (canvas.width = window.innerWidth);
  const height = (canvas.height = window.innerHeight);
  
  /*
   * Animation constants
   *
   * scale is the number of pixels per astronomical units
   *
   * radius is the radius of the circle that represents the current position of a mass
   *
   * trailLength is the number of previous positions that we should draw in the motion trail
   */
  
  const scale = 70;
  const radius = 4;
  const trailLength = 35;
  
  /*
   * Iterate over the masses being simulated and add a visual manifestation for each of them
   */
  
  const populateManifestations = masses => {
    masses.forEach(
      mass =>
      (mass["manifestation"] = new Manifestation(
        ctx,
        trailLength,
        radius
      ))
    );
  };
  
  populateManifestations(innerSolarSystem.masses);

  /*
   * Click the reset button to reset the simulation
  */

  document.querySelector('#reset-button').addEventListener('click', () => {
    innerSolarSystem.masses = JSON.parse(JSON.stringify(masses));
    populateManifestations(innerSolarSystem.masses);       
  }, false);
  
  /*
   * Code for adding masses with you mouse
   */
  
  //Step 1.
  
  let mousePressX = 0;
  let mousePressY = 0;
  
  //Step 2.
  
  let currentMouseX = 0;
  let currentMouseY = 0;
  
  //Step 3.
  
  let dragging = false;
  
  //Step 4.
  
  canvas.addEventListener(
    "mousedown",
    e => {
      mousePressX = e.clientX;
      mousePressY = e.clientY;
      dragging = true;
    },
    false
  );
  
  //Step 5
  
  canvas.addEventListener(
    "mousemove",
    e => {
      currentMouseX = e.clientX;
      currentMouseY = e.clientY;
    },
    false
  );
  
  //Step 6
  
  const massesList = document.querySelector("#masses-list");
  
  canvas.addEventListener(
    "mouseup",
    e => {
      const x = (mousePressX - width / 2) / scale;
      const y = (mousePressY - height / 2) / scale;
      const z = 0;
      const vx = (e.clientX - mousePressX) / 35;
      const vy = (e.clientY - mousePressY) / 35;
      const vz = 0;
  
      innerSolarSystem.masses.push({
        m: parseFloat(massesList.value),
        x,
        y,
        z,
        vx,
        vy,
        vz,
        manifestation: new Manifestation(ctx, trailLength, radius)
      });
  
      dragging = false;
    },
    false
  );
  
  /*
   * The animate function that sets everything in motion.
   * We run it 60 times a second with the help of requestAnimationFrame
   */
  
  const animate = () => {
    /*
     * Advance our simulation by one step
     */
  
    innerSolarSystem
      .updatePositionVectors()
      .updateAccelerationVectors()
      .updateVelocityVectors();
  
    /*
     * Clear the canvas in preparation for the next drawing cycle
     */
  
    ctx.clearRect(0, 0, width, height);
  
    const massesLen = innerSolarSystem.masses.length;
  
    /*
     * Let us draw some masses!
     */
  
    for (let i = 0; i < massesLen; i++) {
      const massI = innerSolarSystem.masses[i];
  
      /*
       * The origin (x = 0, y = 0) of the canvas coordinate system is in the top left corner
       * To prevent our simulation from being centered on the top left corner, include the x and y offsets
       * So that it is centered smack in the middle of the canvas
       */
  
      const x = width / 2 + massI.x * scale;
      const y = height / 2 + massI.y * scale;
  
      /*
       * Draw our motion trail
       */
  
      massI.manifestation.draw(x, y);
  
      /*
       * If the mass has a name, draw it onto the canvas next to the leading circle of the motion trail
       */
  
      if (massI.name) {
        ctx.font = "14px Arial";
        ctx.fillText(massI.name, x + 12, y + 4);
        ctx.fill();
      }
      
      /*
       * Stop masses from escaping the bounds of the viewport
       * If either condition is met, the velocity of the mass will be reversed
       * And the mass will bounce back into the inner solar system
       */
  
      if (x < radius || x > width - radius) massI.vx = -massI.vx;
  
      if (y < radius || y > height - radius) massI.vy = -massI.vy;
    }
  
    /*
     * Draw the line which indicates direction and velocity of a mass that is about to be added when the mouse is being dragged
     */
  
    if (dragging) {
      ctx.beginPath();
      ctx.moveTo(mousePressX, mousePressY);
      ctx.lineTo(currentMouseX, currentMouseY);
      ctx.strokeStyle = "red";
      ctx.stroke();
    }
  
    requestAnimationFrame(animate);
  };
  
  animate();
            
          
!
999px
🕑 One or more of the npm packages you are using needs to be built. You're the first person to ever need it! We're building it right now and your preview will start updating again when it's ready.

Console