Pen Settings

HTML

CSS

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

JavaScript

Babel includes JSX processing.

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

Packages

Add Packages

Search for and use JavaScript packages from npm here. By selecting a package, an import statement will be added to the top of the JavaScript editor for this package.

Behavior

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.

Format on Save

If enabled, your code will be formatted when you actively save your Pen. Note: your code becomes un-folded during formatting.

Editor Settings

Code Indentation

Want to change your Syntax Highlighting theme, Fonts and more?

Visit your global Editor Settings.

HTML

              
                <svg
  xmlns="http://www.w3.org/2000/svg"
  xmlns:xlink="http://www.w3.org/1999/xlink"
  width="200"
  height="200"
  viewBox="0 0 1000 1000"
  style="background: #000;"
  role="img"
  aria-labelledby="solarSystemTitle"
  aria-describedby="solarSystemDescription"
>
  <title id="solarSystemTitle">A procedurally generated solar system</title>
  <desc id="solarSystemDescription">A 2D rendering of a solar system, with planets orbiting a central star.</desc>

  <!-- This element will store our graphics -->
  <g class="js-svg-wrapper"></g>
  
  <!-- This stores any global CSS styles -->
  <style>
    /* Storing values as custom properties will make them easier to change later */
    :root {
      --start-rotation: 0deg;
      --rotation-speed: 10s;
    }

    /* Set up an animation to rotate from 0 to 360 degrees */
    @keyframes orbit {
      from {
        transform: rotate(var(--start-rotation));
      }
      to {
        transform: rotate(calc(var(--start-rotation) + 360deg));
      }
    }
    .planet {
      /* Apply our animation to the planets */
      animation: orbit var(--rotation-speed) infinite linear;
      /* Within an SVG, the transform-origin is set relative to the SVG */
      /* This ensures our orbit will rotate around the center of our star */
      transform-origin: 50% 50%;
    }
  </style>
</svg>

<button class="js-refresh-button">Refresh</button>
              
            
!

CSS

              
                
/**
 * Code related to setting up the codepen, not the solar systems
 */

* {
  margin: 0;
}

body {
  display: flex;
  flex-direction: column;
  align-items: center;
}

svg {
  width: min(100vw, calc(100vh - 4.5em));
  height: auto;
}

button {
  margin-top: 1em;
  appearance: none;
}

:root {
  --hue: 200;
}

button {
  /* Text Colors */
  --text-saturation: 90%;
  --text-lightness: 40%;
  
  --text-saturation-hover: calc(var(--text-saturation) + 10%);
  --text-lightness-hover: calc(var(--text-lightness) - 5%); ;
  
  --text-saturation-active: var(--text-saturation-hover);
  --text-lightness-active: calc(var(--text-lightness) - 10%); ;
  
  --text-saturation-disabled: calc(var(--text-saturation) - 60%);
  --text-lightness-disabled: calc(var(--text-lightness) + 10%);
  
  /* Background Colors */
  --background-saturation: 0%;
  --background-lightness: 100%;
  
  --background-saturation-hover: calc(var(--background-saturation) + 80%);
  --background-lightness-hover: calc(var(--background-lightness) - 5%);
  
  --background-saturation-active: var(--background-saturation-hover);
  --background-lightness-active: calc(var(--background-lightness) - 10%);
  
  --background-saturation-disabled: calc(var(--background-saturation) + 30%);
  --background-lightness-disabled: calc(var(--background-lightness) - 10%);
  
  /* Border Colors */
  --border-saturation: 90%;
  --border-lightness: 60%;
  
  --border-saturation-hover: calc(var(--border-saturation) + 10%);
  --border-lightness-hover: calc(var(--border-lightness) - 10%);
  
  --border-saturation-active: var(--border-saturation-hover);
  --border-lightness-active: calc(var(--border-lightness) - 20%);
  
  --border-saturation-disabled: calc(var(--border-saturation) - 60%);
  --border-lightness-disabled: calc(var(--border-lightness) + 20%);
  
  /* Focus shadow styles */
  --shadow-saturation-focus: 100%;
  --shadow-lightness-focus: 85%;
  
