Add starfield.js in the landing page. (#1833)

docs/index.html

@@ -1,7 +1,10 @@
 <!-- Section: hero -->
 <section data-md-color-scheme="slate" data-md-color-primary="grey" class="home-div" style="height: min(100vh, 120vw); position: relative; margin-top:-2.4rem; padding: 0; overflow: hidden;">
     <!-- hero image -->
-    <img src="assets/hero/universe_bg.png" class="hero-bg" alt="">
+    <!-- <img alt="" class="hero-bg" src="assets/hero/universe_bg.png" /> -->
+    <div class="starfield">
+        <div class="starfield-origin"></div>
+    </div>
     <div class="hero-div">
         <img src="assets/hero/ground.png" alt="" style="position: absolute; width: auto; height: 26.445%; left: 28.211%; top: 54.145%;">
         <img src="assets/hero/links.png" alt="" style="position: absolute; width: auto; height: 78.751%; left: 10.545%; top: 7.326%;">

en/docs/index.html

@@ -1,7 +1,10 @@
 <!-- Section: hero -->
 <section data-md-color-scheme="slate" data-md-color-primary="grey" class="home-div" style="height: min(100vh, 120vw); position: relative; margin-top:-2.4rem; padding: 0; overflow: hidden;">
     <!-- hero image -->
-    <img src="../assets/hero/universe_bg.png" class="hero-bg" alt="">
+    <!-- <img alt="" class="hero-bg" src="assets/hero/universe_bg.png" /> -->
+    <div class="starfield">
+        <div class="starfield-origin"></div>
+    </div>
     <div class="hero-div">
         <img src="../assets/hero/ground.png" alt="" style="position: absolute; width: auto; height: 26.445%; left: 28.211%; top: 54.145%;">
         <img src="../assets/hero/links.png" alt="" style="position: absolute; width: auto; height: 78.751%; left: 10.545%; top: 7.326%;">

ja/docs/index.html

@@ -1,7 +1,10 @@
 <!-- Section: hero -->
 <section data-md-color-scheme="slate" data-md-color-primary="grey" class="home-div" style="height: min(100vh, 120vw); position: relative; margin-top:-2.4rem; padding: 0; overflow: hidden;">
     <!-- hero image -->
-    <img src="../assets/hero/universe_bg.png" class="hero-bg" alt="">
+    <!-- <img alt="" class="hero-bg" src="assets/hero/universe_bg.png" /> -->
+    <div class="starfield">
+        <div class="starfield-origin"></div>
+    </div>
     <div class="hero-div">
         <img src="../assets/hero/ground.png" alt="" style="position: absolute; width: auto; height: 26.445%; left: 28.211%; top: 54.145%;">
         <img src="../assets/hero/links.png" alt="" style="position: absolute; width: auto; height: 78.751%; left: 10.545%; top: 7.326%;">

