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HTML 

              
                <div id="canvasContainer">
  <canvas id="canvas"></canvas>
</div>
!

CSS 

              
                body{
  margin:0;
}
#canvasContainer
{
  height:100%;
  width:100%;
  background:black;
}
#canvas
{
  margin:0;
  padding:0;
}
!

JS 

              
                var scriptActiveSlime = true;
var decay_slime = 0.1;
var sensor_slime = 4;
var abs_speed_slime = 3;
var angle_part_slime = 0.25;

(function(w) 
{
	///////////////////////////
	var numParticlesSlime = 5000;
	
	var diff = 0.5;

	var slime_part_shape = 0;
	
	var angle = angle_part_slime;
	
	////////////////////////////
	var theme = 0;
	var isMobileDevice = false;	
	var BACKGROUND_COLOR = 'rgba(0,0,0,0.1)';
	var color = '#238E9A';
	
	var PARTICLE_RADIUS = 0.3;
	var mousedown = false;
	var idcanvasSlime,
		canvasSlime,
		contextSlime,
		bufferCvs,
		bufferCtx,
		ww,
		wh,
	    offsetX,
	    offsetY,
		_particles = [];
	
	function toggleRenderShape()
	{
		if(slime_part_shape)
			slime_part_shape = 0;
		else
			slime_part_shape = 1;
		return slime_part_shape;
	}
	
	var V = function (x, y) { return new SAT.Vector(x, y); };
	
	function _Particles(x, y, radius, alfa, lambda)
	{
		this.pos = V(x,y);
		this.radius = radius;
		this.alfa = alfa;
		this.lambda = lambda;
		this.pheromone = 0;
		this._latest = V(0,0);
		this.setSpeed(abs_speed_slime);
	}
	
	_Particles.prototype = 
	{
		setSpeed:function(speed)
		{
			this._speed = V(Math.cos(this.alfa), Math.sin(this.alfa));
			this._speedL = V(Math.cos(this.alfa+this.lambda), Math.sin(this.alfa+this.lambda));
			this._speedR = V(Math.cos(this.alfa-this.lambda), Math.sin(this.alfa-this.lambda));
			this._speed.scale(speed);
			this._speedL.scale(speed);
			this._speedR.scale(speed);
		},
		update: function(dir) 
		{
			// Aggiorno direzione
			if (dir == 2)
				this.alfa -= this.lambda;			
			else if(dir==1)
				this.alfa += this.lambda;
			if(!dir == 0)
				this.setSpeed(abs_speed_slime);
			if(this.pos.x + this._speed.x < 0)
				this.pos.x+=ww;
			else if(this.pos.x + this._speed.x > ww)
				this.pos.x-=ww;
			else if(this.pos.y + this._speed.y < 0)
				this.pos.y+=wh;
			else if(this.pos.y + this._speed.y > wh)
				this.pos.y-=wh;
			// salvo vecchia posizione
			this._latest = this.pos.clone();			
			this.pos.add(this._speed);
		}
	};
	
	var gridPheromones = [];
	var resolution = 10000;
	var gridStep;
	var gridX = 0;
	var gridY = 0;
	var mouseWidth = 20;
	
	function initGrid()
	{
		gridStep = 1;
		for (var stepx = 0, i = 0; stepx < ww; stepx+=gridStep, i++)
		{
			gridPheromones[i] = [];
			gridX = i;
			for (var stepy = 0, j = 0; stepy < ww; stepy+=gridStep, j++)
			{
				gridPheromones[i][j] = 0;
				gridY = j;
			}
		}		
	}
	function decayGrid()
	{
		for (var stepx = 0, i = 0; stepx < ww; stepx+=gridStep, i++)
		{
			for (var stepy = 0, j = 0; stepy < ww; stepy+=gridStep, j++)
			{
				gridPheromones[i][j] = gridPheromones[i][j]*decay_slime;
			}
		}
	}
	function diffuseParticle(i, j, amount)
	{
		if(i<0 || j<0 || i >= ww || j >= wh) return;
		var left = (i-1 < 0) ? ww-1 : (i-1);
		var right = (i+1)%(ww-1);
		var up = (j-1 < 0) ? wh-1 : (j-1);
		var down = (j+1)%(wh-1);		
		gridPheromones[left][up] += diff*amount;
		gridPheromones[left][j] += diff*amount;
		gridPheromones[left][down] += diff*amount;
		gridPheromones[right][up] += diff*amount;
		gridPheromones[right][j] += diff*amount;
		gridPheromones[right][down] += diff*amount;
		gridPheromones[i][up] += diff*amount;
		gridPheromones[i][down] += diff*amount;
		gridPheromones[i][j] += amount;
	}
	
