Add dynamic WebGL background with audio reactivity

- WebGL shader background with flowing waves, radial pulse, and frequency ring arcs
- Reacts to captured audio data (frequency bands + bass) when visualizer is active
- Uses page accent color; adapts to dark/light theme via bg-primary blending
- Toggle button in header toolbar, state persisted in localStorage
- Cached uniform locations and color values to avoid per-frame getComputedStyle calls
- i18n support for EN/RU locales

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

media_server/static/css/styles.css

@@ -63,6 +63,27 @@
     box-shadow: 0 -2px 8px rgba(0, 0, 0, 0.08);
 }
 
+/* Dynamic Background Canvas */
+.bg-shader-canvas {
+    position: fixed;
+    top: 0;
+    left: 0;
+    width: 100vw;
+    height: 100vh;
+    z-index: -1;
+    pointer-events: none;
+    opacity: 0;
+    transition: opacity 0.6s ease;
+}
+
+.bg-shader-canvas.visible {
+    opacity: 1;
+}
+
+body.dynamic-bg-active {
+    background: transparent;
+}
+
 * {
     margin: 0;
     padding: 0;
@@ -218,6 +239,10 @@ h1 {
     background: var(--bg-tertiary);
 }
 
+.header-btn.active {
+    color: var(--accent);
+}
+
 .header-btn svg {
     width: 16px;
     height: 16px;
@@ -3165,7 +3190,6 @@ footer .separator {
     font-weight: 500;
     text-align: center;
     transition: transform 0.3s ease;
-    animation: bannerSlideIn 0.4s ease-out;
 }
 
 .connection-banner:not(.hidden) {

media_server/static/index.html

@@ -57,6 +57,9 @@
         </div>
     </div>
 
+    <!-- Dynamic Background -->
+    <canvas id="bg-shader-canvas" class="bg-shader-canvas"></canvas>
+
     <!-- Auth Modal -->
     <div id="auth-overlay" class="hidden">
         <div class="auth-modal">
@@ -86,6 +89,9 @@
                     </button>
                     <div class="accent-picker-dropdown" id="accentDropdown"></div>
                 </div>
+                <button class="header-btn" onclick="toggleDynamicBackground()" data-i18n-title="player.background" title="Dynamic background" aria-label="Dynamic background" id="bgToggle">
+                    <svg viewBox="0 0 24 24"><path fill="currentColor" d="M12 3v10.55A4 4 0 1 0 14 17V7h4V3h-6z"/></svg>
+                </button>
                 <button class="header-btn" onclick="toggleTheme()" data-i18n-title="player.theme" title="Toggle theme" aria-label="Toggle theme" id="theme-toggle">
                     <svg id="theme-icon-sun" viewBox="0 0 24 24" style="display: none;">
                         <path d="M12 7c-2.76 0-5 2.24-5 5s2.24 5 5 5 5-2.24 5-5-2.24-5-5-5zM2 13h2c.55 0 1-.45 1-1s-.45-1-1-1H2c-.55 0-1 .45-1 1s.45 1 1 1zm18 0h2c.55 0 1-.45 1-1s-.45-1-1-1h-2c-.55 0-1 .45-1 1s.45 1 1 1zM11 2v2c0 .55.45 1 1 1s1-.45 1-1V2c0-.55-.45-1-1-1s-1 .45-1 1zm0 18v2c0 .55.45 1 1 1s1-.45 1-1v-2c0-.55-.45-1-1-1s-1 .45-1 1zM5.99 4.58c-.39-.39-1.03-.39-1.41 0-.39.39-.39 1.03 0 1.41l1.06 1.06c.39.39 1.03.39 1.41 0s.39-1.03 0-1.41L5.99 4.58zm12.37 12.37c-.39-.39-1.03-.39-1.41 0-.39.39-.39 1.03 0 1.41l1.06 1.06c.39.39 1.03.39 1.41 0 .39-.39.39-1.03 0-1.41l-1.06-1.06zm1.06-10.96c.39-.39.39-1.03 0-1.41-.39-.39-1.03-.39-1.41 0l-1.06 1.06c-.39.39-.39 1.03 0 1.41s1.03.39 1.41 0l1.06-1.06zM7.05 18.36c.39-.39.39-1.03 0-1.41-.39-.39-1.03-.39-1.41 0l-1.06 1.06c-.39.39-.39 1.03 0 1.41s1.03.39 1.41 0l1.06-1.06z"/>
@@ -652,6 +658,7 @@
     <script src="/static/js/callbacks.js"></script>
     <script src="/static/js/browser.js"></script>
     <script src="/static/js/links.js"></script>
+    <script src="/static/js/background.js"></script>
     <script src="/static/js/main.js"></script>
 </body>
 </html>

