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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.

HTML

              
                <canvas id="canvas" title="Click to generate new pattern"></canvas>
              
            
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CSS

              
                body, html {
  margin: 0;
}

canvas {
  display: block;
  cursor: pointer;
}
              
            
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JS

              
                /*
  Johan Karlsson, 2020
  https://twitter.com/DonKarlssonSan
  MIT License, see Details View
  
  https://en.wikipedia.org/wiki/Delaunay_triangulation
  
  https://en.wikipedia.org/wiki/Bowyer%E2%80%93Watson_algorithm
  
  https://en.wikipedia.org/wiki/Circumscribed_circle
*/

class Triangle {
  constructor(a, b, c) {
    this.a = a;
    this.b = b;
    this.c = c;
  }
  
  vertexes() {
    return [this.a, this.b, this.c];
  }
  
  edges() {
    return [
      [this.a, this.b],
      [this.b, this.c],
      [this.c, this.a]
    ];
  }
  
  sharesAVertexWith(triangle) {
    // TODO: optimize me please!
    for(let i = 0; i < 3; i++) {
      for(let j = 0; j < 3; j++) {
        let v = this.vertexes()[i];
        let vv = triangle.vertexes()[j];
        if(v.equals(vv)) {
          return true;
        }
      }
    }
    return false;
  }

  hasEdge(edge) {
    for(let i = 0; i < 3; i++) {
      let e = this.edges()[i];
      if(e[0].equals(edge[0]) && e[1].equals(edge[1]) || 
         e[1].equals(edge[0]) && e[0].equals(edge[1])) {
        return true;
      }
    }
    return false;
  }
  
  circumcenter() {
    let d = 2 * (this.a.x * (this.b.y - this.c.y) + 
                 this.b.x * (this.c.y - this.a.y) + 
                 this.c.x * (this.a.y - this.b.y));
    
    let x = 1 / d * ((this.a.x * this.a.x + this.a.y * this.a.y) * (this.b.y - this.c.y) +
                     (this.b.x * this.b.x + this.b.y * this.b.y) * (this.c.y - this.a.y) + 
                     (this.c.x * this.c.x + this.c.y * this.c.y) * (this.a.y - this.b.y));
    
    let y = 1 / d * ((this.a.x * this.a.x + this.a.y * this.a.y) * (this.c.x - this.b.x) + 
                     (this.b.x * this.b.x + this.b.y * this.b.y) * (this.a.x - this.c.x) + 
                     (this.c.x * this.c.x + this.c.y * this.c.y) * (this.b.x - this.a.x));
    
    return new Vector(x, y);
  }
  
  circumradius() {
    return this.circumcenter().sub(this.a).getLength();    
  }
  
  pointIsInsideCircumcircle(point) {
    let circumcenter = this.circumcenter();
    let circumradius = circumcenter.sub(this.a).getLength();
    let dist = point.sub(circumcenter).getLength();
    return dist < circumradius;
  }
  
  draw() {
    let c = this.circumcenter();
    ctx.save();
    let color = getColor(this.a, this.b)
    ctx.strokeStyle = color;
    ctx.fillStyle = color;
    
    ctx.beginPath();
    ctx.lineTo(this.a.x, this.a.y);
    ctx.lineTo(this.b.x, this.b.y);
    ctx.lineTo(this.c.x, this.c.y);
    ctx.closePath();
    ctx.fill();
    ctx.stroke();
    
    if(image) {
      ctx.clip();
      ctx.translate(c.x, c.y);
      let angle = Math.random() * Math.PI * 2;
      ctx.rotate(angle);
      let leftMargin = -image.width / 2;
      let topMargin = -image.height / 2;
      ctx.globalAlpha = 0.07;
      ctx.drawImage(image, leftMargin, topMargin); 
    }
    ctx.restore();
  }
}

let canvas;
let ctx;
let w, h;
let simplex;
let zoom;
let image;

function setup() {
  canvas = document.querySelector("#canvas");
  ctx = canvas.getContext("2d");
  reset();
  window.addEventListener("resize", () => {
    reset();
    draw();
  });
  canvas.addEventListener("click", draw);
  loadImage().then(img => {
    image = img;
    draw();
  });
}

