HTML5canvas实现的流体动力学模拟动画效果源码.zip资源-CSDN文库

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HTML5 Canvas是一个强大的Web图形接口，它允许开发者在网页上绘制矢量图形和动画，而无需依赖外部插件。这个“HTML5 Canvas实现的流体动力学模拟动画效果源码”压缩包提供了一种利用Canvas API来模拟真实世界中的流体动力学行为的示例。以下是对这个源码包中可能包含的知识点的详细解释： 1. HTML5 Canvas基础： - `canvas`元素：HTML5的新特性，用于在网页上进行动态图形绘制。 - `getContext('2d')`：获取2D渲染上下文，是进行绘图操作的主要接口。 - 基本绘图方法：如`fillRect()`、`strokeRect()`、`beginPath()`、`moveTo()`、`lineTo()`等，用于绘制矩形、线条和其他形状。 2. 流体动力学概念： - Navier-Stokes方程：描述流体运动的基本方程组，包括动量守恒和连续性方程。 - 数值模拟：由于Navier-Stokes方程的复杂性，通常通过离散化和数值解法来近似求解。 - Euler方法或Runge-Kutta方法：常用的数值积分方法，用于时间步进计算流体的动态变化。 3. 流体模拟算法： - 布朗运动（热力学）：随机粒子运动，模拟流体中的微小波动。 - 分子动力学：基于牛顿运动定律模拟大量分子的行为。 - SPH（Smoothed Particle Hydrodynamics）：无网格方法，将流体视为粒子集合，通过加权平均计算流体性质。 - FFT（快速傅里叶变换）：用于计算速度场的扩散和粘性效应，加速计算过程。 4. Canvas动画原理： - requestAnimationFrame()：用于在下一次重绘之前调用指定的函数，创建流畅的动画效果。 - 渲染循环：不断地更新和绘制帧，以形成连续的动画。 5. 实时交互与性能优化： - 用户交互处理：响应鼠标或触摸事件，改变流体参数或行为。 - GPU加速：利用WebGL进行GPU渲染，提高大规模计算性能。 - 隔离计算区域：仅更新和绘制屏幕可见部分，提高效率。 6. 源码结构分析： - 主文件：通常包含初始化设置、动画循环、事件处理等核心逻辑。 - 数据结构：可能有表示流体状态的数据对象，如速度、密度、压力等。 - 辅助函数：如边界条件处理、物理模型计算等。 7. 调试与学习资源： - 使用浏览器的开发者工具检查和调试Canvas绘图代码。 - MDN Web Docs：学习HTML5 Canvas API的官方文档。 - Stack Overflow：寻找问题解决方案和学习其他开发者的经验。这个源码实例对于理解如何利用HTML5 Canvas实现复杂物理现象的模拟具有很高的教育价值。开发者可以通过分析和修改代码，深入学习流体动力学模拟以及Canvas动画的实现技巧。

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HTML5 canvas实现的流体动力学模拟动画效果源码.zip （3个子文件）

