THREE.js Points on a tube

var scene = new THREE.Scene();
var width = window.innerWidth;
var height = window.innerHeight;
var camera = new THREE.PerspectiveCamera( 60, width / height, 1, 2100 );
scene.add(camera);
camera.position.set(0,100,500);
camera.lookAt(scene.position);
var canvas = document.createElement('canvas');
canvas.width = canvas.height = 4;
var context = canvas.getContext('2d');
context.lineWidth = 1;
context.fillStyle = 'rgba(255,255,0,1)';
context.fillRect( 0, 0, canvas.width, canvas.height );
context.strokeStyle = "rgba(255,0,0,1)";
context.strokeRect( 0, 0, canvas.width, canvas.height );
var texture = new THREE.Texture( canvas, THREE.UVMapping );
texture.needsUpdate = true;
var spriteMaterial = new THREE.SpriteMaterial({ map: texture });
var geometry = new THREE.PlaneGeometry( 1, 1 );
var meshMaterial = new THREE.MeshBasicMaterial({ map: texture });

function pointOnPath(p, q) {
    var lambda = Math.random();
    var scaledp = (new THREE.Vector3()).copy(p).multiplyScalar(1 - lambda);
    var scaledq = (new THREE.Vector3()).copy(q).multiplyScalar(lambda);
    var result = (new THREE.Vector3()).addVectors(scaledp, scaledq);
    return result;
}

function getVectorOffset(p, q, radius) {
    var v = (new THREE.Vector3()).subVectors(q, p);
    v.normalize();
    var e1 = new THREE.Vector3(v.y, -v.x, 0),
        e2 = new THREE.Vector3(v.z, 0, -v.x);
    e1.normalize();
    e2.normalize();

    var lambda = Math.random() - 0.5,
        mu = Math.random() - 0.5;
    var offset = e1.multiplyScalar(lambda).add(e2.multiplyScalar(mu));
    offset.normalize();
    offset.multiplyScalar(radius); // multiply the compute offset by the radius you'd like it to circle around

    return offset;

}

function pointOnHotDog(p, q, radius) {
    return pointOnPath(p, q).add(getVectorOffset(p, q, radius));
}

var p = new THREE.Vector3(100, 0, 10);
var q = new THREE.Vector3(250, 50, 0);
var radius = 300;
var particleGroup = new THREE.Object3D();
for( var i = 0; i < 300; i++ ) {
    var particle = new THREE.Sprite( spriteMaterial );
    particle.scale.set( 20, 20, 1 );

    spritePoint = pointOnHotDog(p, q, radius);
    var pX = spritePoint.x;
    var pY = spritePoint.y;
    var pZ = spritePoint.z;

    particle.position.set( pX, pY, pZ );
    particleGroup.add( particle );
}

particleGroup.position.y = 0;
scene.add( particleGroup );
camera.position.copy(p).sub(new THREE.Vector3(1000, 0, 0));
camera.lookAt(q);


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

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