I am attempting to create a project similar to , but I am encountering issues with my system. Can someone assist me? Here is the link to my project: . I believe I may be incorrectly calculating the attraction between each particle.
The main problem lies in the fact that the particles have a single mass center and spin around it, instead of having a mass center that changes position.
<!DOCTYPE html>
<html>
<head>
<title>n-body</title>
<script src="http://mendow.github.io/projects/n-body/libs/three.js"></script>
<script src="http://mendow.github.io/projects/n-body/libs/OrbitControls.js"></script>
<script src="http://mendow.github.io/projects/n-body/libs/OBJLoader.js"></script>
<style>
body {
margin: 0;
overflow: hidden;
}
</style>
</head>
<script>
// define global variables
{
var renderer;
var scene;
var camera;
var orbit;
var ps;
var G = 9.81;
var dt = 0.0001;
var count = 1000;
var cam = 30;
}
function init() {
{
// create a scene to hold elements such as objects, cameras, and lights
scene = new THREE.Scene();
// create a camera to define the view
camera = new THREE.PerspectiveCamera(45, window.innerWidth / window.innerHeight, 0.1, 1000);
// create a renderer
renderer = new THREE.WebGLRenderer();
renderer.setClearColor(0x000000, 1.0);
renderer.setSize(window.innerWidth, window.innerHeight);
// position the camera
camera.position.x = cam;
camera.position.y = cam;
camera.position.z = cam;
camera.lookAt(scene.position);
orbit = new THREE.OrbitControls(camera);
}
setupParticleSystem(count);
// add renderer output to the html element
document.body.appendChild(renderer.domElement);
// render the scene
render();
}
function setupParticleSystem(y) {
var geometry = new THREE.Geometry();
for (var j = 0; j < y; j++) {
var v = new THREE.Vector3();
var ran = 30;
v.x = intRand(ran, -ran);
v.y = intRand(ran, -ran);
v.z = intRand(ran, -ran);
v.vel = new THREE.Vector3(intRand(1, -1), intRand(1, -1), intRand(1, -1));
v.acc = new THREE.Vector3(intRand(1, -1), intRand(1, -1), intRand(1, -1));
v.mass = intRand(5, 0);
geometry.vertices.push(v);
}
console.log(geometry.vertices);
var psMat = new THREE.PointCloudMaterial();
psMat.color = new THREE.Color(0x55ff55);
psMat.transparent = true;
psMat.size = 1;
psMat.blending = THREE.AdditiveBlending;
ps = new THREE.PointCloud(geometry, psMat);
ps.sizeAttenuation = true;
ps.sortParticles = true;
ps.position.y = 100 / cam;
ps.position.x = 100 / cam;
ps.position.z = 100 / cam;
scene.add(ps);
}
var step = 0;
function render() {
renderer.render(scene, camera);
requestAnimationFrame(render);
var r, mult;
var geometry = ps.geometry;
for (var i = 0; i < geometry.vertices.length; i++) {
for (var j = 0; j < geometry.vertices.length; j++) {
if (i != j) {
var particle = geometry.vertices[i];
var cntr = geometry.vertices[j];
r = particle.length(cntr);
mult = (-1) * G * (cntr.mass * particle.mass) / Math.pow(r, 3);
particle.acc.x = mult * particle.x;
particle.vel.x += particle.acc.x * dt;
particle.x += particle.vel.x * dt;
particle.acc.y = mult * particle.y;
particle.vel.y += particle.acc.y * dt;
particle.y += particle.vel.y * dt;
particle.acc.z = mult * particle.z;
particle.vel.z += particle.acc.z * dt;
particle.z += particle.vel.z * dt;
}
}
}
geometry.verticesNeedUpdate = true;
geometry.colorsNeedUpdate = true;
orbit.update();
}
window.onload = init;
function mrand() {
return Math.random();
}
function intRand(min, max) {
return Math.random() * (max - min) + min;
}
</script>
<body>
</body>
</html>