第十二節:粒子系統:海量點渲染
引言
粒子系統是創造動態視覺效果的神器,從漫天繁星到熊熊火焰,從魔法特效到數據可視化,都離不開粒子技術。Three.js提供了強大的粒子渲染能力,可輕松處理百萬級粒子。本文將深入解析粒子系統核心原理,并通過Vue3實現交互式粒子編輯器,帶你掌握微觀世界的創造藝術。
1. 粒子系統基礎
1.1 核心組件
1.2 創建流程
// 1. 創建幾何體(存儲粒子位置)
const geometry = new THREE.BufferGeometry();// 2. 設置頂點數據
const positions = new Float32Array(1000 * 3); // 1000個粒子
geometry.setAttribute('position', new THREE.BufferAttribute(positions, 3));// 3. 創建材質
const material = new THREE.PointsMaterial({color: 0xffffff,size: 0.1,
});// 4. 創建粒子系統
const particles = new THREE.Points(geometry, material);
scene.add(particles);
2. 基礎粒子效果
2.1 靜態星空
<script setup>
import { onMounted } from 'vue';
import * as THREE from 'three';function createStars() {const starCount = 10000;const geometry = new THREE.BufferGeometry();// 生成隨機位置const positions = new Float32Array(starCount * 3);for (let i = 0; i < starCount * 3; i += 3) {positions[i] = (Math.random() - 0.5) * 2000; // xpositions[i+1] = (Math.random() - 0.5) * 2000; // ypositions[i+2] = (Math.random() - 0.5) * 2000; // z}geometry.setAttribute('position', new THREE.BufferAttribute(positions, 3));// 創建材質const material = new THREE.PointsMaterial({color: 0xffffff,size: 0.7,sizeAttenuation: true, // 透視衰減});return new THREE.Points(geometry, material);
}onMounted(() => {const stars = createStars();scene.add(stars);
});
</script>
2.2 動態雨雪
<script setup>
import { ref, onMounted } from 'vue';
import * as THREE from 'three';const rainGeometry = ref(null);
const rainMaterial = ref(null);
const rainSystem = ref(null);// 初始化雨滴
onMounted(() => {const rainCount = 5000;rainGeometry.value = new THREE.BufferGeometry();// 初始位置(頂部隨機分布)const positions = new Float32Array(rainCount * 3);for (let i = 0; i < rainCount * 3; i += 3) {positions[i] = Math.random() * 100 - 50; // xpositions[i+1] = Math.random() * 50 + 50; // ypositions[i+2] = Math.random() * 100 - 50; // z}rainGeometry.value.setAttribute('position', new THREE.BufferAttribute(positions, 3));// 創建雨滴材質rainMaterial.value = new THREE.PointsMaterial({color: 0xaaaaaa,size: 0.1,transparent: true,opacity: 0.8,});rainSystem.value = new THREE.Points(rainGeometry.value, rainMaterial.value);scene.add(rainSystem.value);
});// 更新動畫
function animateRain() {const positions = rainGeometry.value.attributes.position.array;for (let i = 1; i < positions.length; i += 3) {positions[i] -= 0.5; // Y軸下落// 重置位置(到達地面后回到頂部)if (positions[i] < -50) {positions[i] = Math.random() * 50 + 50;positions[i-2] = Math.random() * 100 - 50; // 重置Xpositions[i+1] = Math.random() * 100 - 50; // 重置Z}}// 標記更新rainGeometry.value.attributes.position.needsUpdate = true;
}
</script>
3. 高級粒子技術
3.1 粒子紋理
// 加載粒子貼圖
const textureLoader = new THREE.TextureLoader();
const particleTexture = textureLoader.load('textures/particle.png');const material = new THREE.PointsMaterial({map: particleTexture,alphaTest: 0.5, // 透明度閾值blending: THREE.AdditiveBlending, // 疊加混合depthWrite: false, // 禁用深度寫入
});// 圓形粒子
const discTexture = new THREE.CanvasTexture(createDiscCanvas(64));
function createDiscCanvas(size) {const canvas = document.createElement('canvas');canvas.width = canvas.height = size;const ctx = canvas.getContext('2d');const center = size / 2;const gradient = ctx.createRadialGradient(center, center, 0,center, center, center);gradient.addColorStop(0, 'rgba(255,255,255,1)');gradient.addColorStop(1, 'rgba(255,255,255,0)');ctx.fillStyle = gradient;ctx.beginPath();ctx.arc(center, center, center, 0, Math.PI * 2);ctx.fill();return canvas;
}
3.2 粒子物理
// 添加重力
const gravity = -0.01;
const velocities = new Float32Array(particleCount * 3);function initPhysics() {for (let i = 0; i < particleCount; i++) {velocities[i * 3] = (Math.random() - 0.5) * 0.1; // vxvelocities[i * 3 + 1] = Math.random() * 0.5 + 0.1; // vyvelocities[i * 3 + 2] = (Math.random() - 0.5) * 0.1; // vz}
