<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Phasor and Sine Wave Relationship</title>
  <style>
    * { box-sizing: border-box; margin: 0; padding: 0; }
    body {
      font-family: system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
      color: #0f172a;
      background: #ffffff;
      display: flex;
      flex-direction: column;
      align-items: center;
      justify-content: flex-start;
      width: 100%;
      min-height: 100%;
      padding: 6px 8px;
    }
    .diagram-wrap {
      width: 100%;
      max-width: 660px;
      display: flex;
      flex-direction: column;
      align-items: center;
    }
    svg {
      width: 100%;
      height: auto;
      max-width: 100%;
      display: block;
    }
    .controls {
      display: flex;
      flex-wrap: wrap;
      align-items: center;
      justify-content: center;
      gap: 10px 14px;
      margin-top: 4px;
      padding: 4px 0;
      width: 100%;
    }
    .btn {
      background: #f8fafc;
      border: 1px solid #94a3b8;
      border-radius: 6px;
      padding: 4px 12px;
      font-size: 13px;
      font-weight: 600;
      color: #0f172a;
      cursor: pointer;
      display: inline-flex;
      align-items: center;
      gap: 4px;
      transition: background-color 0.15s ease;
    }
    .btn:hover {
      background: #e2e8f0;
    }
    .slider-group {
      display: flex;
      align-items: center;
      gap: 8px;
    }
    .slider-label {
      font-size: 13px;
      font-weight: 600;
      color: #1e293b;
      white-space: nowrap;
    }
    input[type="range"] {
      cursor: pointer;
      accent-color: #0284c7;
      width: 130px;
      height: 6px;
    }
    @media (max-width: 480px) {
      .slider-label { font-size: 12px; }
      input[type="range"] { width: 110px; }
    }
  </style>
</head>
<body>
  <div class="diagram-wrap">
    <svg viewBox="0 0 650 245" aria-label="Phasor and Sine Wave Relationship">
      <defs>
        
        <marker id="arrow-axis" viewBox="0 0 10 10" refX="6" refY="5" markerWidth="6" markerHeight="6" orient="auto-start-reverse">
          <path d="M 0 1.5 L 8 5 L 0 8.5 z" fill="#475569" />
        </marker>
        <marker id="arrow-blue" viewBox="0 0 10 10" refX="6" refY="5" markerWidth="6" markerHeight="6" orient="auto-start-reverse">
          <path d="M 0 1.5 L 8 5 L 0 8.5 z" fill="#0284c7" />
        </marker>
        <marker id="arrow-omega" viewBox="0 0 10 10" refX="6" refY="5" markerWidth="6" markerHeight="6" orient="auto-start-reverse">
          <path d="M 0 1.5 L 8 5 L 0 8.5 z" fill="#0369a1" />
        </marker>
      </defs>

      
      <g id="phasor-domain">
        
        <circle cx="100" cy="125" r="72" fill="none" stroke="#cbd5e1" stroke-width="1.5" stroke-dasharray="4,4" />

        
        <line x1="16" y1="125" x2="190" y2="125" stroke="#64748b" stroke-width="1.2" marker-end="url(#arrow-axis)" />
        <line x1="100" y1="216" x2="100" y2="28" stroke="#64748b" stroke-width="1.2" marker-end="url(#arrow-axis)" />

        
        <line x1="100" y1="53" x2="30" y2="53" stroke="#94a3b8" stroke-width="1" stroke-dasharray="3,3" />
        <text x="26" y="57" text-anchor="end" font-size="11" font-weight="700" fill="#334155">+Vp</text>

        <line x1="100" y1="197" x2="30" y2="197" stroke="#94a3b8" stroke-width="1" stroke-dasharray="3,3" />
        <text x="26" y="201" text-anchor="end" font-size="11" font-weight="700" fill="#334155">-Vp</text>

