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 is required to process package imports. If you need a different preprocessor remove all packages first.

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

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.

Editor Settings

Code Indentation

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

Visit your global Editor Settings.

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.

HTML

            
              
            
          
!

CSS

            
              body {
  background: #333;
  overflow: hidden;
}
canvas {
  background: black;
}
            
          
!

JS

            
              var App = {};

jQuery(document).ready(function() {
  // Setup canvas and app
  App.setup();
  // Launch animation loop
  App.frame = function() {
    App.update();
    window.requestAnimationFrame(App.frame);
  };
	App.frame();
  
  jQuery('canvas#ourCanvas').on('click', function(event) {
    App.hasUserClicked = !App.hasUserClicked;
  });
  
  jQuery('canvas#ourCanvas').on('mousemove', function(event) {
    App.target.x = event.pageX;
    App.target.y = event.pageY;
  });
});

App.setup = function() {
  // Setup canvas and get canvas context
  var canvas = document.createElement('canvas');
  canvas.height = window.innerHeight;
  canvas.width = window.innerWidth;
  canvas.id = 'ourCanvas';
  document.body.appendChild(canvas);
  this.ctx = canvas.getContext('2d');
  this.width = canvas.width;
  this.height = canvas.height;
  
  // Define a few useful elements
  this.stepCount = 0;
  this.hasUserClicked = false;
  this.xC = canvas.width / 2;
  this.yC = canvas.height / 2;
  this.target = {
    x: this.xC,
    y: this.yC,
    radius: 20
  };
  this.armsPop = 20;
  //this.particlesPerArm = 15;
  
  // Create initial targets and arms
  this.arms = [];
  for (var i = 0; i < this.armsPop; i++) {
    this.arms.push([]);
  }
  // Fill initial arms
  this.initialBirth();
  
  // Some forces
  this.gravity = -1;
  this.springStiffness = 0.5;
  this.viscosity = 0.1;
  this.isElastic = false;
};
App.initialBirth = function() {
  for (var armIndex = 0; armIndex < this.arms.length; armIndex++) {
    var arm = this.arms[armIndex];
    // Random arm length! Sorta.
    var particlesNb = 20 + Math.ceil(20 * Math.random());
    for (var i = 0; i < particlesNb; i++) {
      var x = this.width * Math.random();
      var y = this.height * Math.random();
      var particle = {
        x: x,
        y: y,
        xLast: x,
        yLast: y,
        xSpeed: 0,
        ySpeed: 0,
        stickLength: 10,
        name: 'seed' + this.stepCount
      };

      arm.push(particle);
    }
  }
  
};
App.update = function() {
  // Evolve system
  this.evolve();
  // Move particles
  this.move();
  // Draw particles
  this.draw();
};
App.evolve = function() {
  this.stepCount++;
  this.target.radius = 50 + 30 * Math.sin(this.stepCount / 10);
};
App.move = function() {
  // This is inverse kinematics, the particles form an arm with N joints, and its shape adapts with a target contraint
  // Move target point
  if (!this.hasUserClicked) {
    this.target.x = this.xC + 150 * Math.cos(this.stepCount / 50);
    this.target.y = this.yC + 150 * Math.sin(this.stepCount / 20);
  }
  