media_server/static/js/background.js

@@ -0,0 +1,314 @@
+// ============================================================
+// Background: WebGL shader-based dynamic background
+// ============================================================
+
+let bgCanvas = null;
+let bgGL = null;
+let bgProgram = null;
+let bgUniforms = null;       // Cached uniform locations
+let bgAnimFrame = null;
+let bgEnabled = localStorage.getItem('dynamicBackground') === 'true';
+let bgStartTime = 0;
+let bgSmoothedBands = new Float32Array(16);
+let bgSmoothedBass = 0;
+let bgAccentRGB = [0.114, 0.725, 0.329]; // Cached accent color (default green)
+let bgBgColorRGB = [0.071, 0.071, 0.071]; // Cached page background (#121212)
+
+const BG_BAND_COUNT = 16;
+const BG_SMOOTHING = 0.12;
+
+// ---- Shaders ----
+
+const BG_VERT_SRC = `
+attribute vec2 a_position;
+void main() {
+    gl_Position = vec4(a_position, 0.0, 1.0);
+}
+`;
+
+const BG_FRAG_SRC = `
+precision mediump float;
+
+uniform vec2 u_resolution;
+uniform float u_time;
+uniform float u_bass;
+uniform float u_bands[16];
+uniform vec3 u_accent;
+uniform vec3 u_bgColor;
+
+// Smooth noise
+float hash(vec2 p) {
+    return fract(sin(dot(p, vec2(127.1, 311.7))) * 43758.5453);
+}
+
+float noise(vec2 p) {
+    vec2 i = floor(p);
+    vec2 f = fract(p);
+    f = f * f * (3.0 - 2.0 * f);
+    float a = hash(i);
+    float b = hash(i + vec2(1.0, 0.0));
+    float c = hash(i + vec2(0.0, 1.0));
+    float d = hash(i + vec2(1.0, 1.0));
+    return mix(mix(a, b, f.x), mix(c, d, f.x), f.y);
+}
+
+void main() {
+    vec2 uv = gl_FragCoord.xy / u_resolution;
+    float aspect = u_resolution.x / u_resolution.y;
+
+    // Center coordinates for radial effects
+    vec2 center = (uv - 0.5) * vec2(aspect, 1.0);
+    float dist = length(center);
+    float angle = atan(center.y, center.x);
+
+    // Slow base animation
+    float t = u_time * 0.15;
+
+    // === Layer 1: Flowing wave field ===
+    float waves = 0.0;
+    for (int i = 0; i < 5; i++) {
+        float fi = float(i);
+        float freq = 1.5 + fi * 0.8;
+        float speed = t * (0.6 + fi * 0.15);
+        // Sample a band for this wave layer
+        int bandIdx = i * 3;
+        float bandVal = 0.0;
+        // Manual indexing (GLSL ES doesn't allow variable array index in some drivers)
+        for (int j = 0; j < 16; j++) {
+            if (j == bandIdx) bandVal = u_bands[j];
+        }
+        float amp = 0.015 + bandVal * 0.06;
+        waves += amp * sin(uv.x * freq * 6.2832 + speed + sin(uv.y * 3.0 + t) * 2.0);
+        waves += amp * 0.5 * sin(uv.y * freq * 4.0 - speed * 0.7 + cos(uv.x * 2.5 + t) * 1.5);
+    }
+
+    // === Layer 2: Radial pulse (bass-driven) ===
+    float pulse = smoothstep(0.6 + u_bass * 0.3, 0.0, dist) * (0.08 + u_bass * 0.15);
+
+    // === Layer 3: Frequency ring arcs ===
+    float rings = 0.0;
+    for (int i = 0; i < 8; i++) {
+        float fi = float(i);
+        float bandVal = 0.0;
+        for (int j = 0; j < 16; j++) {
+            if (j == i * 2) bandVal = u_bands[j];
+        }
+        float radius = 0.15 + fi * 0.1;
+        float ringWidth = 0.008 + bandVal * 0.025;
+        float ring = smoothstep(ringWidth, 0.0, abs(dist - radius - bandVal * 0.05));
+        // Fade ring by angle sector for variety
+        float angleFade = 0.5 + 0.5 * sin(angle * (2.0 + fi) + t * (1.0 + fi * 0.3));
+        rings += ring * angleFade * (0.3 + bandVal * 0.7);
+    }
+
+    // === Layer 4: Subtle noise texture ===
+    float n = noise(uv * 4.0 + t * 0.5) * 0.03;
+
+    // Combine layers
+    float intensity = waves + pulse + rings * 0.5 + n;
+
