マウス移動に反応する球体のページ背景

/**
 * ボールSVG画像出力
 *
 * @author ao-system, Inc.
 * @date 2024-02-02
 */

export class BallImage {
	'use strict';
	#place;
	#color = ['rgba(255,50,255,1)','rgba(50,50,255,1)'];
	#filter = 'blur(1px) drop-shadow(0 0 40px #ff0)';
	#svgElm;
	#svgPath;
	constructor(param) {
		if (param.place) {
			this.#place = param.place;
		}
		if (param.color) {
			this.#color = param.color;
		}
		if (param.filter) {
			this.#filter = param.filter;
		}
		this.#init();
	}
	set place(val) {
		if (this.#place instanceof Element) {
			this.#place.innerHTML = '';
		}
		this.#place = val;
		this.#createSvg();
	}
	set color(val) {
		if (this.#place instanceof Element) {
			this.#place.innerHTML = '';
		}
		this.#color = val;
		this.#createSvg();
	}
	set filter(val) {
		if (this.#place instanceof Element) {
			this.#place.innerHTML = '';
		}
		this.#filter = val;
		this.#createSvg();
	}
	#init() {
		this.#createSvg();
		document.addEventListener('mousemove', (event) => this.#handleMouseMove(event));
		this.#handleMouseMove({clientX:0,clientY:0});
	}
	//<svg version="1.1" xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" width="200px" height="200px" viewBox="0 0 200 200">
	//	<radialGradient id="rg" cx="100" cy="100" r="50%" gradientUnits="userSpaceOnUse">
	//		<stop offset="0" style="stop-color:#7f6"/>
	//		<stop offset="1" style="stop-color:#ff9"/>
	//	</radialGradient>
	//	<path fill="url(#rg)" d="M150,100C150,127,127,150,100,150S50,127,50,100S72,50,100,50S150,72,150,100z"/>
	//</svg>
	#createSvg() {
		const radialGradientId = this.#generateRandomId();
		this.#svgElm = document.createElementNS('http://www.w3.org/2000/svg','svg');
		this.#svgElm.setAttribute('xmlns','http://www.w3.org/2000/svg');
		//this.#svgElm.setAttribute('width','200px');
		//this.#svgElm.setAttribute('height','200px');
		this.#svgElm.setAttribute('viewBox','0 0 200 200');
		this.#svgElm.style.filter = this.#filter;
		const radialGradient = document.createElementNS('http://www.w3.org/2000/svg','radialGradient');
		radialGradient.setAttribute('id',radialGradientId);
		radialGradient.setAttribute('cx',100);
		radialGradient.setAttribute('cy',100);
		radialGradient.setAttribute('r','40%');
		radialGradient.setAttribute('gradientUnits','userSpaceOnUse');
		const stop1 = document.createElementNS('http://www.w3.org/2000/svg','stop');
		stop1.setAttribute('offset',0);
		stop1.setAttribute('style','stop-color:' + this.#color[0]);
		const stop2 = document.createElementNS('http://www.w3.org/2000/svg','stop');
		stop2.setAttribute('offset',1);
		stop2.setAttribute('style','stop-color:' + this.#color[1]);
		this.#svgPath = document.createElementNS('http://www.w3.org/2000/svg','path');
		this.#svgPath.setAttribute('fill','url(#' + radialGradientId + ')');
		radialGradient.appendChild(stop1);
		radialGradient.appendChild(stop2);
		this.#svgElm.appendChild(radialGradient);
		this.#svgElm.appendChild(this.#svgPath);
		this.#place?.appendChild(this.#svgElm);
	}
	#generateRandomId(idLength = 12) {
		const characters = 'abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ';
		return Array.from({length:idLength}, () => characters[Math.floor(Math.random() * characters.length)]).join('');
	}
	#handleMouseMove(event) {
		const ratioX = event.clientX / window.innerWidth;
		const ratioY = (event.clientY + window.scrollY) / window.innerHeight;
		const ratio = 100;
		const x1 = Math.max(0,(ratioX - 0.6) * ratio);
		const y1 = (ratioY - 0.5) * ratio;
		const x2 = (ratioX - 0.5) * ratio;
		const y2 = Math.max(0,(ratioY - 0.6) * ratio);
		const x3 = Math.min(0,(ratioX - 0.4) * ratio);
		const y3 = (ratioY - 0.5) * ratio;
		const x4 = (ratioX - 0.5) * ratio;
		const y4 = Math.min(0,(ratioY - 0.4) * ratio);
		const d = [
			`M${150 + x1},${100 + y1}C${150 + x1},${127 + y1},${127 + x2},${150 + y2},${100 + x2},${150 + y2}`,
			`S${50 + x3},${127 + y3},${50 + x3},${100 + y3}`,
			`S${72 + x4},${50 + y4},${100 + x4},${50 + y4}`,
			`S${150 + x1},${72 + y1},${150 + x1},${100 + y1}`,
			`z`,
		].join('');
		this.#svgPath.setAttribute('d',d);
	}
}