​

/*****************************************************************************

The MIT License (MIT)

​

Copyright (c) 2014 Andi Smithers

​

Permission is hereby granted, free of charge, to any person obtaining a copy

of this software and associated documentation files (the "Software"), to deal

in the Software without restriction, including without limitation the rights

to use, copy, modify, merge, publish, distribute, sublicense, and/or sell

copies of the Software, and to permit persons to whom the Software is

furnished to do so, subject to the following conditions:

​

The above copyright notice and this permission notice shall be included in

all copies or substantial portions of the Software.

​

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR

IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,

FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE

AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER

LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,

OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN

THE SOFTWARE.

*****************************************************************************/

​

// conceptualized and written by andi smithers

​

// constant options

const focalDepth = 80;

const focalPoint = 256;

​

​

// variables

var centreX;

var centreY;

var mouseX;

var mouseY;

var spawnX;

var spawnY;

var frameCount=0;

​

// variables

const maxpoints = 4096;

var pointcloud = [];

​

// uniform distribution of a randomized unit vector

function RandomNormal()

{

  var theta = Math.random() * Math.PI * 2;

  var nz = 1 - 2*Math.random();

  var phi = Math.acos(nz);

  var nx = Math.sin(theta)*Math.sin(phi);

  var ny = Math.cos(theta)*Math.sin(phi);

  return {x:nx, y:ny, z:nz};

}

​

function InitRandomDistribution()

{

   for (var i=0; i<maxpoints;i++)

   {

       pointcloud.push(RandomNormal());

   }

}

​

var theta = 0;

var phi = 0;

function RenderRandomDistribution()

{ 

    theta+=0.01;

    phi+=0.01;

    var scale = 20* canvas.height/500;

    context.beginPath();

    for (var i=0; i<pointcloud.length; i++)

    {

        var point = pointcloud[i];

        var x1 = point.x * Math.cos(theta) - point.z*Math.sin(theta);

        var z1 = point.x * Math.sin(theta) + point.z*Math.cos(theta);

        var y1 = point.y * Math.cos(phi) - z1*Math.sin(phi);

        var z1 = point.y * Math.sin(phi) + z1*Math.cos(phi);

        x1*=scale;

        z1*=scale;

        y1*=scale;

        if (z1+focalDepth<0) continue;

        var depth = focalPoint*3 / (z1 + focalDepth );

        var x = x1 * depth + centreX;

        var y = y1 * depth + centreY;

        var sz = depth * 0.2;

​

        // fill a rect

        context.rect(x,y, sz, sz);

    }

    context.fillStyle = '#ffffff';

    context.fill();

}

​

// initialization

​

function init()

{

  // setup canvas and context

canvas = document.getElementById('uniform distribution');

context = canvas.getContext('2d');

  // set canvas to be window dimensions

  resize();

​

  // create event listeners

  canvas.addEventListener('mousemove', mouseMove);

  canvas.addEventListener('click', mouseClick);

  window.addEventListener('resize', resize);

​

  // initialze variables  

  InitRandomDistribution();

}

​

​

// input functions

​

function mouseMove(event) 

{

var rect = canvas.getBoundingClientRect();

​

mouseX = event.clientX - rect.left,

mouseY = event.clientY - rect.top

}

​

function mouseClick()

{

}

​

function resize()

{

  canvas.width = window.innerWidth;

  canvas.height = window.innerHeight;

    // compute centre of screen

  centreX = canvas.width/2;

  centreY = canvas.height/2;

}

​

​

// rendering functions

​

function render()

{

  context.fillStyle = 'black';

  context.clearRect(0, 0, canvas.width, canvas.height); 

  RenderRandomDistribution();

  context.globalAlpha = 1.0;

  context.font = '20pt Calibri';

  context.fillStyle = 'rgb(255,255,0)';

  context.textAlign = "center";

  context.fillText('Random Normal', canvas.width/2, 25);

  context.fillText('Or randomized unit vector with a uniform distribution', canvas.width/2, 45);

  context.fillText('alternatively, even distribution of points on a the surface of a sphere', canvas.width/2, canvas.height-25);

​

}

​

// movement functions

​

function update()

{ 

}

​

// per frame tick functions

​

function animate()

{

  frameCount++;

  // movement update

  update();

  // render update

  render();

  // trigger next frame

  requestAnimationFrame(animate);

}

​

​

​

// entry point

init();

animate();</script>