+    // Color: accent color with varying brightness
+    vec3 col = u_accent * intensity;
+
+    // Subtle secondary hue shift for depth
+    vec3 shifted = u_accent.gbr;  // Rotated accent
+    col += shifted * rings * 0.15;
+
+    // Vignette
+    float vignette = 1.0 - smoothstep(0.3, 1.2, dist);
+    col *= vignette;
+
+    // Blend over page background
+    col = clamp(col, 0.0, 1.0);
+    float colBright = (col.r + col.g + col.b) / 3.0;
+    float bgLum = dot(u_bgColor, vec3(0.299, 0.587, 0.114));
+    // Dark bg: add accent light.  Light bg: tint white toward accent via multiply.
+    vec3 darkResult  = u_bgColor + col;
+    vec3 lightResult = u_bgColor * mix(vec3(1.0), u_accent, colBright * 2.0);
+    vec3 finalColor = clamp(mix(darkResult, lightResult, bgLum), 0.0, 1.0);
+
+    gl_FragColor = vec4(finalColor, 1.0);
+}
+`;
+
+// ---- WebGL setup ----
+
+function initBackgroundGL() {
+    bgCanvas = document.getElementById('bg-shader-canvas');
+    if (!bgCanvas) return false;
+
+    bgGL = bgCanvas.getContext('webgl', { alpha: false, antialias: false, depth: false, stencil: false });
+    if (!bgGL) {
+        console.warn('WebGL not available for background shader');
+        return false;
+    }
+
+    const gl = bgGL;
+
+    // Compile shaders
+    const vs = gl.createShader(gl.VERTEX_SHADER);
+    gl.shaderSource(vs, BG_VERT_SRC);
+    gl.compileShader(vs);
+    if (!gl.getShaderParameter(vs, gl.COMPILE_STATUS)) {
+        console.error('BG vertex shader:', gl.getShaderInfoLog(vs));
+        return false;
+    }
+
+    const fs = gl.createShader(gl.FRAGMENT_SHADER);
+    gl.shaderSource(fs, BG_FRAG_SRC);
+    gl.compileShader(fs);
+    if (!gl.getShaderParameter(fs, gl.COMPILE_STATUS)) {
+        console.error('BG fragment shader:', gl.getShaderInfoLog(fs));
+        return false;
+    }
+
+    bgProgram = gl.createProgram();
+    gl.attachShader(bgProgram, vs);
+    gl.attachShader(bgProgram, fs);
+    gl.linkProgram(bgProgram);
+    if (!gl.getProgramParameter(bgProgram, gl.LINK_STATUS)) {
+        console.error('BG program link:', gl.getProgramInfoLog(bgProgram));
+        return false;
+    }
+
+    // Fullscreen quad
+    const buf = gl.createBuffer();
+    gl.bindBuffer(gl.ARRAY_BUFFER, buf);
+    gl.bufferData(gl.ARRAY_BUFFER, new Float32Array([
+        -1, -1,  1, -1,  -1, 1,
+        -1,  1,  1, -1,   1, 1
+    ]), gl.STATIC_DRAW);
+
+    const aPos = gl.getAttribLocation(bgProgram, 'a_position');
+    gl.enableVertexAttribArray(aPos);
+    gl.vertexAttribPointer(aPos, 2, gl.FLOAT, false, 0, 0);
+
+    gl.useProgram(bgProgram);
+
+    // Cache uniform locations once (avoids per-frame lookups)
+    bgUniforms = {
+        resolution: gl.getUniformLocation(bgProgram, 'u_resolution'),
+        time:       gl.getUniformLocation(bgProgram, 'u_time'),
+        bass:       gl.getUniformLocation(bgProgram, 'u_bass'),
+        bands:      gl.getUniformLocation(bgProgram, 'u_bands'),
+        accent:     gl.getUniformLocation(bgProgram, 'u_accent'),
+        bgColor:    gl.getUniformLocation(bgProgram, 'u_bgColor'),
+    };
+
+    bgStartTime = performance.now() / 1000;
+    updateBackgroundColors();
+    resizeBackgroundCanvas();
+    window.addEventListener('resize', resizeBackgroundCanvas);
+
+    return true;
+}
+
+function resizeBackgroundCanvas() {
+    if (!bgCanvas) return;
+    const dpr = Math.min(window.devicePixelRatio || 1, 1.5); // Cap DPR for performance
+    const w = Math.floor(window.innerWidth * dpr);
+    const h = Math.floor(window.innerHeight * dpr);
+    if (bgCanvas.width !== w || bgCanvas.height !== h) {
+        bgCanvas.width = w;