overrides/javascripts/starfield.js

@@ -0,0 +1,471 @@
+/*
+ * starfield.js
+ *
+ * Version: 1.5.0
+ * Description: Interactive starfield background
+ *
+ * Usage:
+ *  Starfield.setup({
+ *    // options
+ *  });
+ */
+(function (root, factory) {
+  if (typeof define === "function" && define.amd) {
+    define([], factory);
+  } else if (typeof module === "object" && module.exports) {
+    module.exports = factory();
+  } else {
+    root.Starfield = factory();
+  }
+})(this, function () {
+  const Starfield = {};
+
+  const config = {
+    numStars: 250, // Number of stars
+    baseSpeed: 1, // Base speed of stars (will affect acceleration)
+    trailLength: 0.8, // Length of star trail (0-1)
+    starColor: "rgb(255, 255, 255)", // Color of stars (only rgb)
+    canvasColor: "rgb(0, 0, 0)", // Canvas background color (only rgb)
+    hueJitter: 0, // Maximum hue variation in degrees (0-360)
+    maxAcceleration: 10, // Maximum acceleration
+    accelerationRate: 0.2, // Rate of acceleration
+    decelerationRate: 0.2, // Rate of deceleration
+    minSpawnRadius: 80, // Minimum spawn distance from origin
+    maxSpawnRadius: 500, // Maximum spawn distance from origin
+    auto: true,
+    originX: null,
+    originY: null,
+    container: null,
+    originElement: null,
+  };
+
+  let stars = [];
+  let accelerate = false;
+  let accelerationFactor = 0;
+  let originX = 0;
+  let originY = 0;
+  let prevOriginX = 0;
+  let prevOriginY = 0;
+
+  let canvas, ctx;
+  let width, height;
+  let lastTimestamp = 0;
+  let canvasRGB = [0, 0, 0];
+  let lastCanvasColor = config.canvasColor;
+
+  let origin;
+  let container;
+
+  const mouseEnterHandler = () => (accelerate = true);
+  const mouseLeaveHandler = () => (accelerate = false);
+  const resizeHandler = () => windowResized(container, origin);
+
+  function visibilityHandler() {
+    if (document.visibilityState === "visible") {
+      lastTimestamp = performance.now();
+    }
+  }
+
+  function getOriginY(origin, container) {
+    const originRect = origin.getBoundingClientRect();
+    const containerRect = container.getBoundingClientRect();
+    return originRect.top - containerRect.top + originRect.height / 2;
+  }
+
+  function getOriginX(origin, container) {
+    const originRect = origin.getBoundingClientRect();
+    const containerRect = container.getBoundingClientRect();
+    return originRect.left - containerRect.left + originRect.width / 2;
+  }
+
+  /**
+   * Set up and start the starfield animation.
+   * @param {Object} userConfig Configuration options.
+   */
+  function setup(userConfig = {}) {
+    Object.assign(config, userConfig);
+
+    container = config.container || document.querySelector(".starfield");
+    if (!container) {
+      throw new Error("Starfield: No container element found.");
+    }
+    // container.style.position = "relative";
+
+    width = container.clientWidth;
+    height = container.clientHeight;
+
+    canvas = document.createElement("canvas");
+    canvas.width = width;
+    canvas.height = height;
+
+    canvas.style.position = "absolute";
+    canvas.style.top = "0";
+    canvas.style.left = "0";
+    canvas.style.width = "100%";
+    canvas.style.height = "100%";
+    canvas.style.zIndex = "-1";
+    canvasRGB = parseRGBA(config.canvasColor);
+
+    container.appendChild(canvas);
+
+    ctx = canvas.getContext("2d");
+
+    if (config.auto) {
+      origin =
+        config.originElement || document.querySelector(".starfield-origin");
+      if (!origin) {
+        throw new Error("Starfield: No origin element found.");
+      }
+      originX = getOriginX(origin, container);
+      originY = getOriginY(origin, container);
+
+      origin.addEventListener("mouseenter", mouseEnterHandler);
+      origin.addEventListener("mouseleave", mouseLeaveHandler);
+
+      window.addEventListener("resize", resizeHandler);
+    } else {
+      originX = config.originX !== null ? config.originX : width / 2;
+      originY = config.originY !== null ? config.originY : height / 2;
+    }
+
+    for (let i = 0; i < config.numStars; i++) {
+      const star = createRandomStar();
+      stars.push(star);
+    }
+
+    document.addEventListener("visibilitychange", visibilityHandler);
+
+    requestAnimationFrame(draw);
+  }
+
+  function windowResized(container, origin) {
+    width = container.clientWidth;
+    height = container.clientHeight;