        
        <path d="M 158 92 A 64 64 0 0 0 138 68" fill="none" stroke="#0369a1" stroke-width="1.5" marker-end="url(#arrow-omega)" />
        <text x="162" y="82" font-size="13" font-style="italic" font-weight="700" fill="#0369a1">ω</text>

        
        <path id="angle-arc" fill="none" stroke="#ea580c" stroke-width="1.8" />
        <text id="angle-text" x="126" y="117" font-size="11" font-weight="700" fill="#ea580c">θ</text>

        
        <line id="proj-v-axis" x1="100" y1="125" x2="100" y2="125" stroke="#ea580c" stroke-width="3" stroke-linecap="round" />
        <circle id="proj-v-dot" cx="100" cy="125" r="3.5" fill="#ea580c" />

        
        <line id="phasor-vector" x1="100" y1="125" x2="172" y2="125" stroke="#0284c7" stroke-width="2.5" marker-end="url(#arrow-blue)" />

        
        <text id="phasor-vp-label" x="135" y="112" font-size="11" font-weight="700" fill="#0284c7">Peak Vp</text>
      </g>

      
      <line id="connector-line" x1="172" y1="125" x2="240" y2="125" stroke="#ea580c" stroke-width="1.2" stroke-dasharray="3,3" />

      
      <g id="time-domain">
        
        <line x1="240" y1="53" x2="590" y2="53" stroke="#cbd5e1" stroke-width="1" stroke-dasharray="3,3" />
        <line x1="240" y1="197" x2="590" y2="197" stroke="#cbd5e1" stroke-width="1" stroke-dasharray="3,3" />

        
        <line x1="230" y1="125" x2="605" y2="125" stroke="#64748b" stroke-width="1.2" marker-end="url(#arrow-axis)" />
        <line x1="240" y1="216" x2="240" y2="28" stroke="#64748b" stroke-width="1.2" marker-end="url(#arrow-axis)" />

        
        <text x="642" y="129" text-anchor="end" font-size="11" font-weight="700" fill="#334155">Time (t)</text>
        <text x="240" y="18" text-anchor="middle" font-size="11" font-weight="700" fill="#334155">Voltage v(t)</text>
        <text x="234" y="57" text-anchor="end" font-size="11" font-weight="700" fill="#334155">+Vp</text>
        <text x="234" y="201" text-anchor="end" font-size="11" font-weight="700" fill="#334155">-Vp</text>

        
        <path id="guide-wave" fill="none" stroke="#cbd5e1" stroke-width="1.8" />

        
        <path id="active-wave" fill="none" stroke="#0284c7" stroke-width="2.5" />

        
        <circle id="wave-dot" cx="240" cy="125" r="5" fill="#ea580c" stroke="#ffffff" stroke-width="1.5" />

        
        <text id="instant-label" x="250" y="115" font-size="11" font-weight="700" fill="#ea580c">v(t) = Vp·sin(θ)</text>
      </g>
    </svg>

    
    <div class="controls">
      <button class="btn" id="playBtn" aria-label="Play or Pause">⏸ Pause</button>
      <div class="slider-group">
        <span class="slider-label">Angle θ = ωt: <strong id="degVal" style="color:#0284c7;">0°</strong></span>
        <input type="range" id="angleSlider" min="0" max="6.28318" step="0.02" value="0" aria-label="Angle in radians">
      </div>
    </div>
  </div>

  <script>
    const R = 72;
    const cx = 100;
    const cy = 125;
    const waveStart = 240;
    const waveLength = 330; // represents 2π period
    const totalWaveAngle = 2 * Math.PI;

    let angle = 0;
    let isPlaying = true;

    const phasorVec = document.getElementById('phasor-vector');
    const phasorVpLabel = document.getElementById('phasor-vp-label');
    const angleArc = document.getElementById('angle-arc');
    const angleText = document.getElementById('angle-text');
    const projAxis = document.getElementById('proj-v-axis');
    const projDot = document.getElementById('proj-v-dot');
    const connector = document.getElementById('connector-line');
    const guideWave = document.getElementById('guide-wave');
    const activeWave = document.getElementById('active-wave');
    const waveDot = document.getElementById('wave-dot');
    const instantLabel = document.getElementById('instant-label');
    const playBtn = document.getElementById('playBtn');
    const slider = document.getElementById('angleSlider');
    const degVal = document.getElementById('degVal');

