如何更改此 javascript 动画在我网站上的位置？

Question

When I integrate this code into my website, It is placed at the bottom of the page under everything else. I have tried changing the css and html but cannot figure out why it does this.I want it to be placed in the header of my site. Is there any code in the javascript causing this? can anyone think of a reason this might be happening? thank you :)

https://jsfiddle.net/uz6yo2w3/

html

<script id="vertex-shader" type="no-js">
        void main() {
            gl_Position = vec4( position, 1.0 );
        }
</script>

<script id="fragment-shader" type="no-js">
#ifdef GL_ES
precision mediump float;
#endif

uniform float time;
uniform vec2 mouse;
uniform vec2 resolution;
varying vec2 surfacePosition;

const int NUM_STEPS = 8;
const float PI      = 3.1415;
const float EPSILON = 1e-3;
float EPSILON_NRM   = 0.1 / resolution.x;

// sea
const int ITER_GEOMETRY = 3;
const int ITER_FRAGMENT = 5;
const float SEA_HEIGHT = 0.6;
const float SEA_CHOPPY = 2.0;
const float SEA_SPEED = 0.8;
const float SEA_FREQ = 0.16;
const vec3 SEA_BASE = vec3(0.1,0.19,0.22);
const vec3 SEA_WATER_COLOR = vec3(0.8,0.9,0.6);
const float SKY_INTENSITY = 1.0;

#define SEA_TIME time * SEA_SPEED

// math
mat4 fromEuler(vec3 ang) {
  vec2 a1 = vec2(sin(ang.x),cos(ang.x));
    vec2 a2 = vec2(sin(ang.y),cos(ang.y));
    vec2 a3 = vec2(sin(ang.z),cos(ang.z));
    mat4 m;
    m[0] = vec4(a1.y*a3.y+a1.x*a2.x*a3.x,a1.y*a2.x*a3.x+a3.y*a1.x,-a2.y*a3.x,0.0);
    m[1] = vec4(-a2.y*a1.x,a1.y*a2.y,a2.x,0.0);
    m[2] = vec4(a3.y*a1.x*a2.x+a1.y*a3.x,a1.x*a3.x-a1.y*a3.y*a2.x,a2.y*a3.y,0.0);
    m[3] = vec4(0.0,0.0,0.0,1.0);
    return m;
}
vec3 rotate(vec3 v, mat4 m) {
    return vec3(dot(v,m[0].xyz),dot(v,m[1].xyz),dot(v,m[2].xyz));
}
float hash( vec2 p ) {
    float h = dot(p,vec2(127.1,311.7)); 
    return fract(sin(h)*43758.5453123);
}
float noise( in vec2 p ) {
    vec2 i = floor( p );
    vec2 f = fract( p );    
    vec2 u = f*f*(3.0-2.0*f);
    return -1.0+2.0*mix( mix( hash( i + vec2(0.0,0.0) ), 
                     hash( i + vec2(1.0,0.0) ), u.x),
                mix( hash( i + vec2(0.0,1.0) ), 
                     hash( i + vec2(1.0,1.0) ), u.x), u.y);
}


// lighting
float diffuse(vec3 n,vec3 l,float p) { return pow(dot(n,l) * 0.4 + 0.6,p); }
float specular(vec3 n,vec3 l,vec3 e,float s) {    
    float nrm = (s + 8.0) / (3.1415 * 8.0);
    return pow(max(dot(reflect(e,n),l),0.0),s) * nrm;
}

// sky
vec3 sky_color(vec3 e) {
    e.y = max(e.y,0.0);
    vec3 ret;
    ret.x = pow(1.0-e.y,2.0);
    ret.y = 1.0-e.y;
    ret.z = 0.6+(1.0-e.y)*0.4;
    return ret * SKY_INTENSITY;
}

