js实现canvas光源跟随鼠标交互照射方块盒子影子效果代码-html代码-BFW代码库

代码语言：html

所属分类：动画

代码描述：js实现canvas光源跟随鼠标交互照射方块盒子影子效果代码

下面为部分代码预览，完整代码请点击下载或在bfwstudio webide中打开

<!DOCTYPE html>
<html lang="en" >

<head>
  <meta charset="UTF-8">
  

  
  
  
<style>
#canvas1 {
  width: 100%;
  height: 100%;
  outline: 2px slateblue solid;
  margin: auto;
  cursor: none;
}

body {
  background: linear-gradient(129deg, #3f5efb 0%, #fc466b 100%);
}

/* ~~~~~ IGNORE... Mini CSS-Reset + Placement ~~~~~~ */
*,
*::before,
*::after {
  padding: 0;
  margin: 0 auto;
  box-sizing: border-box;
  font-family: inherit;
}

html,
body {
  width: 100%;
  height: 100%;
}

body {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  min-height: 100vh;
}
</style>

  
  
</head>

<body>
  <canvas id="canvas1"></canvas>
  
      <script >
/** @type {HTMLCanvasElement} **/
const canv = document.getElementById("canvas1");
const ctx = canv.getContext("2d");
const BOX_CORNER_ANGLE = (2 * Math.PI) / 4; // == 90°*(π/180) == (2*π)/4 == 90deg in rad

const NUM_BOXES = 20; // Nice if it can be 360 % ___ === 0

const SHADOW_COLOR = "#00000030"; // Some opacity for overlay effect
const SHADOW_LENGTH = 2000; // Arbitrary Large #

const BASE_HUE = Math.floor(Math.random() * 360);
const HUE_ROTATION = Math.floor(360 / NUM_BOXES);
// const canvasFillColor = window.getComputedStyle(canv).backgroundColor;

let boxesArr = [];
const light = { x: 0, y: 0 }; // is set to Canvas' center in init()

const updateCanvasSize = () => {
  const canv = document.getElementById("canvas1");
  const boundingRect = canv.getBoundingClientRect();
  canv.width = boundingRect.width;
  canv.height = boundingRect.height;
  canvasStartX = boundingRect.x;
  canvasStartY = boundingRect.y;
};

const generateHslColorString = (i) => {
  let hue = BASE_HUE + i * HUE_ROTATION;
  if (hue > 360) {
    hue = Math.floor(hue % 360);
  }

  const saturation = Math.floor(Math.random() * 60) + 40; // between 40 - 100
  return `hsl(${hue}, ${saturation}%, 50%)`;
};

function Box(color) {
  this.size = Math.floor(Math.random() * 20 + 10); // between 10 + 30
  this.x = Math.floor(Math.random() * (canv.width - this.size) + 1); // initial random placement
  this.y = Math.floor(Math.random() * (canv.height - this.size) + 1); // initial random placement
  this.velocity = (60 - this.size) / 40; // 🤷‍♂️ (why not?)
  this.r = Math.random() * Math.PI;
  this.color = color;
  this.directionY = Math.random() < 0.5 ? -1 : 1; //  -1 or +1
  this.directionX = Math.random() < 0.5 ? -1 : 1; //  -1 or +1
  this.directionR = Math.random() < 0.5 ? -1 : 1; //  -1 (clockwise) or +1 (counter-clockwise)

  this.generateBoxCoords = function () {
    const p1 = {
      x: this.x + this.size * Math.sin(this.r),
      y: this.y + this.size * Math.cos(this.r)
    };
    const p2 = {
      x: this.x + this.size * Math.sin(this.r + BOX_CORNER_ANGLE),
      y: this.y + this.size * Math.cos(this.r + BOX_CORNER_ANGLE)
    };
    const p3 = {
      x: this.x + this.size * Math.sin(this.r + BOX_CORNER_ANGLE * 2),
      y: this.y + this.size * Math.cos(this.r + BOX_CORNER_ANGLE * 2)
    };
    const p4 = {
      x: this.x + this.size * Math.sin(this.r + BOX_CORNER_ANGLE * 3),
      y: this.y + this.size * Math.cos(this.r + BOX_CORNER_ANGLE * 3)
    };

    return { p1, p2, p3, p4 };
  };
  this.rotate = function () {
    this.r += this.directionR * this.velocity * 0.01;
    this.x += this.directionX * this.velocity;
    this.y += this.directionY * this.velocity;
  };
  this.draw = function () {
    ctx.save();
    const points = this.generateBoxCoords();
    ctx.beginPath();
    ctx.moveTo(points.p1.x, points.p1.y);
    ctx.lineTo(points.p2.x, points.p2.y);
    ctx.lineTo(points.p3.x, points.p3.y);
    ctx.lineTo(points.p4.x, points.p4.y);
    ctx?.closePath();

    ctx.globalAlpha = 0.8; // Some opacity for boxes overlapping
    ctx.fillStyle = this.color;
    ctx.fill();
    ctx?.stroke();
    ctx.restore();
  };
  this.drawShadow = function () {
    const coords = this.generateBoxCoords();
    var pointsArr = [];
    // var angles = []; ???

    for (point in coords) {
      const angle =
        Math.atan2(light.y - coords[point].y, light.x - coords[point].x) * -1;
      // angles.push(angle); ???
      pointsArr.push({
        startX: coords[point].x,
        startY: coords[point].y,
      .........完整代码请登录后点击上方下载按钮下载查看