    // Build static guide wave
    let guidePath = `M ${waveStart} ${cy}`;
    for (let x = 0; x <= waveLength; x += 3) {
      const a = (x / waveLength) * totalWaveAngle;
      const y = cy - R * Math.sin(a);
      guidePath += ` L ${(waveStart + x).toFixed(1)} ${y.toFixed(1)}`;
    }
    guideWave.setAttribute('d', guidePath);

    function updateDiagram(th) {
      const px = cx + R * Math.cos(th);
      const py = cy - R * Math.sin(th);

      // 1. Update Phasor Vector
      phasorVec.setAttribute('x2', px.toFixed(1));
      phasorVec.setAttribute('y2', py.toFixed(1));

      // Phasor Peak Vp text position offset from midpoint
      const midDist = R * 0.52;
      const midX = cx + midDist * Math.cos(th) - 14 * Math.sin(th);
      const midY = cy - midDist * Math.sin(th) - 14 * Math.cos(th);
      phasorVpLabel.setAttribute('x', midX.toFixed(1));
      phasorVpLabel.setAttribute('y', midY.toFixed(1));

      // 2. Dynamic Angle Arc (radius 24) sweeps strictly from 0 to current angle
      const arcR = 24;
      if (th > 0.04) {
        const arcEndX = cx + arcR * Math.cos(th);
        const arcEndY = cy - arcR * Math.sin(th);
        const largeArc = th > Math.PI ? 1 : 0;
        angleArc.setAttribute('d', `M ${cx + arcR} ${cy} A ${arcR} ${arcR} 0 ${largeArc} 0 ${arcEndX.toFixed(1)} ${arcEndY.toFixed(1)}`);
        angleArc.style.display = 'inline';

        const textDist = 34;
        const halfAngle = th * 0.5;
        angleText.setAttribute('x', (cx + textDist * Math.cos(halfAngle)).toFixed(1));
        angleText.setAttribute('y', (cy - textDist * Math.sin(halfAngle) + 4).toFixed(1));
        angleText.style.display = 'inline';
      } else {
        angleArc.setAttribute('d', '');
        angleText.style.display = 'none';
      }

      // 3. Vertical Projection on Phasor Axis
      projAxis.setAttribute('y2', py.toFixed(1));
      projDot.setAttribute('cy', py.toFixed(1));

      // 4. Wave Position & Traced Path
      const activeX = waveStart + (th / totalWaveAngle) * waveLength;
      
      let wavePath = `M ${waveStart} ${cy}`;
      const currentSpan = (th / totalWaveAngle) * waveLength;
      for (let x = 0; x <= currentSpan; x += 3) {
        const a = (x / waveLength) * totalWaveAngle;
        const y = cy - R * Math.sin(a);
        wavePath += ` L ${(waveStart + x).toFixed(1)} ${y.toFixed(1)}`;
      }
      wavePath += ` L ${activeX.toFixed(1)} ${py.toFixed(1)}`;
      activeWave.setAttribute('d', wavePath);

      // Wave Tracker Dot
      waveDot.setAttribute('cx', activeX.toFixed(1));
      waveDot.setAttribute('cy', py.toFixed(1));

      // Connector line across domains
      connector.setAttribute('x1', px.toFixed(1));
      connector.setAttribute('y1', py.toFixed(1));
      connector.setAttribute('x2', activeX.toFixed(1));
      connector.setAttribute('y2', py.toFixed(1));