// sea
float sea_octave(vec2 uv, float choppy) {
    uv += noise(uv);        
    vec2 wv = 1.0-abs(sin(uv));
    vec2 swv = abs(cos(uv));    
    wv = mix(wv,swv,wv);
    return pow(1.0-pow(wv.x * wv.y,0.65),choppy);
}

float map(vec3 p) {
    float freq = SEA_FREQ;
    float amp = SEA_HEIGHT;
    float choppy = SEA_CHOPPY;
    vec2 uv = p.xz; uv.x *= 0.75;
    mat2 m = mat2(1.6,1.2,-1.2,1.6);

    float d, h = 0.0;    
    for(int i = 0; i < ITER_GEOMETRY; i++) {        
        d = sea_octave((uv+SEA_TIME)*freq,choppy);
        d += sea_octave((uv-SEA_TIME)*freq,choppy);
        h += d * amp;        
        uv *= m; freq *= 1.9; amp *= 0.22;
        choppy = mix(choppy,1.0,0.2);
    }
    return p.y - h;
}
float map_detailed(vec3 p) {
    float freq = SEA_FREQ;
    float amp = SEA_HEIGHT;
    float choppy = SEA_CHOPPY;
    vec2 uv = p.xz; uv.x *= 0.75;
    mat2 m = mat2(1.6,1.2,-1.2,1.6);

    float d, h = 0.0;    
    for(int i = 0; i < ITER_FRAGMENT; i++) {        
        d = sea_octave((uv+SEA_TIME)*freq,choppy);
        d += sea_octave((uv-SEA_TIME)*freq,choppy);
        h += d * amp;        
        uv *= m; freq *= 1.9; amp *= 0.22;
        choppy = mix(choppy,1.0,0.2);
    }
    return p.y - h;
}

vec3 sea_color(in vec3 p, in vec3 n, in vec3 eye, in vec3 dist) {  
    float fresnel_o = 1.0 - max(dot(n,-eye),0.0);
    float fresnel = pow(fresnel_o,3.0) * 0.65;

    // reflection
    vec3 refl = sky_color(reflect(eye,n));

    // color
    vec3 ret = SEA_BASE;    
    ret = mix(ret,refl,fresnel);

    // wave peaks    
    float atten = max(1.0 - dot(dist,dist) * 0.001, 0.0);
    ret += SEA_WATER_COLOR * (p.y - SEA_HEIGHT) * 0.18 * atten;

    return ret;
}

// tracing
vec3 getNormal(vec3 p, float eps) {
    vec3 n;
    n.y = map_detailed(p);    
    n.x = map_detailed(vec3(p.x+eps,p.y,p.z)) - n.y;
    n.z = map_detailed(vec3(p.x,p.y,p.z+eps)) - n.y;
    n.y = eps;
    return normalize(n);
}
float hftracing(vec3 ori, vec3 dir, out vec3 p) {  
    float tm = 0.0;
    float tx = 1000.0;    
    float hx = map(ori + dir * tx);
    if(hx > 0.0) return tx;   
    float hm = map(ori + dir * tm);    
    float tmid = 0.0;
    for(int i = 0; i < NUM_STEPS; i++) {
        tmid = mix(tm,tx, hm/(hm-hx));                   
        p = ori + dir * tmid;                   
        float hmid = map(p);
    if(hmid < 0.0) {
            tx = tmid;
            hx = hmid;
        } else {
            tm = tmid;
            hm = hmid;
        }
    }
    return tmid;
}

// main
void main(void) 
{
  vec2 uv = gl_FragCoord.xy / resolution.xy;
  uv = 1.0 - uv * 2.0;
  uv.x *= resolution.x / resolution.y;   
  //uv = (surfacePosition+vec2(0., .5))*17. + 5E-3*(pow(length(surfacePosition+vec2(0. ,0.5)), -2.));
  uv.y *= -1.;
  //uv.y += -2.;

  // ray
  vec3 ang = vec3(0.0,0.003, pow(time, 0.6));
  ang = vec3(0.0,clamp(2.0-mouse.y*0.01,-0.3,PI),mouse.x*0.01);

  vec3 ori = vec3(0.0,3.5,time*.05);
  vec3 dir = normalize(vec3(uv.xy,-2.0));
  dir.z -= length(uv) * 0.15;
  //dir = rotate(normalize(dir),ang);

