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Browse files- index.html +395 -18
index.html
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</html>
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<!DOCTYPE html>
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<html lang="en">
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<head>
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<meta charset="UTF-8" />
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<meta name="viewport" content="width=device-width, initial-scale=1.0" />
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<meta name="description" content="Interactive app to teach kids about rotation symmetry in shapes" />
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<meta name="keywords" content="rotation symmetry, kids education, shapes, interactive learning" />
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<title>Rotation Symmetry Explorer</title>
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<style>
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:root {
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--bg: #ffffff;
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--text: #111827; /* gray-900 */
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--muted: #6b7280; /* gray-500 */
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--grid: #e5e7eb; /* gray-200 */
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--accent: #2563eb; /* blue-600 */
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--good: #16a34a; /* green-600 */
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--danger: #ef4444; /* red-500 */
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--card: #f9fafb; /* gray-50 */
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--shadow: 0 6px 20px rgba(0,0,0,0.08);
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--radius: 16px;
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}
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* { box-sizing: border-box; }
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body { margin: 0; font-family: ui-sans-serif, system-ui, -apple-system, Segoe UI, Roboto, "Helvetica Neue", Arial, "Noto Sans", "Apple Color Emoji", "Segoe UI Emoji"; color: var(--text); background: var(--bg); }
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header { padding: 24px 16px; text-align: center; }
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header h1 { margin: 0 0 4px; font-size: 2rem; }
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header p { margin: 0; color: #374151; }
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main { padding: 16px; max-width: 1200px; margin: 0 auto; }
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.intro { background: var(--card); padding: 16px; border-radius: var(--radius); box-shadow: var(--shadow); margin-bottom: 20px; }
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.intro h2 { margin-top: 0; font-size: 1.25rem; }
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.explorer { display: grid; grid-template-columns: 1.5fr 1fr; gap: 16px; align-items: start; }
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@media (max-width: 900px) { .explorer { grid-template-columns: 1fr; } }
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.shape-container { background: var(--card); padding: 12px; border-radius: var(--radius); box-shadow: var(--shadow); }
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.shape-stage { position: relative; border-radius: 12px; overflow: hidden; background: #fff; height: 420px; border: 1px solid #e5e7eb; }
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canvas { width: 100%; height: 100%; display: block; cursor: default; }
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canvas.drawing { cursor: crosshair; }
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.controls { background: #fff; padding: 16px; border-radius: var(--radius); box-shadow: var(--shadow); display: grid; gap: 12px; }
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.controls label { font-size: 0.9rem; color: #374151; display: block; margin-bottom: 4px; }
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.row { display: flex; align-items: center; gap: 10px; flex-wrap: wrap; }
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.row input[type="range"] { flex: 1; }
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.btn { appearance: none; border: 1px solid #e5e7eb; background: #fff; padding: 8px 12px; border-radius: 12px; box-shadow: var(--shadow); font-weight: 600; cursor: pointer; }
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.btn:active { transform: translateY(1px); }
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.btn.primary { background: var(--accent); color: #fff; border-color: var(--accent); }
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.btn.ghost { background: #f3f4f6; }
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.toggle { display: inline-flex; align-items: center; gap: 8px; }
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select, input[type="range"], input[type="checkbox"] { accent-color: var(--accent); }
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select { width: 100%; padding: 8px 10px; border-radius: 12px; border: 1px solid #e5e7eb; background: #fff; }
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.info { background: var(--card); padding: 12px 16px; border-radius: var(--radius); box-shadow: var(--shadow); }
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.info h3 { margin: 0 0 6px; }
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.examples { margin-top: 24px; }
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.shapes-grid { display: grid; grid-template-columns: repeat(6, 1fr); gap: 12px; }
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@media (max-width: 900px) { .shapes-grid { grid-template-columns: repeat(3, 1fr); } }
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.shape-item { background: #fff; padding: 10px; text-align: center; border: 1px solid #e5e7eb; border-radius: 12px; cursor: pointer; box-shadow: var(--shadow); }
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.shape-item p { margin: 8px 0 0; font-size: 0.9rem; }
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.example-shape { width: 56px; height: 56px; margin: 0 auto; background: #f3f4f6; border: 2px solid #d1d5db; }
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.example-shape.square { }
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.example-shape.triangle { clip-path: polygon(50% 10%, 90% 90%, 10% 90%); }
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.example-shape.circle { border-radius: 50%; }
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.example-shape.rectangle { }
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.example-shape.star { clip-path: polygon(50% 8%, 61% 35%, 90% 38%, 66% 58%, 72% 86%, 50% 70%, 28% 86%, 34% 58%, 10% 38%, 39% 35%); }
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.example-shape.hexagon { clip-path: polygon(25% 5%, 75% 5%, 95% 50%, 75% 95%, 25% 95%, 5% 50%); }