      // Instantaneous Value label positioning
      const labelX = Math.min(Math.max(activeX - 35, waveStart + 5), 485);
      const labelY = py < cy ? Math.max(py - 9, 38) : Math.min(py + 17, 222);
      instantLabel.setAttribute('x', labelX.toFixed(1));
      instantLabel.setAttribute('y', labelY.toFixed(1));

      // Degree value display & slider sync
      const degrees = Math.round((th * 180) / Math.PI) % 360;
      degVal.textContent = degrees + '°';
      slider.value = th;
    }

    let lastTime = performance.now();
    function animate(now) {
      if (isPlaying) {
        const dt = (now - lastTime) / 1000;
        angle = (angle + dt * 1.1) % (2 * Math.PI);
        updateDiagram(angle);
      }
      lastTime = now;
      requestAnimationFrame(animate);
    }
    requestAnimationFrame(animate);

    // Interaction controls
    playBtn.addEventListener('click', () => {
      isPlaying = !isPlaying;
      playBtn.textContent = isPlaying ? '⏸ Pause' : '▶ Play';
    });

    slider.addEventListener('input', (e) => {
      isPlaying = false;
      playBtn.textContent = '▶ Play';
      angle = parseFloat(e.target.value);
      updateDiagram(angle);
    });

    // Initial render
    updateDiagram(0);
  </script>
</body>
</html>

Sinusoidal Alternating Current and Voltage Waveforms

<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Interactive Oscilloscope - AC Waveform</title>
  <style>
    * {
      box-sizing: border-box;
      margin: 0;
      padding: 0;
    }
    body {
      width: 100%;
      min-height: 100vh;
      background: #f8fafc;
      font-family: system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
      color: #1e2945;
      display: flex;
      flex-direction: column;
      align-items: center;
      justify-content: center;
      user-select: none;
      padding: 12px 8px;
    }
    .main-wrapper {
      width: 100%;
      max-width: 580px;
      display: flex;
      flex-direction: column;
      gap: 10px;
    }
    .scope-container {
      position: relative;
      width: 100%;
      aspect-ratio: 16 / 10;
      min-height: 220px;
      max-height: 380px;
      background: #0f172a;
      border-radius: 8px;
      overflow: hidden;
      box-shadow: inset 0 0 24px rgba(0, 0, 0, 0.7);
      cursor: crosshair;
      touch-action: none;
    }
    canvas {
      width: 100%;
      height: 100%;
      display: block;
    }
    .controls {
      display: flex;
      align-items: center;
      justify-content: space-between;
      width: 100%;
      gap: 8px;
      flex-wrap: wrap;
    }
    .btn {
      background: #ffffff;
      color: #1e2945;
      border: 1px solid #cbd5e1;
      border-radius: 6px;
      padding: 7px 14px;
      font-size: 13px;
      font-weight: 600;
      cursor: pointer;
      display: inline-flex;
      align-items: center;
      gap: 6px;
      transition: background-color 0.15s, border-color 0.15s;
    }
    .btn:hover {
      background: #f1f5f9;
      border-color: #94a3b8;
    }
    .btn:active {
      background: #e2e8f0;
    }
    .status-pill {
      font-size: 12px;
      font-weight: 600;
      color: #0284c7;
      background: #e0f2fe;
      padding: 6px 12px;
      border-radius: 20px;
      border: 1px solid #bae6fd;
      white-space: nowrap;
      text-align: right;
    }
    .tooltip {
      position: absolute;
      display: none;
      background: rgba(15, 23, 42, 0.95);
      border: 1px solid #0284c7;
      color: #f8fafc;
      font-size: 11px;
      font-family: ui-monospace, SFMono-Regular, Menlo, Monaco, Consolas, monospace;
      padding: 4px 8px;
      border-radius: 4px;
      pointer-events: none;
      transform: translate(-50%, -130%);
      white-space: nowrap;
      box-shadow: 0 4px 12px rgba(0,0,0,0.4);
      z-index: 10;
    }
    @media (max-width: 380px) {
      .btn {
        padding: 5px 10px;
        font-size: 12px;
      }
      .status-pill {
        font-size: 11px;
        padding: 5px 8px;
      }
    }
  </style>
</head>
<body>