+    canvas.width = width;
+    canvas.height = height;
+
+    originX = getOriginX(origin, container);
+    originY = getOriginY(origin, container);
+
+    stars.forEach((star) => star.reset());
+  }
+
+  function createRandomStar() {
+    const angle = random(0, Math.PI * 2);
+    const radius = random(config.minSpawnRadius, config.maxSpawnRadius);
+
+    const x = originX + Math.cos(angle) * radius;
+    const y = originY + Math.sin(angle) * radius;
+
+    return new Star(x, y);
+  }
+
+  class Star {
+    constructor(x, y) {
+      this.pos = {
+        x: x,
+        y: y,
+      };
+      this.prevpos = {
+        x: x,
+        y: y,
+      };
+      this.vel = {
+        x: 0,
+        y: 0,
+      };
+      this.angle = Math.atan2(y - originY, x - originX);
+      this.baseSpeed = random(config.baseSpeed * 0.5, config.baseSpeed * 1.5);
+      this.hueOffset = random(-config.hueJitter, config.hueJitter);
+    }
+
+    reset() {
+      const newStar = createRandomStar();
+      this.pos.x = newStar.pos.x;
+      this.pos.y = newStar.pos.y;
+      this.prevpos.x = this.pos.x;
+      this.prevpos.y = this.pos.y;
+      this.vel.x = 0;
+      this.vel.y = 0;
+      this.angle = Math.atan2(this.pos.y - originY, this.pos.x - originX);
+      this.baseSpeed = random(config.baseSpeed * 0.5, config.baseSpeed * 1.5);
+      this.hueOffset = random(-config.hueJitter, config.hueJitter);
+    }
+
+    update(acc, deltaTime) {
+      const adjustedAcc = acc * this.baseSpeed;
+
+      this.vel.x += Math.cos(this.angle) * adjustedAcc * deltaTime;
+      this.vel.y += Math.sin(this.angle) * adjustedAcc * deltaTime;
+
+      this.prevpos.x = this.pos.x;
+      this.prevpos.y = this.pos.y;
+      this.pos.x += this.vel.x * deltaTime;
+      this.pos.y += this.vel.y * deltaTime;
+    }
+
+    draw() {
+      let velMag = Math.sqrt(
+        this.vel.x * this.vel.x + this.vel.y * this.vel.y
+      );
+      velMag = velMag * 3;
+      const alpha = map(velMag, 0, 10, 0, 1);
+      const weight = map(velMag, 0, 10, 1, 3);
+
+      ctx.lineWidth = weight;
+
+      const [r, g, b] = parseRGBA(config.starColor);
+      const [h, s, l] = rgbToHsl(r, g, b);
+      const adjustedH = (h + this.hueOffset + 360) % 360;
+      const [newR, newG, newB] = hslToRgb(adjustedH, s, l).map((v) =>
+        Math.round(v)
+      );
+      ctx.strokeStyle = `rgba(${newR}, ${newG}, ${newB}, ${alpha})`;
+
+      ctx.beginPath();
+      ctx.moveTo(this.prevpos.x, this.prevpos.y);
+      ctx.lineTo(this.pos.x, this.pos.y);
+      ctx.stroke();
+    }
+
+    isActive() {
+      return onScreen(this.pos.x, this.pos.y);
+    }
+
+    updateAngle() {
+      this.angle = Math.atan2(this.pos.y - originY, this.pos.x - originX);
+    }
+  }
+
+  function draw(timestamp) {
+    if (!lastTimestamp) lastTimestamp = timestamp;
+    const deltaTime = (timestamp - lastTimestamp) / 16.67;
+    lastTimestamp = timestamp;
+
+    if (config.auto) {
+      originX = getOriginX(origin, container);
+      originY = getOriginY(origin, container);
+      if (originX !== prevOriginX || originY !== prevOriginY) {
+        stars.forEach((star) => {
+          star.updateAngle();
+        });
+        prevOriginX = originX;
+        prevOriginY = originY;
+      }
+    }
+
+    if (lastCanvasColor !== config.canvasColor) {
+      canvasRGB = parseRGBA(config.canvasColor);
+      lastCanvasColor = config.canvasColor;
+    }
+    const [bgR, bgG, bgB] = canvasRGB;
+    ctx.fillStyle = `rgba(${bgR}, ${bgG}, ${bgB}, ${1 - config.trailLength})`;
+    ctx.fillRect(0, 0, width, height);
+
+    if (accelerate) {
+      accelerationFactor = Math.min(
+        accelerationFactor + config.accelerationRate * deltaTime,
+        config.maxAcceleration
+      );
+    } else {
+      accelerationFactor = Math.max(
+        accelerationFactor - config.decelerationRate * deltaTime,
+        0
+      );
+    }
+
+    const baseAcc = 0.01;
+    const currentAcc = baseAcc * (1 + accelerationFactor * 10);
+
+    for (let star of stars) {
+      star.update(currentAcc, deltaTime);
+      star.draw();
+      if (!star.isActive()) {
+        star.reset();
+      }
+    }
+
+    requestAnimationFrame(draw);
+  }
+
+  function onScreen(x, y) {
+    return x >= 0 && x <= width && y >= 0 && y <= height;
+  }
+
+  function random(min, max) {
+    return Math.random() * (max - min) + min;
+  }
+