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footer { text-align: center; color: #6b7280; padding: 24px 16px; }
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</style>
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</head>
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<body>
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<header>
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<h1>Rotation Symmetry Explorer</h1>
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<p>Learn about shapes that look the same when rotated!</p>
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</header>
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<main>
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<section class="intro">
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<h2>What is Rotation Symmetry?</h2>
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<p>A shape has rotation symmetry when it looks exactly the same after being rotated around its center. The number of times it matches as it rotates through 360° is called its <strong>order</strong>.</p>
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</section>
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<section class="explorer">
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<div class="shape-container">
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<div class="shape-stage">
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<canvas id="stage"></canvas>
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</div>
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</div>
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<div class="controls">
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<div>
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<label for="rotation-slider">Rotate Shape:</label>
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<div class="row">
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<input type="range" id="rotation-slider" min="0" max="360" value="0" />
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<span id="rotation-value" style="width:48px; text-align:right; font-weight:700;">0°</span>
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</div>
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</div>
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<div>
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<label for="shape-select">Choose Shape:</label>
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<select id="shape-select">
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<option value="square">Square (Order: 4)</option>
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<option value="triangle">Triangle (Order: 3)</option>
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<option value="circle">Circle (Order: ∞)</option>
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<option value="rectangle">Rectangle (Order: 2)</option>
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<option value="star">Star (Order: 5)</option>
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<option value="hexagon">Hexagon (Order: 6)</option>
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<option value="drawing">My drawing</option>
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</select>
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</div>
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<div class="row">
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<button id="animate-btn" class="btn primary">Animate Rotation</button>
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<button id="reset-btn" class="btn">Reset</button>
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</div>
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<div class="row" style="justify-content: space-between;">
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<label class="toggle"><input type="checkbox" id="tracing-toggle" checked /> Tracing paper</label>
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<label class="toggle"><input type="checkbox" id="draw-toggle" /> Draw mode</label>
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</div>
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<div class="row" id="pen-row" style="display:none;">
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<label for="pen-size">Pen size</label>
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<input type="range" id="pen-size" min="1" max="16" value="4" />
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<span id="pen-size-value" style="width:36px; text-align:right;">4px</span>
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<button id="clear-drawing" class="btn ghost">Clear drawing</button>
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</div>
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<div class="info">
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<h3>Symmetry Order: <span id="order-value">4</span></h3>
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<p id="shape-info">A square looks the same 4 times during a full rotation of 360°.</p>
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<p style="font-size:12px; color:#6b7280; margin-top:8px;">Tip: Watch the small dark dot on the shape. It is a <strong>reference point</strong> that shows how the shape turns.</p>
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</div>
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</div>
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</section>
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<section class="examples">
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<h2>Common Shapes with Rotation Symmetry</h2>
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<div class="shapes-grid">
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<div class="shape-item" data-shape="square">
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<div class="example-shape square"></div>
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<p>Square</p>
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</div>
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<div class="shape-item" data-shape="triangle">
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<div class="example-shape triangle"></div>
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<p>Triangle</p>
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</div>
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<div class="shape-item" data-shape="circle">
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<div class="example-shape circle"></div>
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<p>Circle</p>
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</div>
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<div class="shape-item" data-shape="rectangle">
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<div class="example-shape rectangle"></div>
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<p>Rectangle</p>