  <div class="main-wrapper">
    <div class="scope-container" id="scope">
      <canvas id="canvas"></canvas>
      <div class="tooltip" id="tooltip"></div>
    </div>

    <div class="controls">
      <button class="btn" id="playBtn" aria-label="Toggle animation">
        <span id="btnIcon">⏸</span> <span id="btnText">Freeze Wave</span>
      </button>
      <div class="status-pill" id="instantV">v(t) = +0.00 V</div>
    </div>
  </div>

  <script>
    const canvas = document.getElementById('canvas');
    const ctx = canvas.getContext('2d');
    const scope = document.getElementById('scope');
    const tooltip = document.getElementById('tooltip');
    const playBtn = document.getElementById('playBtn');
    const btnIcon = document.getElementById('btnIcon');
    const btnText = document.getElementById('btnText');
    const instantV = document.getElementById('instantV');

    let width = 0;
    let height = 0;
    let isPlaying = true;
    let phase = 0;
    let mouseX = null;
    let mouseY = null;
    let isHovering = false;

    const Vp_val = 3.0; // Peak 3.0V for scale

    function resize() {
      const dpr = window.devicePixelRatio || 1;
      const rect = scope.getBoundingClientRect();
      width = rect.width;
      height = rect.height;
      canvas.width = Math.round(width * dpr);
      canvas.height = Math.round(height * dpr);
      ctx.resetTransform();
      ctx.scale(dpr, dpr);
    }

    window.addEventListener('resize', resize);
    resize();

    function drawGrid() {
      const cols = 10;
      const rows = 8;
      const dx = width / cols;
      const dy = height / rows;

      ctx.strokeStyle = '#1e293b';
      ctx.lineWidth = 1;

      // Minor grid lines
      for (let i = 0; i <= cols; i++) {
        const x = Math.round(i * dx) + 0.5;
        ctx.beginPath();
        ctx.moveTo(x, 0);
        ctx.lineTo(x, height);
        ctx.stroke();
      }
      for (let j = 0; j <= rows; j++) {
        const y = Math.round(j * dy) + 0.5;
        ctx.beginPath();
        ctx.moveTo(0, y);
        ctx.lineTo(width, y);
        ctx.stroke();
      }

      // Center crosshairs (t-axis and 0V line)
      ctx.strokeStyle = '#334155';
      ctx.lineWidth = 1.5;

      const midY = Math.round(height / 2) + 0.5;
      const midX = Math.round(width / 2) + 0.5;

      ctx.beginPath();
      ctx.moveTo(0, midY);
      ctx.lineTo(width, midY);
      ctx.stroke();

      // Tick marks on axes
      ctx.strokeStyle = '#475569';
      ctx.lineWidth = 1;
      for (let i = 0; i <= cols * 5; i++) {
        const x = i * (dx / 5);
        ctx.beginPath();
        ctx.moveTo(x, midY - 2.5);
        ctx.lineTo(x, midY + 2.5);
        ctx.stroke();
      }
      for (let j = 0; j <= rows * 5; j++) {
        const y = j * (dy / 5);
        ctx.beginPath();
        ctx.moveTo(midX - 2.5, y);
        ctx.lineTo(midX + 2.5, y);
        ctx.stroke();
      }
    }

    function getWaveParams() {
      // Dynamic scaling for responsiveness
      const curPeriod = Math.min(width * 0.42, 210);
      const curAmp = Math.min(height * 0.28, 70);
      const midY = height / 2;
      return { curPeriod, curAmp, midY };
    }

    function drawWave() {
      const { curPeriod, curAmp, midY } = getWaveParams();