  /* Color Styles */
  color: hsl(var(--hue), var(--text-saturation), var(--text-lightness));
  background-color: hsl(var(--hue), var(--background-saturation), var(--background-lightness)); 
  border:0.1em solid hsl(var(--hue), var(--border-saturation), var(--border-lightness)); 
  
  /* Misc. Styles */
  border-radius: 0.25em;
  cursor: pointer;
  display: inline-block;
  font-size: 1em;
  padding: 0.5em 1em;
  transition-property: box-shadow, background-color, border-color, color;
  transition-timing-function: ease-out;
  transition-duration: 0.2s;
}

button:hover {
  color: hsl(
    var(--hue), 
    var(--text-saturation-hover), 
    var(--text-lightness-hover)
  );
  
  background-color: hsl(
    var(--hue), 
    var(--background-saturation-hover), 
    var(--background-lightness-hover)
  );
  
  border-color: hsl(
    var(--hue), 
    var(--border-saturation-hover), 
    var(--border-lightness-hover)
  );
}

button:active {
  color: hsl(
    var(--hue), 
    var(--text-saturation-active), 
    var(--text-lightness-active)
  );
  
  background-color: hsl(
    var(--hue), 
    var(--background-saturation-active), 
    var(--background-lightness-active)
  );
  
  border-color: hsl(
    var(--hue), 
    var(--border-saturation-active), 
    var(--border-lightness-active)
  );
}

button:focus {
  outline: none;
  box-shadow: 0 0 0 0.25em hsl(
    var(--hue), 
    var(--shadow-saturation-focus),
    var(--shadow-lightness-focus)
  );
}

body {
  font-family: -apple-system, BlinkMacSystemFont, avenir next, avenir, helvetica neue, helvetica, Ubuntu, roboto, noto, segoe ui, arial, sans-serif; 
}

              
            
!

JS

              
                // Define a couple variables about our SVG grid
const width = 1000;
const height = 1000;

// Define some helper functions to randomize plant size and orbit distance
let randomPlanetSize = () => randomInt(10, 50);
let randomOrbitDistance = () => randomInt(100, 120);

function draw() {
  let starSize = randomInt(70, 120);
  let markup =  drawStarField() + drawStar(starSize) + addPlanets(starSize);
  
  document.querySelector(".js-svg-wrapper").innerHTML = markup;
}

function addPlanets(starSize) {
  let count = 0;
  let markup = '';

  // Set up our first planet
  let planetSize = randomPlanetSize();
  let orbitDistance = starSize + randomOrbitDistance();

  // Keep adding planets until a planet's orbital distance and size would lead
  // to it extending past our canvas
  while (orbitDistance + planetSize < 500) {
    // Add our new planet and its orbit path to our markup
    markup += drawOrbit(orbitDistance) + drawPlanet(planetSize, orbitDistance, count);

    // Prep our next planet so the while loop can check whether it's in bounds
    planetSize = randomPlanetSize();
    orbitDistance += randomOrbitDistance();
    count ++;
  }

  return markup;
}

function drawStar(size) {
  // Note upper range of red exceeds 360
  const hueRange = randomItemInArray([[330, 390], [40, 60], [190, 240]]);

  // Pass along chosen array as arguments
  let hue = randomInt(...hueRange);
  let hueDiff = hueRange[1] - hueRange[0];
  let hue2 = (hueRange[1] - hue > hue - hueRange[0]) ? randomInt(hue + hueDiff/2, hueRange[1]) : randomInt(hue - hueDiff/2, hueRange[0]);
  // If red is greater than 360,
  // use remainder
  if (hue > 360) {
    hue = hue - 360;
  }
  if (hue2 > 360) {
    hue2 = hue2 - 360;
  }
  const starColor = `hsl(${hue}, ${random(90, 100)}%, ${random(60, 70)}%)`;
  const starColorSaturatedAndLight = `hsl(${hue}, 100%, 60%)`;
  const backGlowColor = `hsl(${hue2}, ${random(80, 90)}%, ${random(40, 50)}%)`;
  const frontGlowColor = `hsl(${hue2}, 100%, ${random(50, 60)}%)`;
  
