Backlog - Webcam Reactive Experiment

Codice

body {
  margin: 0;
  font-family: "Trebuchet MS", "Segoe UI", sans-serif;
  background: #070e19;
  color: #eef4ff;
}
.topbar {
  padding: 0.75rem 1rem;
  display: flex;
  justify-content: space-between;
  align-items: center;
}
.topbar a {
  color: #8ee7ff;
  text-decoration: none;
}
button {
  border: 1px solid rgba(255, 255, 255, 0.25);
  background: rgba(255, 255, 255, 0.08);
  color: #eef4ff;
  border-radius: 999px;
  padding: 0.35rem 0.7rem;
}
main {
  width: min(980px, 92%);
  margin: 0 auto;
}
.kicker {
  color: #8ee7ff;
  text-transform: uppercase;
  letter-spacing: 0.1em;
}
.stage {
  margin-top: 1rem;
  position: relative;
  border: 1px solid #2b405f;
  border-radius: 14px;
  overflow: hidden;
  min-height: 300px;
}
video,
canvas {
  width: 100%;
  display: block;
}
video {
  filter: grayscale(1) contrast(1.2);
}
canvas {
  position: absolute;
  inset: 0;
  pointer-events: none;
}

if (!window.MotionPreference) {
  const __mql = window.matchMedia("(prefers-reduced-motion: reduce)");
  const __listeners = new Set();

  const MotionPreference = {
    prefersReducedMotion() {
      return __mql.matches;
    },
    setOverride(value) {
      const reduced = Boolean(value);
      document.documentElement.classList.toggle("reduced-motion", reduced);
      window.dispatchEvent(new CustomEvent("motion-preference", { detail: { reduced } }));
      for (const listener of __listeners) {
        try {
          listener({ reduced, override: reduced, systemReduced: __mql.matches });
        } catch {}
      }
    },
    onChange(listener) {
      __listeners.add(listener);
      try {
        listener({
          reduced: __mql.matches,
          override: null,
          systemReduced: __mql.matches,
        });
      } catch {}
      return () => __listeners.delete(listener);
    },
    getState() {
      return { reduced: __mql.matches, override: null, systemReduced: __mql.matches };
    },
  };

  window.MotionPreference = MotionPreference;
}

const startBtn = document.getElementById("startBtn");
const statusEl = document.getElementById("status");
const video = document.getElementById("video");
const canvas = document.getElementById("canvas");
const ctx = canvas.getContext("2d");
let stream;
let raf = 0;

function resize() {
  canvas.width = video.videoWidth || 640;
  canvas.height = video.videoHeight || 360;
}

function loop() {
  if (!video.videoWidth) {
    raf = requestAnimationFrame(loop);
    return;
  }
  resize();
  ctx.clearRect(0, 0, canvas.width, canvas.height);
  ctx.drawImage(video, 0, 0, canvas.width, canvas.height);
  const data = ctx.getImageData(0, 0, canvas.width, canvas.height).data;
  let sum = 0;
  for (let i = 0; i < data.length; i += 40) {
    sum += data[i] + data[i + 1] + data[i + 2];
  }
  const brightness = sum / ((data.length / 40) * 3 * 255);
  const radius = 40 + brightness * 220;

  ctx.globalCompositeOperation = "screen";
  const g = ctx.createRadialGradient(
    canvas.width / 2,
    canvas.height / 2,
    0,
    canvas.width / 2,
    canvas.height / 2,
    radius
  );
  g.addColorStop(0, "rgba(130,220,255,0.8)");
  g.addColorStop(1, "rgba(0,0,0,0)");
  ctx.fillStyle = g;
  ctx.beginPath();
  ctx.arc(canvas.width / 2, canvas.height / 2, radius, 0, Math.PI * 2);
  ctx.fill();
  ctx.globalCompositeOperation = "source-over";

  raf = requestAnimationFrame(loop);
}

startBtn.addEventListener("click", async () => {
  try {
    stream = await navigator.mediaDevices.getUserMedia({ video: true });
    video.srcObject = stream;
    statusEl.textContent = "Webcam reactive glow active.";
    cancelAnimationFrame(raf);
    raf = requestAnimationFrame(loop);
  } catch (error) {
    statusEl.textContent = "Webcam unavailable or permission denied.";
  }
});

window.addEventListener("beforeunload", () => {
  cancelAnimationFrame(raf);
  if (stream) stream.getTracks().forEach((t) => t.stop());
});

<!doctype html>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>Webcam Reactive Experiment</title>
    <link rel="stylesheet" href="style.css" />
  </head>
  <body>
    <header class="topbar">
      <a href="../">Back to demos</a>
      <button id="startBtn">Enable Webcam</button>
    </header>

    <main>
      <p class="kicker">Backlog 27</p>
      <h1>Webcam Reactive Experiment</h1>
      <p id="status">Waiting for permission...</p>
      <div class="stage">
        <video id="video" autoplay playsinline muted></video>
        <canvas id="canvas"></canvas>
      </div>
    </main>

    <script src="script.js"></script>
  </body>
</html>

Backlog - Webcam Reactive Experiment

Webcam brightness reactive overlay experiment with live camera input.

Source

Repository: libs-gen
Original demo id: 27-webcam-reactive-lab

Notes

Webcam brightness reactive overlay experiment with live camera input.