}function updatePhysics() {const positions = geometry.attributes.position.array;for (let i = 0; i < particleCount; i++) {const idx = i * 3;// 更新速度velocities[idx + 1] += gravity;// 更新位置positions[idx] += velocities[idx];positions[idx + 1] += velocities[idx + 1];positions[idx + 2] += velocities[idx + 2];// 地面碰撞檢測if (positions[idx + 1] < 0) {positions[idx + 1] = 0;velocities[idx + 1] = -velocities[idx + 1] * 0.8; // 反彈}}geometry.attributes.position.needsUpdate = true;
}
3.3 粒子交互
// 鼠標交互影響粒子
const raycaster = new THREE.Raycaster();
const mouse = new THREE.Vector2();function onMouseMove(event) {// 計算鼠標位置mouse.x = (event.clientX / window.innerWidth) * 2 - 1;mouse.y = -(event.clientY / window.innerHeight) * 2 + 1;// 更新射線raycaster.setFromCamera(mouse, camera);// 計算鼠標在空間中的位置const plane = new THREE.Plane(new THREE.Vector3(0, 1, 0), 0);const intersectPoint = new THREE.Vector3();raycaster.ray.intersectPlane(plane, intersectPoint);// 影響粒子const positions = geometry.attributes.position.array;const center = new THREE.Vector3(intersectPoint.x,intersectPoint.y,intersectPoint.z);for (let i = 0; i < particleCount; i++) {const idx = i * 3;const particlePos = new THREE.Vector3(positions[idx],positions[idx+1],positions[idx+2]);const distance = particlePos.distanceTo(center);if (distance < 5) {const direction = particlePos.clone().sub(center).normalize();const force = (5 - distance) * 0.01;positions[idx] += direction.x * force;positions[idx+1] += direction.y * force;positions[idx+2] += direction.z * force;}}geometry.attributes.position.needsUpdate = true;
}
4. GPU加速粒子
4.1 ShaderMaterial定制
<script setup>
import { ref, onMounted } from 'vue';
import * as THREE from 'three';// 頂點著色器
const vertexShader = `attribute float size;attribute vec3 customColor;varying vec3 vColor;void main() {vColor = customColor;vec4 mvPosition = modelViewMatrix * vec4(position, 1.0);gl_PointSize = size * (300.0 / -mvPosition.z); // 透視縮放gl_Position = projectionMatrix * mvPosition;}
`;// 片元著色器
const fragmentShader = `varying vec3 vColor;uniform sampler2D pointTexture;void main() {gl_FragColor = vec4(vColor, 1.0);gl_FragColor = gl_FragColor * texture2D(pointTexture, gl_PointCoord);// 圓形粒子if (length(gl_PointCoord - vec2(0.5)) > 0.5) {discard;}}
`;// 創建自定義粒子材質
const particleMaterial = ref(null);onMounted(() => {particleMaterial.value = new THREE.ShaderMaterial({uniforms: {pointTexture: { value: new THREE.TextureLoader().load('particle.png') }},vertexShader,fragmentShader,blending: THREE.AdditiveBlending,depthTest: false,transparent: true});
});
</script>
4.2 計算著色器(WebGPU)
// 使用WebGPU計算著色器
import { GPUComputationRenderer } from 'three/addons/misc/GPUComputationRenderer.js';const gpuCompute = new GPUComputationRenderer(1024, 1024, renderer);// 創建位置紋理
const positionTexture = gpuCompute.createTexture();
initPositionTexture(positionTexture);// 創建速度紋理
const velocityTexture = gpuCompute.createTexture();
initVelocityTexture(velocityTexture);// 創建計算著色器
const positionShader = `uniform float time;uniform sampler2D velocityTexture;void main() {vec2 uv = gl_FragCoord.xy / resolution.xy;vec4 velocity = texture2D(velocityTexture, uv);// 更新位置vec4 position = texture2D(positionTexture, uv);position.xyz += velocity.xyz * 0.05;// 邊界約束if (position.x > 50.0) position.x = -50.0;// 其他邊界...gl_FragColor = position;}
`;const positionVariable = gpuCompute.addVariable('positionTexture', positionShader, positionTexture
);// 類似創建速度著色器...// 初始化計算
gpuCompute.setVariableDependencies(positionVariable, [positionVariable, velocityVariable]);
gpuCompute.init();
4.3 Instanced Particles
// 使用實例化粒子
const particleGeometry = new THREE.InstancedBufferGeometry();
