您是否曾经被抽象的粒子动画迷住过？这些流动的动态视觉效果可以通过使用纯 JavaScript 和 HTML canvas 元素的极其简单的技术来实现。在本文中，我们将分解创建一个流场的过程，该流场可以为数千个粒子提供动画，让它们自然运动。
首先，我们需要三个文件：一个用于设置画布的 HTML 文件、一个用于样式设置的 CSS 文件以及一个用于处理逻辑的 JavaScript 文件。
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>Flow Fields</title>
<link rel="stylesheet" href="styles.css">
</head>
<body>
<canvas id="canvas1"></canvas>
<script src="script.js"></script>
</body>
</html>
让我们添加一个简单的样式，为画布提供黑色背景，并确保删除所有内边距和边距。
* {
margin: 0;
padding: 0;
box-sizing: border-box;
}
canvas {
background-color: black;
}
Particle类是动画的核心所在。每个粒子在画布上移动，留下其过去位置的痕迹，创造流动的效果。
class Particle {
constructor(effect) {
this.effect = effect;
this.x = Math.floor(Math.random() * this.effect.width);
this.y = Math.floor(Math.random() * this.effect.height);
this.speedModifier = Math.floor(Math.random() * 5 + 1);
this.history = [{ x: this.x, y: this.y }];
this.maxLength = Math.floor(Math.random() * 200 + 10);
this.timer = this.maxLength * 2;
this.colors = ['#4C026B', '#8E0E00', '#9D0208', '#BA1A1A', '#730D9E'];
this.color = this.colors[Math.floor(Math.random() * this.colors.length)];
}
draw(context) {
context.beginPath();
context.moveTo(this.history[0].x, this.history[0].y);
for (let i = 1; i < this.history.length; i++) {
context.lineTo(this.history[i].x, this.history[i].y);
}
context.strokeStyle = this.color;
context.stroke();
}
update() {
this.timer--;
if (this.timer >= 1) {
let x = Math.floor(this.x / this.effect.cellSize);
let y = Math.floor(this.y / this.effect.cellSize);
let index = y * this.effect.cols + x;
let angle = this.effect.flowField[index];
this.speedX = Math.cos(angle);
this.speedY = Math.sin(angle);
this.x += this.speedX * this.speedModifier;
this.y += this.speedY * this.speedModifier;
this.history.push({ x: this.x, y: this.y });
if (this.history.length > this.maxLength) {
this.history.shift();
}
} else if (this.history.length > 1) {
this.history.shift();
} else {
this.reset();
}
}
reset() {
this.x = Math.floor(Math.random() * this.effect.width);
this.y = Math.floor(Math.random() * this.effect.height);
this.history = [{ x: this.x, y: this.y }];
this.timer = this.maxLength * 2;
}
}
Effect 类处理粒子的创建和流场本身，它控制粒子的运动。
class Effect {
constructor(canvas) {
this.canvas = canvas;
this.width = this.canvas.width;
this.height = this.canvas.height;
this.particles = [];
this.numberOfParticles = 3000;
this.cellSize = 20;
this.flowField = [];
this.curve = 5;
this.zoom = 0.12;
this.debug = true;
this.init();
}
init() {
this.rows = Math.floor(this.height / this.cellSize);
this.cols = Math.floor(this.width / this.cellSize);
for (let y = 0; y < this.rows; y++) {
for (let x = 0; x < this.cols; x++) {
let angle = (Math.cos(x * this.zoom) + Math.sin(y * this.zoom)) * this.curve;
this.flowField.push(angle);
}
}
for (let i = 0; i < this.numberOfParticles; i++) {
this.particles.push(new Particle(this));
}
}
drawGrid(context) {
context.save();
context.strokeStyle = 'white';
context.lineWidth = 0.3;
for (let c = 0; c < this.cols; c++) {
context.beginPath();
context.moveTo(c * this.cellSize, 0);
context.lineTo(c * this.cellSize, this.height);
context.stroke();
}
for (let r = 0; r < this.rows; r++) {
context.beginPath();
context.moveTo(0, r * this.cellSize);
context.lineTo(this.width, r * this.cellSize);
context.stroke();
}
context.restore();
}
render(context) {
if (this.debug) this.drawGrid(context);
this.particles.forEach(particle => {
particle.draw(context);
particle.update();
});
}
}
为了让一切正常工作，我们需要一个动画循环来不断清除画布并重新渲染粒子：
const effect = new Effect(canvas);
function animate() {
ctx.clearRect(0, 0, canvas.width, canvas.height);
effect.render(ctx);
requestAnimationFrame(animate);
}
animate();
通过分解 Particle 和 Effect 类，我们仅使用普通 JavaScript 创建了流体和动态流场动画。 HTML 画布的简单性与 JavaScript 的三角函数相结合，使我们能够构建这些令人着迷的视觉效果。
随意使用粒子数、颜色或流场公式来创建您自己的独特效果！
以上是流场屏幕的详细内容。更多信息请关注PHP中文网其他相关文章！