function getColor(vec1, vec2) {
  let n = (simplex.noise2D(vec1.x / zoom, vec1.y / zoom) + 1) * 0.5;
  let hue = 360 * n;
  
  var gradient = ctx.createLinearGradient(vec1.x, vec1.y, vec2.x, vec2.y);
  let color1= `hsl(${hue}, 70%, 50%)`;
  let color2= `hsl(${hue + 90}, 70%, 50%)`;
  
  gradient.addColorStop(0, color1);
  gradient.addColorStop(1, color2);

  return gradient;
}

function loadImage() {
  return new Promise((resolve, reject) => {
    let image = new Image();
    image.crossOrigin = "anonymous";
    // Sand image from:
    // https://www.merckgroup.com/en/products/pm/117237.html
    image.src = "https://s3-us-west-2.amazonaws.com/s.cdpn.io/254249/sand1.jpg";
    image.onload = () => {
      resolve(image);
    };
    image.onerror = error => {
      reject(error.srcElement.src);
    }
  });
}

function reset() {
  w = canvas.width = window.innerWidth;
  h = canvas.height = window.innerHeight;
}

function getRandomPoints() {
  let extra = 40;
  let pointList = [
    new Vector(-extra, -extra),
    new Vector(-extra, h + extra),
    new Vector(w + extra, -extra),
    new Vector(w + extra, h + extra)
  ];
  
  let rStep = Math.random()*2 + 0.5;
  let aStep = Math.random() / 2 + 0.05;
  let r = 1;
  let angle = 0;
  let cx = w / 2;
  let cy = h / 2;
  for(let i = 0; i < 1500; i++) {
    let x = Math.cos(angle) * r;
    let y = Math.sin(angle) * r;
    pointList.push(new Vector(x + cx, y + cy));
    r += rStep;
    angle += aStep;
  }
  return pointList;
}

function bowyerWatson (superTriangle, pointList) {
  // pointList is a set of coordinates defining the 
  // points to be triangulated
  let triangulation = [];

  // add super-triangle to triangulation 
  // must be large enough to completely contain all 
  // the points in pointList
  triangulation.push(superTriangle);

  // add all the points one at a time to the triangulation
  pointList.forEach(point => {
    let badTriangles = [];
    
    // first find all the triangles that are no 
    // longer valid due to the insertion
    triangulation.forEach(triangle => { 
      if(triangle.pointIsInsideCircumcircle(point)) {
        badTriangles.push(triangle); 
      }
    });
    let polygon = [];
    
    // find the boundary of the polygonal hole
    badTriangles.forEach(triangle => {
      triangle.edges().forEach(edge => {
        let edgeIsShared = false;
        badTriangles.forEach(otherTriangle => {
          if(triangle !== otherTriangle &&  otherTriangle.hasEdge(edge)) {
            edgeIsShared = true;
          }
        });
        if(!edgeIsShared) {
          //edge is not shared by any other 
          // triangles in badTriangles
          polygon.push(edge);
        }
      });
    });
    
    // remove them from the data structure
    badTriangles.forEach(triangle => {
      let index = triangulation.indexOf(triangle);
      if (index > -1) {
        triangulation.splice(index, 1);
      }
    });
    
    // re-triangulate the polygonal hole
    polygon.forEach(edge => {
      //form a triangle from edge to point
      let newTri = new Triangle(edge[0], edge[1], point);
      triangulation.push(newTri);
    });
  });
  
  // done inserting points, now clean up
  let i = triangulation.length;
  while(i--) {
    let triangle = triangulation[i];
    if(triangle.sharesAVertexWith(superTriangle)) {
      //remove triangle from triangulation
      let index = triangulation.indexOf(triangle);
      if (index > -1) {
        triangulation.splice(index, 1);
      }
    }  
  }
  
  return triangulation;
}

function draw() {
  simplex = new SimplexNoise();
  zoom = Math.random() * 1000 + 400;
  
  ctx.fillStyle = "black";
  ctx.fillRect(0, 0, w, h);
  
  let superTriangle = new Triangle(
    new Vector(-w * 10, h * 10),
    new Vector(w * 10, h * 10),
    new Vector(w / 2, -h * 10)
  );
  
  let pointList = getRandomPoints();
  let triangles = bowyerWatson(superTriangle, pointList);
  triangles.forEach(t => t.draw());
}

setup();

              
            
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999px

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