+        bgCanvas.height = h;
+    }
+}
+
+// ---- Cached color/theme updates (called on accent or theme change, not per-frame) ----
+
+function updateBackgroundColors() {
+    const style = getComputedStyle(document.documentElement);
+    const accentHex = style.getPropertyValue('--accent').trim();
+    if (accentHex && accentHex.length >= 7) {
+        bgAccentRGB[0] = parseInt(accentHex.slice(1, 3), 16) / 255;
+        bgAccentRGB[1] = parseInt(accentHex.slice(3, 5), 16) / 255;
+        bgAccentRGB[2] = parseInt(accentHex.slice(5, 7), 16) / 255;
+    }
+    const bgHex = style.getPropertyValue('--bg-primary').trim();
+    if (bgHex && bgHex.length >= 7) {
+        bgBgColorRGB[0] = parseInt(bgHex.slice(1, 3), 16) / 255;
+        bgBgColorRGB[1] = parseInt(bgHex.slice(3, 5), 16) / 255;
+        bgBgColorRGB[2] = parseInt(bgHex.slice(5, 7), 16) / 255;
+    }
+}
+
+// ---- Render loop ----
+
+function renderBackgroundFrame() {
+    bgAnimFrame = requestAnimationFrame(renderBackgroundFrame);
+
+    const gl = bgGL;
+    if (!gl || !bgUniforms) return;
+
+    resizeBackgroundCanvas();
+    gl.viewport(0, 0, bgCanvas.width, bgCanvas.height);
+
+    const time = performance.now() / 1000 - bgStartTime;
+
+    // Smooth audio data from the global frequencyData (shared with visualizer)
+    if (typeof frequencyData !== 'undefined' && frequencyData && frequencyData.frequencies) {
+        const bins = frequencyData.frequencies;
+        const step = Math.max(1, Math.floor(bins.length / BG_BAND_COUNT));
+        for (let i = 0; i < BG_BAND_COUNT; i++) {
+            const idx = Math.min(i * step, bins.length - 1);
+            const target = bins[idx] || 0;
+            bgSmoothedBands[i] += (target - bgSmoothedBands[i]) * (1 - BG_SMOOTHING);
+        }
+        const targetBass = frequencyData.bass || 0;
+        bgSmoothedBass += (targetBass - bgSmoothedBass) * (1 - BG_SMOOTHING);
+    } else {
+        // Gentle decay when no audio
+        for (let i = 0; i < BG_BAND_COUNT; i++) {
+            bgSmoothedBands[i] *= 0.95;
+        }
+        bgSmoothedBass *= 0.95;
+    }
+
+    // Set uniforms (locations cached at init, colors cached on change)
+    gl.uniform2f(bgUniforms.resolution, bgCanvas.width, bgCanvas.height);
+    gl.uniform1f(bgUniforms.time, time);
+    gl.uniform1f(bgUniforms.bass, bgSmoothedBass);
+    gl.uniform1fv(bgUniforms.bands, bgSmoothedBands);
+    gl.uniform3f(bgUniforms.accent, bgAccentRGB[0], bgAccentRGB[1], bgAccentRGB[2]);
+    gl.uniform3f(bgUniforms.bgColor, bgBgColorRGB[0], bgBgColorRGB[1], bgBgColorRGB[2]);
+
+    gl.drawArrays(gl.TRIANGLES, 0, 6);
+}
+
+function startBackground() {
+    if (bgAnimFrame) return;
+    if (!bgGL && !initBackgroundGL()) return;
+    bgCanvas.classList.add('visible');
+    document.body.classList.add('dynamic-bg-active');
+    renderBackgroundFrame();
+}
+
+function stopBackground() {
+    if (bgAnimFrame) {
+        cancelAnimationFrame(bgAnimFrame);
+        bgAnimFrame = null;
+    }
+    if (bgCanvas) {
+        bgCanvas.classList.remove('visible');
+    }
+    document.body.classList.remove('dynamic-bg-active');
+}
+
+// ---- Public API ----
+
+function toggleDynamicBackground() {
+    bgEnabled = !bgEnabled;
+    localStorage.setItem('dynamicBackground', bgEnabled);
+    applyDynamicBackground();
+}
+
+function applyDynamicBackground() {
+    const btn = document.getElementById('bgToggle');
+    if (bgEnabled) {
+        startBackground();
+        if (btn) btn.classList.add('active');
+    } else {
+        stopBackground();
+        if (btn) btn.classList.remove('active');
+    }
+}