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</div>
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<div class="shape-item" data-shape="star">
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<div class="example-shape star"></div>
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<p>Star</p>
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</div>
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<div class="shape-item" data-shape="hexagon">
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<div class="example-shape hexagon"></div>
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<p>Hexagon</p>
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</div>
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</div>
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</section>
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</main>
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<footer>
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<p>Created for kids to learn about rotation symmetry | Made with HTML, CSS, and JavaScript</p>
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</footer>
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<script>
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// --- State ---
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const canvas = document.getElementById('stage');
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const slider = document.getElementById('rotation-slider');
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const rotationValue = document.getElementById('rotation-value');
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const shapeSelect = document.getElementById('shape-select');
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const orderValue = document.getElementById('order-value');
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const shapeInfo = document.getElementById('shape-info');
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const animateBtn = document.getElementById('animate-btn');
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const resetBtn = document.getElementById('reset-btn');
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const tracingToggle = document.getElementById('tracing-toggle');
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const drawToggle = document.getElementById('draw-toggle');
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const penRow = document.getElementById('pen-row');
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const penSizeInput = document.getElementById('pen-size');
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const penSizeValue = document.getElementById('pen-size-value');
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const clearDrawingBtn = document.getElementById('clear-drawing');
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const ctx = canvas.getContext('2d');
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let angle = 0; // degrees
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let shape = 'square';
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let tracing = true;
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let drawMode = false;
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let penDown = false;
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let penSize = 4;
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let strokes = []; // Array of arrays of points in center coords
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let animating = false;
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let rafId = null;
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let lastTs = 0;
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function setupCanvas() {
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const dpr = window.devicePixelRatio || 1;
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const rect = canvas.getBoundingClientRect();
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canvas.width = Math.round(rect.width * dpr);
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canvas.height = Math.round(rect.height * dpr);
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ctx.setTransform(dpr, 0, 0, dpr, 0, 0);
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}
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function getCenter() {
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return { cx: canvas.clientWidth / 2, cy: canvas.clientHeight / 2 };
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}
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function deg2rad(d) { return (d * Math.PI) / 180; }
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function makeShapePath() {
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const size = Math.min(canvas.clientWidth, canvas.clientHeight) * 0.32;
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switch (shape) {
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case 'square':
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return { type: 'poly', pts: [
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{x: -size, y: -size}, {x: size, y: -size}, {x: size, y: size}, {x: -size, y: size}
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]};
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case 'triangle':
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return { type: 'poly', pts: [
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{x: 0, y: -size}, {x: size, y: size}, {x: -size, y: size}
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]};
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case 'circle':
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return { type: 'circle', r: size };
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case 'rectangle': {
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const w = size * 1.8, h = size; // wider than tall
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return { type: 'poly', pts: [
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{x: -w, y: -h}, {x: w, y: -h}, {x: w, y: h}, {x: -w, y: h}
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]};
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}
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case 'star': {
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const pts = []; const spikes = 5; const outer = size; const inner = size * 0.45;
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for (let i = 0; i < spikes * 2; i++) {
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const r = (i % 2 === 0) ? outer : inner;
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const a = (i * Math.PI) / spikes - Math.PI / 2;
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pts.push({ x: r * Math.cos(a), y: r * Math.sin(a) });
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}
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return { type: 'poly', pts };
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}
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case 'hexagon': {
