body {
    margin: 0;
    overflow: hidden;
    width: 100vw;
    height: 100vh;
    background-image: url("https://user-images.githubusercontent.com/26748614/96337246-f14d4580-1085-11eb-8793-a86d929e034d.jpg");
    background-size: cover;
    backdrop-filter:  brightness(50%);
}

canvas {
    display: block;
}

#canvas_container {
    width: 100%;
    height: 100vh;
}

button {
    position: absolute;
    bottom: 5%;
    left: 50%;
    transform: translateX(-50%);
    border: 1px solid white;
    border-radius: 5px;
    font-size: 0.9rem;
    padding: 0.5rem 0.9em;
    background: #000000;
    color: white;
    -webkit-font-smoothing: antialiased;
    font-weight: bold;
    cursor: pointer;
    transition: all .3s;
}

button:hover {
    background: #ffffff;
    color: #000000;
}          

            let renderer,
scene,
camera,
sphereBg,
nucleus,
stars,
controls,
container = document.getElementById("canvas_container"),
timeout_Debounce,
noise = new SimplexNoise(),
cameraSpeed = 0,
blobScale = 3;


init();
animate();


function init() {
    scene = new THREE.Scene();

    camera = new THREE.PerspectiveCamera(55, window.innerWidth / window.innerHeight, 0.01, 1000)
    camera.position.set(0,0,230);

    const directionalLight = new THREE.DirectionalLight("#fff", 2);
    directionalLight.position.set(0, 50, -20);
    scene.add(directionalLight);

    let ambientLight = new THREE.AmbientLight("#ffffff", 1);
    ambientLight.position.set(0, 20, 20);
    scene.add(ambientLight);

    renderer = new THREE.WebGLRenderer({
        antialias: true,
        alpha: true
    });
    renderer.setSize(container.clientWidth, container.clientHeight);
    renderer.setPixelRatio(window.devicePixelRatio);
    container.appendChild(renderer.domElement);

    //OrbitControl
    controls = new THREE.OrbitControls(camera, renderer.domElement);
    controls.autoRotate = true;
    controls.autoRotateSpeed = 4;
    controls.maxDistance = 350;
    controls.minDistance = 150;
    controls.enablePan = false;

    const loader = new THREE.TextureLoader();
    const textureSphereBg = loader.load('https://i.ibb.co/4gHcRZD/bg3-je3ddz.jpg');
    const texturenucleus = loader.load('https://i.ibb.co/hcN2qXk/star-nc8wkw.jpg');
    const textureStar = loader.load("https://i.ibb.co/ZKsdYSz/p1-g3zb2a.png");
    const texture1 = loader.load("https://i.ibb.co/F8by6wW/p2-b3gnym.png");  
    const texture2 = loader.load("https://i.ibb.co/yYS2yx5/p3-ttfn70.png");
    const texture4 = loader.load("https://i.ibb.co/yWfKkHh/p4-avirap.png");


    /*  Nucleus  */   
    texturenucleus.anisotropy = 16;
    let icosahedronGeometry = new THREE.IcosahedronGeometry(30, 10);
    let lambertMaterial = new THREE.MeshPhongMaterial({ map: texturenucleus });
    nucleus = new THREE.Mesh(icosahedronGeometry, lambertMaterial);
    scene.add(nucleus);


    /*    Sphere  Background   */
    textureSphereBg.anisotropy = 16;
    let geometrySphereBg = new THREE.SphereBufferGeometry(150, 40, 40);
    let materialSphereBg = new THREE.MeshBasicMaterial({
        side: THREE.BackSide,
        map: textureSphereBg,
    });
    sphereBg = new THREE.Mesh(geometrySphereBg, materialSphereBg);
    scene.add(sphereBg);


