var mousePos = {x:.5,y:.5};
document.addEventListener('mousemove', function (event) {  mousePos = {x:event.clientX/window.innerWidth, y:event.clientY/window.innerHeight};});
var phase = 0;

var scene = new THREE.Scene();
var camera = new THREE.PerspectiveCamera(95, window.innerWidth / window.innerHeight, 0.1, 1000);
camera.position.z = 30;

var renderer = new THREE.WebGLRenderer();
renderer.setSize(window.innerWidth, window.innerHeight);
document.body.appendChild(renderer.domElement);

var boxSize = 0.2;
var geometry = new THREE.BoxGeometry(boxSize, boxSize, boxSize);
var materialGreen = new THREE.MeshBasicMaterial({transparent: true,  color: 0xff0000,  opacity: 0.4,  side: THREE.DoubleSide});

var pitchSegments = 60;
var elevationSegments = pitchSegments/2;
var particles = pitchSegments*elevationSegments
var side = Math.pow(particles, 1/3);

var radius = 16;

var parentContainer = new THREE.Object3D();
scene.add(parentContainer);

function posInBox(place) {
  return ((place/side) - 0.5) * radius * 1.2;  
}

//Plant the seeds, grow some trees in a grid!
for (var p = 0; p < pitchSegments; p++) {
  var pitch = Math.PI * 2 * p / pitchSegments ;
  for (var e = 0; e < elevationSegments; e++) {
    var elevation = Math.PI  * ((e / elevationSegments)-0.5)
    var particle = new THREE.Mesh(geometry, materialGreen);
    
    
    parentContainer.add(particle);

    var dest = new THREE.Vector3();
    dest.z = (Math.sin(pitch) * Math.cos(elevation)) * radius; //z pos in sphere
    dest.x = (Math.cos(pitch) * Math.cos(elevation)) * radius; //x pos in sphere
    dest.y = Math.sin(elevation) * radius; //y pos in sphere

    particle.position.x = posInBox(parentContainer.children.length % side);
    particle.position.y = posInBox(Math.floor(parentContainer.children.length/side) % side);
    particle.position.z = posInBox(Math.floor(parentContainer.children.length/Math.pow(side,2)) % side);
    console.log(side, parentContainer.children.length, particle.position.x, particle.position.y, particle.position.z)
    particle.userData = {dests: [dest,particle.position.clone()], speed: new THREE.Vector3() };
  }
}

function render() {
  phase += 0.002;
  for (var i = 0, l = parentContainer.children.length; i < l; i++) {
    var particle = parentContainer.children[i];
    var dest = particle.userData.dests[Math.floor(phase)%particle.userData.dests.length].clone();
    var diff = dest.sub(particle.position);
    particle.userData.speed.divideScalar(1.02); // Some drag on the speed
    particle.userData.speed.add(diff.divideScalar(400));// Modify speed by a fraction of the distance to the dest    
    particle.position.add(particle.userData.speed);
    particle.lookAt(dest);
  }
  
  parentContainer.rotation.y = phase*3;
  parentContainer.rotation.x = (mousePos.y-0.5) * Math.PI;
  parentContainer.rotation.z = (mousePos.x-0.5) * Math.PI;

  renderer.render(scene, camera);
  requestAnimationFrame(render);
}
render();