js实现闪电

使用Canvas绘制闪电效果

通过HTML5的Canvas API可以动态生成闪电效果。以下是一个简单的实现方法：

const canvas = document.getElementById('lightningCanvas');
const ctx = canvas.getContext('2d');

function drawLightning() {
    ctx.clearRect(0, 0, canvas.width, canvas.height);
    ctx.beginPath();

    const startX = Math.random() * canvas.width;
    const startY = 0;
    ctx.moveTo(startX, startY);

    let currentX = startX;
    let currentY = startY;

    while (currentY < canvas.height) {
        const nextX = currentX + (Math.random() - 0.5) * 30;
        const nextY = currentY + Math.random() * 20 + 10;
        ctx.lineTo(nextX, nextY);
        currentX = nextX;
        currentY = nextY;
    }

    ctx.strokeStyle = 'rgba(255, 255, 255, 0.7)';
    ctx.lineWidth = 2;
    ctx.stroke();

    // 添加闪光效果
    ctx.fillStyle = 'rgba(255, 255, 255, 0.2)';
    ctx.fillRect(0, 0, canvas.width, canvas.height);
}

setInterval(drawLightning, 300);

使用CSS动画创建闪电效果

纯CSS也可以模拟闪电效果，适合简单的视觉展示：

<style>
.lightning {
    position: absolute;
    width: 2px;
    height: 100%;
    background: white;
    left: 50%;
    box-shadow: 0 0 10px 2px white;
    opacity: 0;
    animation: lightning 4s infinite;
}

@keyframes lightning {
    0% { opacity: 0; }
    1% { opacity: 0.8; }
    2% { opacity: 0; }
    8% { opacity: 0; }
    9% { opacity: 0.5; }
    10% { opacity: 0; }
    100% { opacity: 0; }
}
</style>

<div class="lightning"></div>

使用Three.js创建3D闪电

对于更复杂的3D场景，可以使用Three.js库：

import * as THREE from 'three';

const scene = new THREE.Scene();
const camera = new THREE.PerspectiveCamera(75, window.innerWidth / window.innerHeight, 0.1, 1000);
const renderer = new THREE.WebGLRenderer();

function createLightning() {
    const points = [];
    points.push(new THREE.Vector3(0, 10, 0));

    for (let i = 1; i < 10; i++) {
        points.push(new THREE.Vector3(
            points[i-1].x + (Math.random() - 0.5) * 2,
            points[i-1].y - Math.random() * 3,
            0
        ));
    }

    const geometry = new THREE.BufferGeometry().setFromPoints(points);
    const material = new THREE.LineBasicMaterial({ color: 0x00ffff });
    const lightning = new THREE.Line(geometry, material);
    scene.add(lightning);

    setTimeout(() => scene.remove(lightning), 100);
}

setInterval(createLightning, 1000);

优化闪电效果

为了更真实的闪电效果，可以考虑以下优化：

• 添加分支闪电
• 实现渐变消失效果
• 添加环境光变化
• 使用粒子系统增强视觉效果

每种方法适用于不同场景，Canvas适合2D游戏，CSS适合简单页面效果，Three.js适合3D场景。根据需求选择合适方案。