	// chiamare una volta prima dell'initScene
	function initcanvasSlime(id, style)
	{
		idContainerSlime = id+'Container';
		idcanvasSlime = id;
		canvasSlime  = document.getElementById(idcanvasSlime);
		bufferCvs = document.createElement('canvas');
		
		canvasSlime.addEventListener("mousedown", onMouseDown);
		canvasSlime.addEventListener("mousemove", onMouseMove);
		canvasSlime.addEventListener("touchmove", onTouchMove);
		canvasSlime.addEventListener("mouseup", onMouseUp);
		canvasSlime.addEventListener("mouseout", onMouseUp);
		
	}
	
	function onTouchMove(e)
	{
		if(!scriptActiveSlime) return;
		for (var i = -mouseWidth; i < mouseWidth; i++)
		{
			for (var j = -mouseWidth; j < mouseWidth; j++)
			{
				diffuseParticle(Math.floor(e.touches[0].clientX+i), Math.floor(e.touches[0].clientY+j), 10000000);
			}
		}
	}
	function onTouchDown(e)
	{
		if(!scriptActiveSlime) return;
		for (var i = -mouseWidth; i < mouseWidth; i++)
		{
			for (var j = -mouseWidth; j < mouseWidth; j++)
			{
				diffuseParticle(Math.floor(e.touches[0].clientX+i), Math.floor(e.touches[0].clientY+j), 10000000);
			}
		}
		
	}
	
	function onMouseDown(e)
	{
		if(!scriptActiveSlime) return;
		for (var i = -mouseWidth; i < mouseWidth; i++)
		{
			for (var j = -mouseWidth; j < mouseWidth; j++)
			{
				diffuseParticle(e.clientX+i-offsetX, e.clientY+j-offsetY, 10000000);
			}
		}
		mousedown = true;
	}
	function onMouseUp(){mousedown = false;}
	function onMouseMove(e)
	{
		if(!scriptActiveSlime) return;
		if (mousedown)
		{
			for (var i = -mouseWidth; i < mouseWidth; i++)
			{
				for (var j = -mouseWidth; j < mouseWidth; j++)
				{
					diffuseParticle(e.clientX+i-offsetX, e.clientY+j-offsetY, 10000000);
				}
			}
		}
			
	}
	
	function offsetsSlime(width, height)
	{
	    offsetX = Math.floor((window.innerWidth-width)*0.5);
	    offsetY = Math.floor((window.innerHeight-height)*0.5);
		ww = canvasSlime.width = width;
		wh = canvasSlime.height = height;
	
		bufferCvs.width = ww;
		bufferCvs.height = wh;
		contextSlime = canvasSlime.getContext('2d');
		bufferCtx = bufferCvs.getContext('2d');
	}
	
	function refreshSlime()
	{
		initSceneSlime(ww, wh);
	}
	
	
	
	// Init
	function initSceneSlime(width, height)
	{
		clearParticles();

		numParticles = numParticlesSlime;
		offsetsSlime(width, height);
		
		makeParticles(numParticlesSlime);
		initGrid();
	}
	 
	 // Functions
	
	function makeParticles(num) 
	{
		var i, p;
		for (i = 0; i < num; i++) 
		{
			p = new _Particles(
				Math.floor(ww*Math.random()),
				Math.floor(wh*Math.random()),
				PARTICLE_RADIUS,
				2*Math.PI*Math.random(),
				angle*Math.PI
			);
			_particles.push(p);
		}
	}
	