  return `
      ${starFilters({starColor, starColorSaturatedAndLight, frontGlowColor, backGlowColor, size})}
      ${starCircles({starColor, starColorSaturatedAndLight, frontGlowColor, backGlowColor, size})}
  `;
}

function starFilters({starColor, starColorSaturatedAndLight, backGlowColor, frontGlowColor, size}) {
  const blurFilterSize = 300;
  return `
      <defs>
        <filter id="star-main">
          <feTurbulence type="fractalNoise" baseFrequency="${size / 5000}" numOctaves="5" seed="${random(0, 100)}"/>
          <feDiffuseLighting lighting-color="${starColorSaturatedAndLight}" surfaceScale="${size / 20}">
            <feDistantLight azimuth="45" elevation="60" />
          </feDiffuseLighting>
          <feComposite operator="in" in2="SourceGraphic"/>
          <feGaussianBlur stdDeviation="${size / 100}"/>
        </filter>

        <filter
          id="star-glow" 
          filterUnits="userSpaceOnUse"
          x="0" 
          y="0" 
          height="${height}" 
          width="${width}"
        >
          <feGaussianBlur stdDeviation="${size / 5}"/>
        </filter>

        <filter
          id="star-secondary-glow" 
          filterUnits="userSpaceOnUse"
          x="${width/2 - size * blurFilterSize}" 
          y="${height/2 - size * blurFilterSize}" 
          height="${size * 2 * blurFilterSize}" 
          width="${size * 2 * blurFilterSize}"
        >
          <feGaussianBlur stdDeviation="${size / 5}"/>
        </filter>

        <filter
          id="star-turbulent-glow" 
        >
          <feTurbulence baseFrequency="${0.75 / size * 10}" seed="${random(0, 100)}"/>
          <feDiffuseLighting lighting-color="${starColorSaturatedAndLight}" surfaceScale="${1 * size / 20}">
            <feDistantLight azimuth="45" elevation="60" />
          </feDiffuseLighting>
          <feComposite operator="in" in2="SourceGraphic"/>
          <feGaussianBlur stdDeviation="${size / 30}"/>
        </filter>
      </defs>
  `;
}

function starCircles({starColor, starColorSaturatedAndLight, backGlowColor, frontGlowColor, size, isMain}) {
  const cx = width/2;
  const cy = height/2;
  
  return `
      <circle r="${size}" cx="${cx}" cy="${cy}" filter="url(#star-glow)" fill="${backGlowColor}" opacity="0.7"/ class="star-glow"/>
      <circle r="${size * 0.85}" cx="${cx}" cy="${cy}" filter="url(#star-turbulent-glow)" fill="${backGlowColor}" opacity="0.7" class="turbulent-glow"/>
      <circle r="${size * 0.8}" cx="${cx}" cy="${cy}" fill="${starColorSaturatedAndLight}"  class="flat"/>
      <circle r="${size * 0.75}" cx="${cx}" cy="${cy}" filter="url(#star-main)" opacity="0.9" class="main-turbulence"/>
      <circle r="${size * 0.74}" cx="${cx}" cy="${cy}" filter="url(#star-secondary-glow)" fill="${frontGlowColor}" opacity="0.7" class="inner-glow"/>
  `;
}

function drawPlanet(size, distance, count) {
  const hue = randomInt(0, 360);
  const saturation = randomInt(70, 100);
  const lightness = randomInt(50, 70);
  const color = `hsl(${hue}, ${saturation}%, ${lightness}%)`;
  const cx =  width/2 + distance;
  const cy =  height/2;

  // We'll use the current planet number to create unique IDs for our filters
  const id = `planet-${count}`;
  
  // We'll generate some random values for our turbulence
  const turbulenceType = randomBool() ? 'fractalNoise' : 'turbulence';
  const baseFrequencyX = random(0.5, 2) / size;
  const baseFrequencyY = random(2, 4) / size;
  const numOctaves = randomInt(3, 10);
  const seed = Math.random();

  // And some random values for our lighting
  const elevation = randomInt(30, 100);
  const surfaceScale = randomInt(5, 10);