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const pts = []; const r = size;
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for (let i = 0; i < 6; i++) {
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const a = (i * Math.PI) / 3 - Math.PI / 2;
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pts.push({ x: r * Math.cos(a), y: r * Math.sin(a) });
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}
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return { type: 'poly', pts };
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}
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case 'drawing':
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return { type: 'strokes', strokes };
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}
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}
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function drawGrid(w, h) {
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ctx.save();
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ctx.clearRect(0, 0, w, h);
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ctx.lineWidth = 1; ctx.strokeStyle = '#e5e7eb';
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for (let x = 0; x < w; x += 40) { ctx.beginPath(); ctx.moveTo(x + 0.5, 0); ctx.lineTo(x + 0.5, h); ctx.stroke(); }
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for (let y = 0; y < h; y += 40) { ctx.beginPath(); ctx.moveTo(0, y + 0.5); ctx.lineTo(w, y + 0.5); ctx.stroke(); }
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ctx.restore();
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}
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function drawReference(cx, cy) {
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ctx.save();
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// center point
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ctx.fillStyle = '#ef4444';
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ctx.beginPath(); ctx.arc(cx, cy, 6, 0, Math.PI * 2); ctx.fill();
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// 0° reference line
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ctx.strokeStyle = '#2563eb'; ctx.lineWidth = 3; ctx.beginPath(); ctx.moveTo(cx, cy); ctx.lineTo(cx + 160, cy); ctx.stroke();
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// current angle line
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ctx.save(); ctx.translate(cx, cy); ctx.rotate(deg2rad(angle));
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ctx.strokeStyle = '#16a34a'; ctx.beginPath(); ctx.moveTo(0, 0); ctx.lineTo(160, 0); ctx.stroke(); ctx.restore();
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// angle arc
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const radius = 36; ctx.strokeStyle = '#6b7280'; ctx.lineWidth = 2; ctx.beginPath(); ctx.arc(cx, cy, radius, 0, deg2rad(angle), angle >= 0); ctx.stroke();
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// label
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ctx.fillStyle = '#111827'; ctx.font = 'bold 14px ui-sans-serif, system-ui'; ctx.fillText(Math.round(angle) + '°', cx + radius + 10, cy - 8);
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ctx.restore();
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}
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function drawPoly(pts) {
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if (!pts.length) return; ctx.beginPath(); ctx.moveTo(pts[0].x, pts[0].y); for (let i = 1; i < pts.length; i++) ctx.lineTo(pts[i].x, pts[i].y); ctx.closePath();
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}
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function drawStrokesSet(s, lw) {
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ctx.lineJoin = 'round'; ctx.lineCap = 'round';
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for (const stroke of s) {
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if (stroke.length < 2) continue; ctx.beginPath(); ctx.moveTo(stroke[0].x, stroke[0].y); for (let i = 1; i < stroke.length; i++) ctx.lineTo(stroke[i].x, stroke[i].y); ctx.lineWidth = lw; ctx.stroke();
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}
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}
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function drawShapeWithOptions(cx, cy, color, alpha, atAngleDeg, showMarker) {
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const path = makeShapePath();
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ctx.save(); ctx.translate(cx, cy); ctx.rotate(deg2rad(atAngleDeg)); ctx.globalAlpha = alpha; ctx.strokeStyle = color; ctx.fillStyle = 'rgba(0,0,0,0)';
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if (path.type === 'poly') {
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drawPoly(path.pts); ctx.lineWidth = 4; ctx.stroke();
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if (showMarker && path.pts.length) { const p = path.pts[0]; ctx.fillStyle = '#111827'; ctx.beginPath(); ctx.arc(p.x, p.y, 6, 0, Math.PI * 2); ctx.fill(); }
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} else if (path.type === 'circle') {
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ctx.beginPath(); ctx.arc(0, 0, path.r, 0, Math.PI * 2); ctx.lineWidth = 4; ctx.stroke(); if (showMarker) { ctx.fillStyle = '#111827'; ctx.beginPath(); ctx.arc(path.r, 0, 6, 0, Math.PI * 2); ctx.fill(); }
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} else if (path.type === 'strokes') {
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ctx.lineWidth = penSize; drawStrokesSet(path.strokes, penSize);
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if (showMarker && path.strokes.length && path.strokes[0].length) { const p = path.strokes[0][0]; ctx.fillStyle = '#111827'; ctx.beginPath(); ctx.arc(p.x, p.y, 6, 0, Math.PI * 2); ctx.fill(); }
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}
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ctx.restore();
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}
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function draw() {
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const w = canvas.clientWidth, h = canvas.clientHeight; const { cx, cy } = getCenter();
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drawGrid(w, h); drawReference(cx, cy);
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if (tracing) drawShapeWithOptions(cx, cy, '#6b7280', 0.35, 0, true); // faint original at 0°
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drawShapeWithOptions(cx, cy, '#111827', 1, angle, true); // active rotated shape
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}
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// --- Drawing (pen) ---
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function toLocal(clientX, clientY) {
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const rect = canvas.getBoundingClientRect(); const x = clientX - rect.left; const y = clientY - rect.top; const { cx, cy } = getCenter(); return { x: x - cx, y: y - cy };