      ctx.save();
      ctx.shadowColor = '#0284c7';
      ctx.shadowBlur = 8;
      ctx.strokeStyle = '#38bdf8';
      ctx.lineWidth = 2.5;

      ctx.beginPath();
      for (let x = 0; x <= width; x++) {
        const angle = ((x / curPeriod) * Math.PI * 2) - phase;
        const y = midY - Math.sin(angle) * curAmp;
        if (x === 0) ctx.moveTo(x, y);
        else ctx.lineTo(x, y);
      }
      ctx.stroke();
      ctx.restore();
    }

    function drawBracket(x1, y1, x2, y2, tickDir, text, subText, textSide = 'right', fontScale = 1) {
      ctx.save();
      ctx.strokeStyle = '#94a3b8';
      ctx.fillStyle = '#f8fafc';
      ctx.lineWidth = 1.25;

      const mainSize = Math.max(9.5, Math.round(11 * fontScale));
      const subSize = Math.max(8, Math.round(9.5 * fontScale));
      const tick = 4.5 * tickDir;

      const isVertical = Math.abs(x1 - x2) < 2;

      ctx.beginPath();
      if (isVertical) {
        // Vertical bracket
        ctx.moveTo(x1, y1);
        ctx.lineTo(x2, y2);
        ctx.moveTo(x1 - tick, y1);
        ctx.lineTo(x1 + tick, y1);
        ctx.moveTo(x2 - tick, y2);
        ctx.lineTo(x2 + tick, y2);
        ctx.stroke();

        const my = (y1 + y2) / 2;
        const offset = 6 * fontScale;
        const tx = textSide === 'right' ? x1 + offset : x1 - offset;

        ctx.font = `600 ${mainSize}px system-ui, sans-serif`;
        ctx.textAlign = textSide === 'right' ? 'left' : 'right';
        ctx.textBaseline = 'middle';
        ctx.fillText(text, tx, my - (mainSize * 0.55));

        ctx.font = `400 ${subSize}px system-ui, sans-serif`;
        ctx.fillStyle = '#94a3b8';
        ctx.fillText(subText, tx, my + (subSize * 0.65));
      } else {
        // Horizontal bracket
        ctx.moveTo(x1, y1);
        ctx.lineTo(x2, y2);
        ctx.moveTo(x1, y1 - tick);
        ctx.lineTo(x1, y1 + tick);
        ctx.moveTo(x2, y2 - tick);
        ctx.lineTo(x2, y2 + tick);
        ctx.stroke();

        const mx = (x1 + x2) / 2;
        const ty = y1 - 6;

        ctx.font = `600 ${mainSize}px system-ui, sans-serif`;
        ctx.textAlign = 'center';
        ctx.textBaseline = 'bottom';
        ctx.fillText(text, mx, ty);

        ctx.font = `400 ${subSize}px system-ui, sans-serif`;
        ctx.fillStyle = '#94a3b8';
        ctx.fillText(subText, mx, ty + (subSize * 1.05));
      }
      ctx.restore();
    }

    function drawAnnotations() {
      const { curPeriod, curAmp, midY } = getWaveParams();
      const fontScale = Math.max(0.75, Math.min(1.0, width / 450));

      // 1. Period (T) bracket across 1 full cycle
      const tStartX = Math.max(16, width * 0.06);
      const tEndX = tStartX + curPeriod;
      const tY = Math.max(20, height * 0.15);

      drawBracket(tStartX, tY, tEndX, tY, 1, 'Period (T)', '1 Cycle', 'center', fontScale);

      // Dashed vertical guidelines for Period
      ctx.save();
      ctx.setLineDash([3, 3]);
      ctx.strokeStyle = '#334155';
      ctx.lineWidth = 1;
      ctx.beginPath();
      ctx.moveTo(tStartX, tY);
      ctx.lineTo(tStartX, midY + curAmp + 8);
      ctx.moveTo(tEndX, tY);
      ctx.lineTo(tEndX, midY + curAmp + 8);
      ctx.stroke();
      ctx.restore();