+  // https://gist.github.com/mjackson/5311256
+  function rgbToHsl(r, g, b) {
+    r /= 255;
+    g /= 255;
+    b /= 255;
+    const max = Math.max(r, g, b),
+      min = Math.min(r, g, b);
+    let h,
+      s,
+      l = (max + min) / 2;
+
+    if (max === min) {
+      h = s = 0;
+    } else {
+      const d = max - min;
+      s = l > 0.5 ? d / (2 - max - min) : d / (max + min);
+      switch (max) {
+        case r:
+          h = (g - b) / d + (g < b ? 6 : 0);
+          break;
+        case g:
+          h = (b - r) / d + 2;
+          break;
+        case b:
+          h = (r - g) / d + 4;
+          break;
+      }
+      h /= 6;
+    }
+
+    return [h * 360, s, l];
+  }
+
+  // https://gist.github.com/mjackson/5311256
+  function hslToRgb(h, s, l) {
+    let r, g, b;
+    h = h / 360;
+
+    if (s === 0) {
+      r = g = b = l;
+    } else {
+      const hue2rgb = (p, q, t) => {
+        if (t < 0) t += 1;
+        if (t > 1) t -= 1;
+        if (t < 1 / 6) return p + (q - p) * 6 * t;
+        if (t < 1 / 2) return q;
+        if (t < 2 / 3) return p + (q - p) * (2 / 3 - t) * 6;
+        return p;
+      };
+
+      const q = l < 0.5 ? l * (1 + s) : l + s - l * s;
+      const p = 2 * l - q;
+      r = hue2rgb(p, q, h + 1 / 3);
+      g = hue2rgb(p, q, h);
+      b = hue2rgb(p, q, h - 1 / 3);
+    }
+
+    return [r * 255, g * 255, b * 255];
+  }
+
+  function parseRGBA(color) {
+    const rgbaRegex = /rgba?\((\d+),\s*(\d+),\s*(\d+)/;
+    const match = color.match(rgbaRegex);
+    if (match) {
+      return [
+        parseInt(match[1], 10),
+        parseInt(match[2], 10),
+        parseInt(match[3], 10),
+      ];
+    }
+    return [255, 255, 255];
+  }
+
+  function map(value, start1, stop1, start2, stop2) {
+    return ((value - start1) / (stop1 - start1)) * (stop2 - start2) + start2;
+  }
+
+  /**
+   * Set the acceleration state of the starfield.
+   * @param {boolean} state The acceleration state.
+   */
+  function setAccelerate(state) {
+    accelerate = state;
+  }
+
+  /**
+   * Set the x-coordinate of the origin of the starfield.
+   * @param {number} x The x-coordinate of the origin.
+   */
+  function setOriginX(x) {
+    originX = x;
+    stars.forEach((star) => {
+      star.angle = Math.atan2(star.pos.y - originY, star.pos.x - originX);
+    });
+  }
+
+  /**
+   * Set the y-coordinate of the origin of the starfield.
+   * @param {number} y The y-coordinate of the origin.
+   */
+  function setOriginY(y) {
+    originY = y;
+    stars.forEach((star) => {
+      star.angle = Math.atan2(star.pos.y - originY, star.pos.x - originX);
+    });
+  }
+
+  /**
+   * Set the origin of the starfield to a specific point.
+   * @param {number} x The x-coordinate of the origin.
+   * @param {number} y The y-coordinate of the origin.
+   */
+  function setOrigin(x, y) {
+    originX = x;
+    originY = y;
+    stars.forEach((star) => {
+      star.angle = Math.atan2(star.pos.y - originY, star.pos.x - originX);
+    });
+  }
+
+  /**
+   * Resize the starfield to a new width and height.
+   * @param {number} newWidth The new width of the starfield.
+   * @param {number} newHeight The new height of the starfield.
+   */
+  function resize(newWidth, newHeight) {
+    width = newWidth;
+    height = newHeight;
+    canvas.width = width;
+    canvas.height = height;
+
+    if (config.originY !== null) {
+      originY = config.originY;
+    } else {
+      originY = height / 2;
+    }
+
+    stars.forEach((star) => star.reset());
+  }
+
+  function cleanup() {
+    if (origin) {
+      origin.removeEventListener("mouseenter", mouseEnterHandler);
+      origin.removeEventListener("mouseleave", mouseLeaveHandler);
+    }
+    window.removeEventListener("resize", resizeHandler);
+    document.removeEventListener("visibilitychange", visibilityHandler);
+
+    if (canvas && canvas.parentNode) {
+      canvas.parentNode.removeChild(canvas);
+    }
+
+    stars = [];
+    accelerate = false;
+    accelerationFactor = 0;
+    originX = 0;
+    originY = 0;
+    prevOriginX = 0;
+    prevOriginY = 0;
+    lastTimestamp = 0;
+  }
+
+  Starfield.setup = setup;
+  Starfield.setAccelerate = setAccelerate;
+  Starfield.setOrigin = setOrigin;
+  Starfield.setOriginX = setOriginX;
+  Starfield.setOriginY = setOriginY;
+  Starfield.resize = resize;
+  Starfield.config = config;
+  Starfield.cleanup = cleanup;
+
+  return Starfield;
+});

