artifacts/pendulum-2.html (173 lines of code) (raw):
<!doctype html>
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<html lang="en">
<head>
<meta charset="UTF-8" />
<meta name="viewport" content="width=device-width, initial-scale=1.0" />
<title>Double Pendulum Simulation</title>
<style>
body {
margin: 0;
overflow: hidden;
font-family: sans-serif;
background-color: #f0f0f0;
}
canvas {
background-color: #fff;
display: block;
}
.container {
display: flex;
flex-direction: column;
align-items: center;
justify-content: center;
height: 100vh;
}
.controls {
background-color: rgba(240, 240, 240, 0.8);
padding: 20px;
border-radius: 5px;
margin-bottom: 20px;
}
.controls label,
.controls input {
display: block;
margin-bottom: 10px;
}
.controls button {
padding: 8px 16px;
background-color: #4caf50;
color: white;
border: none;
border-radius: 5px;
cursor: pointer;
}
</style>
</head>
<body>
<div class="container">
<div class="controls">
<label for="length1">Length 1:</label>
<input type="range" id="length1" min="10" max="150" value="100" />
<label for="length2">Length 2:</label>
<input type="range" id="length2" min="10" max="150" value="100" />
<label for="mass1">Mass 1:</label>
<input type="range" id="mass1" min="1" max="10" value="5" />
<label for="mass2">Mass 2:</label>
<input type="range" id="mass2" min="1" max="10" value="5" />
<button id="resetButton">Reset</button>
</div>
<canvas id="canvas" width="800" height="600"></canvas>
</div>
<script>
const canvas = document.getElementById("canvas");
const ctx = canvas.getContext("2d");
const length1Slider = document.getElementById("length1");
const length2Slider = document.getElementById("length2");
const mass1Slider = document.getElementById("mass1");
const mass2Slider = document.getElementById("mass2");
const resetButton = document.getElementById("resetButton");
let length1 = length1Slider.value;
let length2 = length2Slider.value;
let mass1 = mass1Slider.value;
let mass2 = mass2Slider.value;
let angle1 = Math.PI / 2;
let angle2 = Math.PI / 2;
let angularVelocity1 = 0;
let angularVelocity2 = 0;
let gravity = 1;
function drawPendulum() {
const x1 = length1 * Math.sin(angle1);
const y1 = length1 * Math.cos(angle1);
const x2 = x1 + length2 * Math.sin(angle2);
const y2 = y1 + length2 * Math.cos(angle2);
ctx.clearRect(0, 0, canvas.width, canvas.height);
// Draw lines
ctx.beginPath();
ctx.moveTo(canvas.width / 2, canvas.height / 2);
ctx.lineTo(canvas.width / 2 + x1, canvas.height / 2 + y1);
ctx.lineTo(canvas.width / 2 + x2, canvas.height / 2 + y2);
ctx.strokeStyle = "black";
ctx.lineWidth = 2;
ctx.stroke();
// Draw bobs
ctx.beginPath();
ctx.arc(
canvas.width / 2 + x1,
canvas.height / 2 + y1,
mass1 * 5,
0,
Math.PI * 2,
);
ctx.fill();
ctx.beginPath();
ctx.arc(
canvas.width / 2 + x2,
canvas.height / 2 + y2,
mass2 * 5,
0,
Math.PI * 2,
);
ctx.fill();
}
function updatePendulum() {
// Calculate accelerations using the double pendulum equations of motion
const num1 =
-gravity * (2 * mass1 + mass2) * Math.sin(angle1) -
mass2 * gravity * Math.sin(angle1 - 2 * angle2);
const num2 = -2 * Math.sin(angle1 - angle2) * mass2;
const num3 =
angularVelocity2 * angularVelocity2 * length2 +
angularVelocity1 *
angularVelocity1 *
length1 *
Math.cos(angle1 - angle2);
const den =
length1 *
(2 * mass1 + mass2 - mass2 * Math.cos(2 * angle1 - 2 * angle2));
const angularAcceleration1 = (num1 + num2 * num3) / den;
const num4 = 2 * Math.sin(angle1 - angle2);
const num5 =
angularVelocity1 * angularVelocity1 * length1 * (mass1 + mass2);
const num6 =
gravity * (mass1 + mass2) * Math.cos(angle1) +
angularVelocity2 *
angularVelocity2 *
length2 *
mass2 *
Math.cos(angle1 - angle2);
const den2 =
length2 *
(2 * mass1 + mass2 - mass2 * Math.cos(2 * angle1 - 2 * angle2));
const angularAcceleration2 = (num4 * (num5 + num6)) / den2;
// Update angular velocities and angles
angularVelocity1 += angularAcceleration1;
angularVelocity2 += angularAcceleration2;
angle1 += angularVelocity1;
angle2 += angularVelocity2;
// Apply damping
angularVelocity1 *= 0.999;
angularVelocity2 *= 0.999;
drawPendulum();
requestAnimationFrame(updatePendulum);
}
function resetSimulation() {
angle1 = Math.PI / 2;
angle2 = Math.PI / 2;
angularVelocity1 = 0;
angularVelocity2 = 0;
}
length1Slider.addEventListener(
"input",
() => (length1 = length1Slider.value),
);
length2Slider.addEventListener(
"input",
() => (length2 = length2Slider.value),
);
mass1Slider.addEventListener("input", () => (mass1 = mass1Slider.value));
mass2Slider.addEventListener("input", () => (mass2 = mass2Slider.value));
resetButton.addEventListener("click", resetSimulation);
updatePendulum();
</script>
</body>
</html>