	function clearParticles()
	{
		_particles = [];
	}
	
	
	function findRoute(p)
	{
		var xs = Math.floor((p.pos.x + sensor_slime*p._speed.x)/gridStep)%gridX;
		if (xs<0) xs+= gridX;
		var ys = Math.floor((p.pos.y + sensor_slime*p._speed.y)/gridStep)%gridY;
		if (ys<0) ys+= gridY;
		
		var xl = Math.floor((p.pos.x + sensor_slime*p._speedL.x)/gridStep)%gridX;
		if (xl<0) xl+= gridX;
		var yl = Math.floor((p.pos.y + sensor_slime*p._speedL.y)/gridStep)%gridY;
		if (yl<0) yl+= gridY;
		
		var xr = Math.floor((p.pos.x + sensor_slime*p._speedR.x)/gridStep)%gridX;
		if (xr<0) xr+= gridX;
		var yr = Math.floor((p.pos.y + sensor_slime*p._speedR.y)/gridStep)%gridY;
		if (yr<0) yr+= gridY;
		
		var streight = gridPheromones[xs][ys];
		var left = gridPheromones[xl][yl];
		var right = gridPheromones[xr][yr];
		
		if (left == right)
		{
			if (!left >= streight) return 0; //dritto
			else return Math.floor(2*Math.random())+1;
		}
		else if (left > right)
		{
			if (left >= streight) return 1; //sx
			else return 0;
		}
		else
		{
			if (right >= streight) return 2; //dx
			else return 0;	
		}
	}
	
	function loopSlime() 
	{
		if(scriptActiveSlime)
		{
			if (angle_part_slime!=angle)
			{
				angle = angle_part_slime;
				refreshSlime();
			}
			var i, len, g, p;
			contextSlime.save();
			contextSlime.fillStyle = BACKGROUND_COLOR;
			contextSlime.fillRect(0, 0, ww, wh);
			contextSlime.restore();
			
			var rnd = Math.random();
			bufferCtx.save();
			bufferCtx.globalCompositeOperation = 'destination-out';
			bufferCtx.globalAlpha = 1; 
			bufferCtx.fillRect(0, 0, ww, wh);
			bufferCtx.restore();
			len = _particles.length;
			bufferCtx.save();
			bufferCtx.fillStyle = bufferCtx.strokeStyle = color;
			bufferCtx.lineCap = bufferCtx.lineJoin = 'round';
			bufferCtx.lineWidth = (slime_part_shape == 0) ? PARTICLE_RADIUS * (2 + rnd) : 3*PARTICLE_RADIUS * (2 + rnd);
			bufferCtx.beginPath();
			for (i = 0; i < len; i++) 
			{
				p = _particles[i];
				// decido dove andare
				var route = findRoute(p);
				// aggiorno la particella
				p.update(route);				
				bufferCtx.moveTo(p.pos.x, p.pos.y);
				if(slime_part_shape == 0)
				{
					bufferCtx.lineTo(p._latest.x, p._latest.y);
				}
				else if(slime_part_shape == 1)
				{
					bufferCtx.lineTo(p.pos.x, p.pos.y);
				}
				// aggiorno la griglia
				diffuseParticle(Math.floor((p.pos.x)/gridStep)%gridX,Math.floor((p.pos.y)/gridStep)%gridY, 1 /*+(p.pheromone*transport)*/);
			}
			bufferCtx.stroke();
			bufferCtx.restore();
			contextSlime.drawImage(bufferCvs, 0, 0);
			
			// dacay griglia
			decayGrid();
			
			if(numParticles!= numParticlesSlime)
			{
				initSceneSlime(ww, wh);
			}
			requestAnimationFrame(loopSlime);
		}
	}
	
	w.SlimeMold =
	{
		initCanvas : initcanvasSlime,
		init : initSceneSlime, 
		render : loopSlime,
		offset : offsetsSlime,
		refresh : refreshSlime,
		toggleRenderShape : toggleRenderShape
	}
	
}(window));

SlimeMold.initCanvas('canvas');
SlimeMold.init(window.innerWidth, window.innerHeight);
requestAnimationFrame(SlimeMold.render);
window.addEventListener('resize', resize);
function resize(){
  SlimeMold.init(window.innerWidth, window.innerHeight);
}
!
999px

Console