  // tracing
  vec3 p;
  float dens = hftracing(ori,dir,p);
  vec3 dist = p - ori;
  vec3 n = getNormal(p, dot(dist,dist)*EPSILON_NRM);

  // color
  vec3 color = sea_color(p,n,dir,dist);
  vec3 light = normalize(vec3(0.0,1.0,0.8));  
  color += vec3(diffuse(n,light,80.0) * SEA_WATER_COLOR) * 0.12; 
  color += vec3(specular(n,light,dir,60.0));  

  // post
  color = mix(sky_color(dir),color,pow(smoothstep(0.0,-0.05,dir.y),0.3)); 
  color = pow(color,vec3(0.75));
  gl_FragColor = vec4(color,1.0);
}
</script>

JS

// init camera, scene, renderer
var scene, camera, renderer;
scene = new THREE.Scene();
var fov = 75,
        aspect = window.innerWidth / window.innerHeight;
camera = new THREE.PerspectiveCamera(fov, aspect, 0.1, 1000);
camera.position.z = 100;
camera.lookAt(scene.position);
renderer = new THREE.WebGLRenderer();
renderer.setClearColor(0xc4c4c4);
renderer.setSize(window.innerWidth, window.innerHeight);
document.body.appendChild(renderer.domElement);
var clock = new THREE.Clock();

var tuniform = {
    time: {
        type: 'f',
        value: 0.1
    },
    resolution: {
        type: 'v2',
        value: new THREE.Vector2()
    },
    mouse: {
        type: 'v4',
        value: new THREE.Vector2()
    }
};

// Mouse position in - 1 to 1
renderer.domElement.addEventListener('mousedown', function(e) {
    var canvas = renderer.domElement;
    var rect = canvas.getBoundingClientRect();
    tuniform.mouse.value.x = (e.clientX - rect.left) / window.innerWidth * 2 - 1;
    tuniform.mouse.value.y = (e.clientY - rect.top) / window.innerHeight * -2 + 1; 
});
renderer.domElement.addEventListener('mouseup', function(e) {
    var canvas = renderer.domElement;
    var rect = canvas.getBoundingClientRect();
    tuniform.mouse.value.z = (e.clientX - rect.left) / window.innerWidth * 2 - 1;
    tuniform.mouse.value.w = (e.clientY - rect.top) / window.innerHeight * -2 + 1;
});
// resize canvas function
window.addEventListener('resize',function() {
    camera.aspect = window.innerWidth / window.innerHeight;
    camera.updateProjectionMatrix();
    renderer.setSize(window.innerWidth, window.innerHeight);
});

tuniform.resolution.value.x = window.innerWidth;
tuniform.resolution.value.y = window.innerHeight;
// Create Plane
var material = new THREE.ShaderMaterial({
    uniforms: tuniform,
    vertexShader: document.getElementById('vertex-shader').textContent,
    fragmentShader: document.getElementById('fragment-shader').textContent
});
var mesh = new THREE.Mesh(
    new THREE.PlaneBufferGeometry(window.innerWidth, window.innerHeight, 40), material
);
scene.add(mesh);

// draw animation
function render(time) {
    tuniform.time.value += clock.getDelta();
    requestAnimationFrame(render);
    renderer.render(scene, camera);
}
render();

Answer 1

This line:

document.body.appendChild(renderer.domElement);

That's what appends the canvas in the DOM, you can either store it in a reference and modify it's position

const animation = document.body.appendChild(renderer.domElement);
animation.css({
  'position': 'absolute',
  'top': 50,
  'left': 130,
});

or just append the canvas wherever you want to

document.getElementById('MyContainer').appendChild(renderer.domElement);

EDIT: ThreeJS works with WebGL, it's really heavy and will tank your site performance, if all you want is to have a sea animation look for a .gif in google, will work better