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index.html 11KB

stats.min.js 2KB

dat.gui.min.js 44KB

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"> <head> <meta http-equiv="Content-Type" content="text/html; charset=utf-8" /> <title>HTML5 Canvas流体动力学模拟动画</title> <style> body { background: black; } </style> </head> <body>  <script src='js/dat.gui.min.js'></script> <script src='js/stats.min.js'></script> <script> const row = 64; const col = 64; const width = 8; const height = 8; let control = { diff: 1, visc: 1, fadeOutDensityRate: 0.01, fadeOutVelocityRate: 0.01, drawDensity: true, emitDensity: true, emitDensityScale: 50, emitDensityExpand: 0, drawVelocity: false, drawVelocityScale: 2, emitVelocity: true, emitVelocityScale: 256, emitVelocityExpand: 5, }; let gui = new dat.GUI(); gui.add(control, 'diff'); gui.add(control, 'visc'); gui.add(control, 'fadeOutDensityRate', 0, 1); gui.add(control, 'fadeOutVelocityRate', 0, 1); gui.add(control, 'drawDensity'); gui.add(control, 'emitDensity'); gui.add(control, 'emitDensityExpand', 0, 5).step(1); gui.add(control, 'emitDensityScale'); gui.add(control, 'drawVelocityScale'); gui.add(control, 'drawVelocity'); gui.add(control, 'emitVelocity'); gui.add(control, 'emitVelocityExpand', 0, 5).step(1); gui.add(control, 'emitVelocityScale'); class FluidDynamicSolver { constructor(width = 32, height = 32) { this.width = width; this.height = height; // expand 2 for boundaries this.size = (this.width + 2) * (this.height + 2); this.innerSize = this.width * this.height; // init this.u_prev = this.reset([]); this.v_prev = this.reset([]); this.d_prev = this.reset([]); this.u_next = this.reset([]); this.v_next = this.reset([]); this.d_next = this.reset([]); } idx(x, y) { return x + y * (this.width + 2) } addSource(source, target, dt) { for (let i = 0; i < this.size; i++) { target[i] += source[i] * dt; } } diffuse(prev, next, diff, dt, boundaryFlag) { const a = dt * diff; // do 20 iterations of Gauss-Seidel relaxation for (let k = 0; k < 20; k++) { // ignore the boundaries for (let i = 1; i <= this.width; i++) { for (let j = 1; j <= this.height; j++) { next[this.idx(i, j)] = (prev[this.idx(i, j)] + a * ( next[this.idx(i - 1, j)] + next[this.idx(i + 1, j)] + next[this.idx(i, j - 1)] + next[this.idx(i, j + 1)])) / (1 + 4 * a); } } this.setBoundary(next, boundaryFlag); } } advection(prev, next, u_next, v_next, dt, boundaryFlag) { const d = dt; for (let i = 1; i <= this.width; i++) { for (let j = 1; j <= this.height; j++) { const x = Math.min(Math.max(0.5, i - d * u_next[this.idx(i, j)]), this.width + 0.5); const y = Math.min(Math.max(0.5, j - d * v_next[this.idx(i, j)]), this.height + 0.5); const i0 = x | 0; const j0 = y | 0; const i1 = i0 + 1; const j1 = j0 + 1; const s1 = x - i0; const s0 = 1 - s1; const t1 = y - j0; const t0 = 1 - t1; next[this.idx(i, j)] = s0 * (t0 * prev[this.idx(i0, j0)] + t1 * prev[this.idx(i0, j1)]) + s1 * (t0 * prev[this.idx(i1, j0)] + t1 * prev[this.idx(i1, j1)]); } } this.setBoundary(next, boundaryFlag); } setBoundary(target, boundaryFlag) { for (let i = 1; i <= this.width; i++) { target[this.idx(i, 0)] = (boundaryFlag === 2 ? -1 : 1) * target[this.idx(i, 1)]; target[this.idx(i, this.height + 1)] = (boundaryFlag === 2 ? -1 : 1) * target[this.idx(i, this.height)]; } for (let j = 1; j <= this.height; j++) { target[this.idx(0, j)] = (boundaryFlag === 1 ? -1 : 1) * target[this.idx(1, j)]; target[this.idx(this.width + 1, j)] = (boundaryFlag === 1 ? -1 : 1) * target[this.idx(this.width, j)]; } target[this.idx(0, 0)] = (target[this.idx(0, 1)] + target[this.idx(1, 0)]) / 2; target[this.idx(0, this.height + 1)] = (target[this.idx(0, this.height)] + target[this.idx(1, this.height + 1)]) / 2; target[this.idx(this.width + 1, 0)] = (target[this.idx(this.width, 0)] + target[this.idx(this.width + 1, 1)]) / 2; target[this.idx(this.width + 1, this.height + 1)] = (target[this.idx(0, this.height)] + target[this.idx(1, this.height + 1)]) / 2; } stepDensity(diff, dt) { this.addSource(this.d_prev, this.d_next, dt); [this.d_prev, this.d_next] = [this.d_next, this.d_prev]; this.diffuse(this.d_prev, this.d_next, diff, dt, 0); [this.d_prev, this.d_next] = [this.d_next, this.d_prev]; this.advection(this.d_prev, this.d_next, this.u_next, this.v_next, dt, 0); } stepVelocity(visc, dt) { this.addSource(this.u_prev, this.u_next, dt); this.addSource(this.v_prev, this.v_next, dt); [this.u_prev, this.u_next] = [this.u_next, this.u_prev]; this.diffuse(this.u_prev, this.u_next, visc, dt, 1); [this.v_prev, this.v_next] = [this.v_next, this.v_prev]; this.diffuse(this.v_prev, this.v_next, visc, dt, 2); this.project(this.u_prev, this.v_prev, this.u_next, this.v_next); [this.u_prev, this.u_next] = [this.u_next, this.u_prev]; [this.v_prev, this.v_next] = [this.v_next, this.v_prev]; this.advection(this.u_prev, this.u_next, this.u_prev, this.v_prev, dt, 1); this.advection(this.v_prev, this.v_next, this.u_prev, this.v_prev, dt, 2); this.project(this.u_prev, this.v_prev, this.u_next, this.v_next); } project(p, div, u, v) { const h = 1 / this.width; for (let i = 1; i <= this.width; i++) { for (let j = 1; j <= this.height; j++) { div[this.idx(i, j)] = -0.5 * h * ( u[this.idx(i + 1, j)] - u[this.idx(i - 1, j)] + v[this.idx(i, j + 1)] - v[this.idx(i, j - 1)]); p[this.idx(i, j)] = 0; } } this.setBoundary(div, 0); this.setBoundary(p, 0); // do 20 iterations of Gauss-Seidel relaxation for (let k = 0; k < 20; k++) { // ignore the boundaries for (let i = 1; i <= this.width; i++) { for (let j = 1; j <= this.height; j++) { p[this.idx(i, j)] = (div[this.idx(i, j)] + ( p[this.idx(i - 1, j)] + p[this.idx(i + 1, j)] + p[this.idx(i, j - 1)] + p[this.idx(i, j + 1)])) / 4; } } this.setBoundary(p, 0); } for (let i = 1; i <= this.width; i++) { for (let j = 1; j <= this.height; j++) { u[this.idx(i, j)] -= 0.5 * (p[this.idx(i + 1, j)] - p[this.idx(i - 1, j)]) / h; v[this.idx(i, j)] -= 0.5 * (p[this.idx(i, j + 1)] - p[this.idx(i, j - 1)]) / h; } } this.setBoundary(u, 1); this.setBoundary(v, 2); } set(target, source) { for (let i = 0; i < this.size; i++) { target[i] = source[i]; } return target; } reset(target, value = 0) { for (let i = 0; i < this.size; i++) { target[i] = value; } return target; } fadeOut(target, rate) { for (let i = 0; i < this.size; i++) { target[i] *= rate; } return target; } } let fluid = new FluidDynamicSolver(col, row); let dt = 1 / 60; let d_ui = fluid.reset([]); let u_ui = fluid.reset([]); let v_ui = fluid.reset([]); let canvas = document.createElement('canvas'); canvas.width = col * width; canvas.height = row * height; let lastX, lastY; function pointerMoveHandle(x, y) { let tileX = (x / width | 0) + 1; let tileY = (y / height | 0) + 1; if (lastX !== undefined) { let deltaX = x - lastX; let deltaY = y - lastY; if (control.emitDensity) { for (let i = Math.max(1, tileX - control.emi

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