      // 2. Peak Voltage (Vp): Baseline to Crest
      const vpX = Math.min(width * 0.50, tEndX + 20);
      drawBracket(vpX, midY, vpX, midY - curAmp, 1, 'Peak (Vp)', '0V to Crest', 'right', fontScale);

      // 3. Peak-to-Peak (Vpp): Trough to Crest
      // Keep inside right edge with safety margin
      const vppX = width - Math.max(12, width * 0.04);
      drawBracket(vppX, midY + curAmp, vppX, midY - curAmp, 1, 'Peak-to-Peak (Vpp)', 'Trough to Crest', 'left', fontScale);
    }

    function drawCursor() {
      if (mouseX === null || !isHovering) return;

      const { curPeriod, curAmp, midY } = getWaveParams();
      const angle = ((mouseX / curPeriod) * Math.PI * 2) - phase;
      const waveY = midY - Math.sin(angle) * curAmp;
      const vInst = (Math.sin(angle) * Vp_val).toFixed(2);
      const sign = Number(vInst) >= 0 ? '+' : '';

      // Indicator circle on the wave
      ctx.save();
      ctx.fillStyle = '#38bdf8';
      ctx.shadowColor = '#38bdf8';
      ctx.shadowBlur = 10;
      ctx.beginPath();
      ctx.arc(mouseX, waveY, 4.5, 0, Math.PI * 2);
      ctx.fill();

      // Vertical tracker guideline
      ctx.setLineDash([2, 2]);
      ctx.strokeStyle = 'rgba(56, 189, 248, 0.45)';
      ctx.lineWidth = 1;
      ctx.beginPath();
      ctx.moveTo(mouseX, 0);
      ctx.lineTo(mouseX, height);
      ctx.stroke();
      ctx.restore();

      // Clamp tooltip position horizontally so it never overflows screen edge
      const clampedX = Math.max(55, Math.min(width - 55, mouseX));
      const clampedY = Math.max(35, waveY);

      tooltip.style.display = 'block';
      tooltip.style.left = `${clampedX}px`;
      tooltip.style.top = `${clampedY}px`;
      tooltip.innerHTML = `t: ${(mouseX / 50).toFixed(1)}ms &nbsp;|&nbsp; <b>v(t) = ${sign}${vInst}V</b>`;

      instantV.textContent = `v(t) = ${sign}${vInst} V`;
    }

    function render() {
      ctx.clearRect(0, 0, width, height);

      drawGrid();
      drawWave();
      drawAnnotations();
      drawCursor();

      if (isPlaying) {
        phase += 0.035;
      }
      requestAnimationFrame(render);
    }

    requestAnimationFrame(render);

    // Play / Freeze control
    playBtn.addEventListener('click', () => {
      isPlaying = !isPlaying;
      btnIcon.textContent = isPlaying ? '⏸' : '▶';
      btnText.textContent = isPlaying ? 'Freeze Wave' : 'Resume Wave';
    });

    // Unified pointer tracking (desktop hover & mobile touch)
    function handlePointer(e) {
      const rect = scope.getBoundingClientRect();
      mouseX = Math.max(0, Math.min(width, e.clientX - rect.left));
      mouseY = Math.max(0, Math.min(height, e.clientY - rect.top));
      isHovering = true;
    }

    scope.addEventListener('pointermove', handlePointer);
    scope.addEventListener('pointerenter', handlePointer);
    scope.addEventListener('pointerdown', handlePointer);

    scope.addEventListener('pointerleave', () => {
      isHovering = false;
      tooltip.style.display = 'none';
      instantV.textContent = 'Touch trace to probe v(t)';
    });
  </script>
</body>
</html>

ELEC-13.1

Aligned learning resources

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