overrides/stylesheets/extra.css

@@ -552,3 +552,18 @@ a:hover .text-button span {
   width: 100%;
   height: 100%;
 }
+
+/* starfield */
+.starfield {
+  position: absolute;
+  width: 100%;
+  height: 100%;
+  z-index: 0;
+}
+
+.starfield-origin {
+  position: absolute;
+  top: 50%;
+  left: 50%;
+  transform: translate(-50%, -50%);
+}

zh-hant/docs/index.html

@@ -1,7 +1,10 @@
 <!-- Section: hero -->
 <section data-md-color-scheme="slate" data-md-color-primary="grey" class="home-div" style="height: min(100vh, 120vw); position: relative; margin-top:-2.4rem; padding: 0; overflow: hidden;">
     <!-- hero image -->
-    <img src="../assets/hero/universe_bg.png" class="hero-bg" alt="">
+    <!-- <img alt="" class="hero-bg" src="assets/hero/universe_bg.png" /> -->
+    <div class="starfield">
+        <div class="starfield-origin"></div>
+    </div>
     <div class="hero-div">
         <img src="../assets/hero/ground.png" alt="" style="position: absolute; width: auto; height: 26.445%; left: 28.211%; top: 54.145%;">
         <img src="../assets/hero/links.png" alt="" style="position: absolute; width: auto; height: 78.751%; left: 10.545%; top: 7.326%;">