  // Move particles accordingly (on each arm)
  for (var armIndex = 0; armIndex < this.arms.length; armIndex++) {
    var arm = this.arms[armIndex];
    var ownTargetAngle = 2 * Math.PI * armIndex / this.arms.length;
    var ownTarget = {
      x: this.target.x + this.target.radius * Math.cos(ownTargetAngle),
      y: this.target.y + this.target.radius * Math.sin(ownTargetAngle),
    }
    for (var i = 0; i < arm.length; i++) {
      var p = arm[i];
      // Leading particle (particle bound to head at first, then the preceding particle)
      var pLead = ( i == 0 ? ownTarget : arm[i-1] );
      var angle = segmentAngleRad(p.x, p.y, pLead.x, pLead.y, false);
      var dist = Math.sqrt(Math.pow(p.x - pLead.x, 2) + Math.pow(p.y - pLead.y, 2));
      var translationDist = dist - p.stickLength;
      if (translationDist < 0) {
        angle += Math.PI;
        translationDist = Math.abs(translationDist);
      }
      /* Kinetic binding */
      // Rotation, then translation for each particle/stick from head to tail
      var dx = translationDist * Math.cos(angle);
      var dy = translationDist * Math.sin(angle);
      if (!this.isElastic) {
        p.x += dx;
        p.y -= dy;
      }
      /* Forces */
      var xAcc = this.springStiffness * dx - this.viscosity * p.xSpeed;
      var yAcc = this.springStiffness * dy + this.gravity - this.viscosity * p.ySpeed;
      p.xSpeed += xAcc;
      p.ySpeed += yAcc;
      p.x += 0.1 * p.xSpeed;
      p.y -= 0.1 * p.ySpeed;
    }
  }
  
};
App.draw = function() {
  // Add transparent layer for trace effect
  this.ctx.beginPath();
  this.ctx.rect(0, 0, this.width, this.height);
  this.ctx.fillStyle = 'rgba(0, 0, 0, 0.3)';
  this.ctx.fill();
  
  // Draw target
  this.ctx.beginPath();
  this.ctx.arc(this.target.x, this.target.y, 15, 0, 2 * Math.PI, false);
  this.ctx.fillStyle = 'rgba(255, 255, 255, 0.1)';
  this.ctx.fill();
  
  // Draw particles
  for (var armIndex = 0; armIndex < this.arms.length; armIndex++) {
    var arm = this.arms[armIndex];
    for (var i = 0; i < arm.length; i++) {
      var particle = arm[i];
      if (i != 0) { var particleLead = arm[i-1]; }

      // Draw particle
      this.ctx.beginPath();
      this.ctx.arc(particle.x, particle.y, 0.3 * (arm.length - i), 0, 2 * Math.PI, false);
      this.ctx.strokeStyle = 'hsla(' + (200 + i * 4) + ', 90%, 50%, 0.7)';
      this.ctx.stroke();
      // Draw its stick
      this.ctx.beginPath();
      this.ctx.lineWidth = 1;
      this.ctx.strokeStyle = 'hsla(' + (180 + i * 4) + ', 80%, 50%, 0.7)';
      if (i == 0) this.ctx.moveTo(this.target.x, this.target.y);
      else this.ctx.moveTo(particleLead.x, particleLead.y);
      this.ctx.lineTo(particle.x, particle.y);
      this.ctx.stroke();

    }
  }
};



/**
 * @param {Number} Xstart X value of the segment starting point
 * @param {Number} Ystart Y value of the segment starting point
 * @param {Number} Xtarget X value of the segment target point
 * @param {Number} Ytarget Y value of the segment target point
 * @param {Boolean} realOrWeb true if Real (Y towards top), false if Web (Y towards bottom)
 * @returns {Number} Angle between 0 and 2PI
 */
segmentAngleRad = function(Xstart, Ystart, Xtarget, Ytarget, realOrWeb) {
	var result;// Will range between 0 and 2PI
	if (Xstart == Xtarget) {
		if (Ystart == Ytarget) {
			result = 0; 
		} else if (Ystart < Ytarget) {
			result = Math.PI/2;
		} else if (Ystart > Ytarget) {
			result = 3*Math.PI/2;
		} else {}
	} else if (Xstart < Xtarget) {
		result = Math.atan((Ytarget - Ystart)/(Xtarget - Xstart));
	} else if (Xstart > Xtarget) {
		result = Math.PI + Math.atan((Ytarget - Ystart)/(Xtarget - Xstart));
	}
	
	result = (result + 2*Math.PI)%(2*Math.PI);
	
	if (!realOrWeb) {
		result = 2*Math.PI - result;
	}
	
	return result;
}

            
          
!
999px

Console