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}
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canvas.addEventListener('pointerdown', (e) => {
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if (!drawMode) return; const p = toLocal(e.clientX, e.clientY); penDown = true; strokes.push([p]); if (shape !== 'drawing') { shape = 'drawing'; shapeSelect.value = 'drawing'; updateInfo(); }
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draw();
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});
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canvas.addEventListener('pointermove', (e) => {
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if (!drawMode || !penDown) return; const p = toLocal(e.clientX, e.clientY); const last = strokes[strokes.length - 1]; last.push(p); draw();
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});
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function endStroke() { penDown = false; }
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canvas.addEventListener('pointerup', endStroke);
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canvas.addEventListener('pointerleave', endStroke);
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// --- UI events ---
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slider.addEventListener('input', () => { angle = Number(slider.value); rotationValue.textContent = Math.round(angle) + '°'; draw(); });
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shapeSelect.addEventListener('change', () => { shape = shapeSelect.value; updateInfo(); draw(); });
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animateBtn.addEventListener('click', () => { animating = !animating; animateBtn.textContent = animating ? 'Stop' : 'Animate Rotation'; if (animating) { lastTs = performance.now(); rafId = requestAnimationFrame(loop); } else if (rafId) { cancelAnimationFrame(rafId); } });
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resetBtn.addEventListener('click', () => { angle = 0; slider.value = '0'; rotationValue.textContent = '0°'; tracing = true; tracingToggle.checked = true; drawMode = false; drawToggle.checked = false; canvas.classList.remove('drawing'); strokes = []; shape = 'square'; shapeSelect.value = 'square'; penSize = 4; penSizeInput.value = '4'; penSizeValue.textContent = '4px'; updateInfo(); draw(); });
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tracingToggle.addEventListener('change', () => { tracing = tracingToggle.checked; draw(); });
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drawToggle.addEventListener('change', () => { drawMode = drawToggle.checked; penRow.style.display = drawMode ? 'flex' : 'none'; canvas.classList.toggle('drawing', drawMode); if (drawMode) { shape = 'drawing'; shapeSelect.value = 'drawing'; updateInfo(); } draw(); });
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penSizeInput.addEventListener('input', () => { penSize = Number(penSizeInput.value); penSizeValue.textContent = penSize + 'px'; draw(); });
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clearDrawingBtn.addEventListener('click', () => { strokes = []; draw(); });
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document.querySelectorAll('.shape-item').forEach(card => {
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card.addEventListener('click', () => { const val = card.getAttribute('data-shape'); shape = val; shapeSelect.value = val; if (val !== 'drawing') { drawMode = false; drawToggle.checked = false; penRow.style.display = 'none'; canvas.classList.remove('drawing'); } updateInfo(); draw(); });
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});
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// --- Animate loop ---
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function loop(ts) {
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const dt = Math.min(32, ts - lastTs); lastTs = ts; // ms
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angle = (angle + (dt * 0.12)) % 360; // ~43° per second
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slider.value = String(angle); rotationValue.textContent = Math.round(angle) + '°';
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draw();
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if (animating) rafId = requestAnimationFrame(loop);
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}
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// --- Info / order ---
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function getOrder(s) {
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switch (s) {
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case 'square': return 4;
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case 'triangle': return 3;
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case 'circle': return '∞';
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case 'rectangle': return 2;
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case 'star': return 5; // regular 5-point star
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case 'hexagon': return 6;
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case 'drawing': return '?';
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}
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}
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function updateInfo() {
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const ord = getOrder(shape); orderValue.textContent = ord;
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const textMap = {
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square: 'A square looks the same 4 times during a full rotation of 360°.',
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triangle: 'An equilateral triangle matches itself 3 times in 360°.',
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circle: 'A circle looks the same at any angle, so its order is infinite.',
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rectangle: 'A rectangle matches itself 2 times in 360° (every 180°).',
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star: 'A 5-point star matches itself 5 times in 360°.',
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hexagon: 'A regular hexagon matches itself 6 times in 360°.',
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drawing: 'Draw your own shape. The order depends on your design.'
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};
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shapeInfo.textContent = textMap[shape];
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}
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// --- Init ---
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window.addEventListener('resize', () => { setupCanvas(); draw(); });
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setupCanvas(); updateInfo(); draw();
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</script>
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</body>
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</html>
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