  // We'll use those random valus to create our filter:
  const defs = `
      <clipPath id="${id}-shadow-clip-path">
      <circle cx="${cx}" cy="${cy}" r="${size + 2}" />
    </clipPath>
    <radialGradient id="${id}-shadow">
      <stop offset="0%" stop-color="hsla(0, 0%, 0%, 0)"></stop>
      <stop offset="90%" stop-color="hsla(0, 0%, 0%, 1)"></stop>
    </radialGradient>
    <filter id="${id}-texture">
      <feTurbulence
        type="${turbulenceType}"
        baseFrequency="${baseFrequencyX} ${baseFrequencyY}"
        seed="${seed}"
        numOctaves="${numOctaves}"
      />
      <feDiffuseLighting lighting-color="${color}" surfaceScale="${surfaceScale}">
        <feDistantLight elevation="${elevation}" />
      </feDiffuseLighting>
      <feComposite operator="in" in2="SourceGraphic"/>
    </filter>
  `;

  // And apply the filter to our planet:
  const planet = `
    <g
      class="planet"
      style="
        --start-rotation:${randomInt(0, 360)}deg;
        --rotation-speed:${distance * randomInt(40, 70)}ms;
      "
    >
      <circle
        r="${size}" 
        cx="${cx - 1}" 
        cy="${cy}"
        fill="#fff"
      />
      <circle
        r="${size}" 
        cx="${cx}" 
        cy="${cy}"
        filter="url(#${id}-texture)"
      />
      <circle cx="${cx - size}" cy="${cy}" r="${size * 2 + 2}" fill="url(#${id}-shadow)" clip-path="url(#${id}-shadow-clip-path)"/>
    </g>
  `;

  return defs + planet;
}

function drawOrbit(distance) {
  // The orbit is centered and has a radius equal to our current distance
  return `
    <circle 
      cx="${width/2}" 
      cy="${height/2}" 
      r="${distance}" 
      stroke="#ccc"
      fill="none"
    />
  `;
}

function drawStarField() {
  const id = `star-field-`;
  return `
    <defs>
      <radialGradient id="${id}-gradient-1">
        <stop offset="0%" stop-color="hsla(${random(190, 230)}, 100%, 20%, 1)" />
        <stop offset="100%" stop-color="hsla(${random(290, 360)}, 100%, 20%, 1)" />
      </radialGradient>
    </defs>
    <rect x="0%" y="0%" width="150%" height="200%" fill="url(#${id}-gradient-1)"/>
    <defs>
      <radialGradient id="${id}-gradient-2">
        <stop offset="0%" stop-color="hsla(${random(190, 230)}, 100%, 20%, 1)" />
        <stop offset="100%" stop-color="hsla(${random(290, 360)}, 100%, 20%, 1)" />
      </radialGradient>
    </defs>
    <rect x="100%" y="150%" width="150%" height="200%" fill="url(#${id}-gradient-2)" opacity="0.75"/>

    <filter id="${id}-bg">
      <feTurbulence type="fractalNoise" baseFrequency="0.01" seed="${random(0, 100)}"/> 
        <feGaussianBlur stdDeviation="10"/>       
    </filter>
    <rect width="100%" height="100%" filter="url(#${id}-bg)" opacity="0.3"/>

    <filter id="${id}-stars">
      <feTurbulence baseFrequency="0.2" seed="${random(0, 100)}"/>
      <feColorMatrix values="0 0 0 9 -4
                            0 0 0 9 -4
                            0 0 0 9 -4
                            0 0 0 0 0.5"/>
    </filter>
    <rect width="100%" height="100%" filter="url(#${id}-stars)"/>
  `;
}

/**
 * Initialize our art piece
 */
draw();

document.querySelector(".js-refresh-button").addEventListener("click", draw);

//
// Randomization Functions
//

// Return a number between two values.
function random(min, max) {
  const difference = max - min;
  return min + difference * Math.random();
}

// Returns a random integer between two values
function randomInt(min, max) {
  return Math.round(random(min, max));
}

// Returns true or false. By default the chance is 50/50 but you can pass in
// a custom probability between 0 and 1. (Higher values are more likely to
// return true.)
function randomBool(probability = 0.5) {
  return Math.random() > probability;
}

// Returns a random item from an array
function randomItemInArray(array) {
  return array[randomInt(0, array.length - 1)];
}
              
            
!
999px

Console