artifacts/pendulum-1.html (138 lines of code) (raw):
<!doctype html>
<!--
Copyright 2024 Google LLC
Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at
http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
-->
<html lang="en">
<head>
<meta charset="UTF-8" />
<meta name="viewport" content="width=device-width, initial-scale=1.0" />
<title>Two-Pendulum Simulation</title>
<style>
body {
margin: 0;
font-family: sans-serif;
overflow: hidden;
display: flex;
flex-direction: column;
align-items: center;
justify-content: center;
height: 100vh;
background-color: #f0f0f0;
}
canvas {
background-color: #fff;
border: 1px solid #ccc;
}
.controls {
display: flex;
flex-direction: column;
margin-top: 20px;
}
.controls label {
margin-bottom: 5px;
}
.controls input {
width: 100px;
margin-bottom: 10px;
}
</style>
</head>
<body>
<h1>Two-Pendulum Simulation</h1>
<canvas id="canvas" width="500" height="500"></canvas>
<div class="controls">
<label for="length1">Length 1:</label>
<input type="number" id="length1" value="150" />
<label for="mass1">Mass 1:</label>
<input type="number" id="mass1" value="10" />
<label for="length2">Length 2:</label>
<input type="number" id="length2" value="150" />
<label for="mass2">Mass 2:</label>
<input type="number" id="mass2" value="10" />
<button id="resetButton">Reset</button>
</div>
<script>
const canvas = document.getElementById("canvas");
const ctx = canvas.getContext("2d");
const length1Input = document.getElementById("length1");
const mass1Input = document.getElementById("mass1");
const length2Input = document.getElementById("length2");
const mass2Input = document.getElementById("mass2");
const resetButton = document.getElementById("resetButton");
let length1 = parseFloat(length1Input.value);
let mass1 = parseFloat(mass1Input.value);
let length2 = parseFloat(length2Input.value);
let mass2 = parseFloat(mass2Input.value);
let angle1 = Math.PI / 2;
let angle2 = Math.PI / 2;
let velocity1 = 0;
let velocity2 = 0;
let gravity = 1;
let animationFrameId;
function draw() {
ctx.clearRect(0, 0, canvas.width, canvas.height);
const x1 = canvas.width / 2 + 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.beginPath();
ctx.moveTo(canvas.width / 2, 0);
ctx.lineTo(x1, y1);
ctx.strokeStyle = "black";
ctx.lineWidth = 2;
ctx.stroke();
ctx.beginPath();
ctx.moveTo(x1, y1);
ctx.lineTo(x2, y2);
ctx.stroke();
ctx.beginPath();
ctx.arc(x1, y1, mass1, 0, Math.PI * 2);
ctx.fillStyle = "red";
ctx.fill();
ctx.beginPath();
ctx.arc(x2, y2, mass2, 0, Math.PI * 2);
ctx.fillStyle = "blue";
ctx.fill();
}
function update() {
const num1 = -gravity * (2 * mass1 + mass2) * Math.sin(angle1);
const num2 = -mass2 * gravity * Math.sin(angle1 - 2 * angle2);
const num3 = -2 * Math.sin(angle1 - angle2) * mass2;
const num4 =
velocity2 * velocity2 * length2 +
velocity1 * velocity1 * length1 * Math.cos(angle1 - angle2);
const den =
length1 *
(2 * mass1 + mass2 - mass2 * Math.cos(2 * angle1 - 2 * angle2));
const acceleration1 = (num1 + num2 + num3 * num4) / den;
const num5 = 2 * Math.sin(angle1 - angle2);
const num6 = velocity1 * velocity1 * length1 * (mass1 + mass2);
const num7 = gravity * (mass1 + mass2) * Math.cos(angle1);
const num8 =
velocity2 * velocity2 * length2 * mass2 * Math.cos(angle1 - angle2);
const den2 =
length2 *
(2 * mass1 + mass2 - mass2 * Math.cos(2 * angle1 - 2 * angle2));
const acceleration2 = (num5 * (num6 + num7 + num8)) / den2;
velocity1 += acceleration1;
velocity2 += acceleration2;
angle1 += velocity1;
angle2 += velocity2;
draw();
animationFrameId = requestAnimationFrame(update);
}
function resetSimulation() {
cancelAnimationFrame(animationFrameId);
length1 = parseFloat(length1Input.value);
mass1 = parseFloat(mass1Input.value);
length2 = parseFloat(length2Input.value);
mass2 = parseFloat(mass2Input.value);
angle1 = Math.PI / 2;
angle2 = Math.PI / 2;
velocity1 = 0;
velocity2 = 0;
draw();
update();
}
resetButton.addEventListener("click", resetSimulation);
resetSimulation();
</script>
</body>
</html>