media_server/static/js/main.js

@@ -25,6 +25,9 @@ window.addEventListener('DOMContentLoaded', async () => {
         }
     });
 
+    // Initialize dynamic background
+    applyDynamicBackground();
+
     // Initialize locale (async - loads JSON file)
     await initLocale();
 

media_server/static/js/player.js

@@ -99,6 +99,8 @@ function setTheme(theme) {
     if (metaThemeColor) {
         metaThemeColor.setAttribute('content', theme === 'light' ? '#ffffff' : '#121212');
     }
+
+    if (typeof updateBackgroundColors === 'function') updateBackgroundColors();
 }
 
 function toggleTheme() {
@@ -147,6 +149,7 @@ function applyAccentColor(color, hover) {
     localStorage.setItem('accentColor', color);
     const dot = document.getElementById('accentDot');
     if (dot) dot.style.background = color;
+    if (typeof updateBackgroundColors === 'function') updateBackgroundColors();
 }
 
 function renderAccentSwatches() {

media_server/static/locales/en.json

@@ -24,6 +24,7 @@
   "player.unknown_source": "Unknown",
   "player.vinyl": "Vinyl mode",
   "player.visualizer": "Audio visualizer",
+  "player.background": "Dynamic background",
   "state.playing": "Playing",
   "state.paused": "Paused",
   "state.stopped": "Stopped",

media_server/static/locales/ru.json

@@ -24,6 +24,7 @@
   "player.unknown_source": "Неизвестно",
   "player.vinyl": "Режим винила",
   "player.visualizer": "Аудио визуализатор",
+  "player.background": "Динамический фон",
   "state.playing": "Воспроизведение",
   "state.paused": "Пауза",
   "state.stopped": "Остановлено",