    /*    Moving Stars   */
    let starsGeometry = new THREE.Geometry();

    for (let i = 0; i < 50; i++) {
        let particleStar = randomPointSphere(150); 

        particleStar.velocity = THREE.MathUtils.randInt(50, 200);

        particleStar.startX = particleStar.x;
        particleStar.startY = particleStar.y;
        particleStar.startZ = particleStar.z;

        starsGeometry.vertices.push(particleStar);
    }
    let starsMaterial = new THREE.PointsMaterial({
        size: 5,
        color: "#ffffff",
        transparent: true,
        opacity: 0.8,
        map: textureStar,
        blending: THREE.AdditiveBlending,
    });
    starsMaterial.depthWrite = false;  
    stars = new THREE.Points(starsGeometry, starsMaterial);
    scene.add(stars);


    /*    Fixed Stars   */
    function createStars(texture, size, total) {
        let pointGeometry = new THREE.Geometry();
        let pointMaterial = new THREE.PointsMaterial({
            size: size,
            map: texture,
            blending: THREE.AdditiveBlending,                      
        });

        for (let i = 0; i < total; i++) {
            let radius = THREE.MathUtils.randInt(149, 70); 
            let particles = randomPointSphere(radius);
            pointGeometry.vertices.push(particles);
        }
        return new THREE.Points(pointGeometry, pointMaterial);
    }
    scene.add(createStars(texture1, 15, 20));   
    scene.add(createStars(texture2, 5, 5));
    scene.add(createStars(texture4, 7, 5));


    function randomPointSphere (radius) {
        let theta = 2 * Math.PI * Math.random();
        let phi = Math.acos(2 * Math.random() - 1);
        let dx = 0 + (radius * Math.sin(phi) * Math.cos(theta));
        let dy = 0 + (radius * Math.sin(phi) * Math.sin(theta));
        let dz = 0 + (radius * Math.cos(phi));
        return new THREE.Vector3(dx, dy, dz);
    }
}


function animate() {

    //Stars  Animation
    stars.geometry.vertices.forEach(function (v) {
        v.x += (0 - v.x) / v.velocity;
        v.y += (0 - v.y) / v.velocity;
        v.z += (0 - v.z) / v.velocity;

        v.velocity -= 0.3;

        if (v.x <= 5 && v.x >= -5 && v.z <= 5 && v.z >= -5) {
            v.x = v.startX;
            v.y = v.startY;
            v.z = v.startZ;
            v.velocity = THREE.MathUtils.randInt(50, 300);
        }
    });


    //Nucleus Animation
    nucleus.geometry.vertices.forEach(function (v) {
        let time = Date.now();
        v.normalize();
        let distance = nucleus.geometry.parameters.radius + noise.noise3D(
            v.x + time * 0.0005,
            v.y + time * 0.0003,
            v.z + time * 0.0008
        ) * blobScale;
        v.multiplyScalar(distance);
    })
    nucleus.geometry.verticesNeedUpdate = true;
    nucleus.geometry.normalsNeedUpdate = true;
    nucleus.geometry.computeVertexNormals();
    nucleus.geometry.computeFaceNormals();
    nucleus.rotation.y += 0.002;


    //Sphere Beckground Animation
    sphereBg.rotation.x += 0.002;
    sphereBg.rotation.y += 0.002;
    sphereBg.rotation.z += 0.002;

    
    controls.update();
    stars.geometry.verticesNeedUpdate = true;
    renderer.render(scene, camera);
    requestAnimationFrame(animate);
}



/*     Resize     */
window.addEventListener("resize", () => {
    clearTimeout(timeout_Debounce);
    timeout_Debounce = setTimeout(onWindowResize, 80);
});
function onWindowResize() {
    camera.aspect = container.clientWidth / container.clientHeight;
    camera.updateProjectionMatrix();
    renderer.setSize(container.clientWidth, container.clientHeight);
}



/*     Fullscreen btn     */
// let fullscreen;
// let fsEnter = document.getElementById('fullscr');
// fsEnter.addEventListener('click', function (e) {
//     e.preventDefault();
//     if (!fullscreen) {
//         fullscreen = true;
//         document.documentElement.requestFullscreen();
//         fsEnter.innerHTML = "Exit Fullscreen";
//     }
//     else {
//         fullscreen = false;
//         document.exitFullscreen();
//         fsEnter.innerHTML = "Go Fullscreen";
//     }
// });