particleGeometry.instanceCount = 100000;// 基礎幾何(一個點)
particleGeometry.setAttribute('position',new THREE.BufferAttribute(new Float32Array([0, 0, 0]), 3)
);// 實例化屬性
const offsets = new Float32Array(100000 * 3);
const colors = new Float32Array(100000 * 3);
const sizes = new Float32Array(100000);// 填充數據
for (let i = 0; i < 100000; i++) {offsets[i * 3] = Math.random() * 100 - 50;offsets[i * 3 + 1] = Math.random() * 100 - 50;offsets[i * 3 + 2] = Math.random() * 100 - 50;colors[i * 3] = Math.random();colors[i * 3 + 1] = Math.random();colors[i * 3 + 2] = Math.random();sizes[i] = Math.random() * 2 + 0.5;
}// 設置屬性
particleGeometry.setAttribute('offset',new THREE.InstancedBufferAttribute(offsets, 3)
);
particleGeometry.setAttribute('color',new THREE.InstancedBufferAttribute(colors, 3)
);
particleGeometry.setAttribute('size',new THREE.InstancedBufferAttribute(sizes, 1)
);// 創建材質
const material = new THREE.ShaderMaterial({vertexShader: `...`,fragmentShader: `...`,uniforms: { /* ... */ }
});const particleSystem = new THREE.Points(particleGeometry, material);
scene.add(particleSystem);
5. Vue3粒子編輯器
5.1 項目結構
src/├── components/│ ├── ParticleEditor.vue // 主編輯器│ ├── ParticlePreview.vue // 3D預覽│ ├── EffectLibrary.vue // 效果庫│ └── ParticleParams.vue // 參數控制└── App.vue
5.2 主編輯器
<!-- ParticleEditor.vue -->
<template><div class="particle-editor"><div class="sidebar"><EffectLibrary @select-effect="setActiveEffect" /><ParticleParams :effect="activeEffect" @update="updateEffect" /></div><div class="preview-container"><ParticlePreview ref="previewRef" :effect-config="activeEffect" /></div></div>
</template><script setup>
import { ref, reactive } from 'vue';
import { particleEffects } from './particle-presets';const activeEffect = ref(null);
const previewRef = ref(null);// 設置活動效果
function setActiveEffect(effect) {activeEffect.value = { ...effect };previewRef.value.applyEffect(activeEffect.value);
}// 更新效果
function updateEffect(newParams) {Object.assign(activeEffect.value, newParams);previewRef.value.updateEffect(activeEffect.value);
}
</script>
5.3 粒子預覽組件
<!-- ParticlePreview.vue -->
<script setup>
import { ref, onMounted, watch } from 'vue';
import * as THREE from 'three';
import { OrbitControls } from 'three/addons/controls/OrbitControls.js';const props = defineProps(['effectConfig']);
const canvasRef = ref(null);// 場景初始化
const scene = new THREE.Scene();
scene.background = new THREE.Color(0x0a0a2a); // 深藍色背景
const camera = new THREE.PerspectiveCamera(75, 1, 0.1, 1000);
camera.position.z = 15;
const renderer = ref(null);
const controls = ref(null);
const particleSystem = ref(null);onMounted(() => {renderer.value = new THREE.WebGLRenderer({canvas: canvasRef.value,antialias: true});renderer.value.setSize(800, 600);controls.value = new OrbitControls(camera, renderer.value.domElement);// 添加基礎燈光const ambientLight = new THREE.AmbientLight(0xffffff, 0.3);scene.add(ambientLight);const directionalLight = new THREE.DirectionalLight(0xffffff, 0.7);directionalLight.position.set(5, 10, 7);scene.add(directionalLight);// 啟動動畫循環animate();
});// 應用效果配置
function applyEffect(config) {// 清除舊系統if (particleSystem.value) {scene.remove(particleSystem.value);particleSystem.value.geometry.dispose();particleSystem.value.material.dispose();}// 創建新系統particleSystem.value = createParticleSystem(config);scene.add(particleSystem.value);
}// 更新效果
function updateEffect(config) {if (!particleSystem.value) return;// 更新材質particleSystem.value.material.size = config.particleSize;particleSystem.value.material.color = new THREE.Color(config.color);// 更新幾何體if (config.particleCount !== currentCount) {applyEffect(config);}
}// 動畫循環
function animate() {requestAnimationFrame(animate);// 更新粒子if (particleSystem.value) {updateParticles(particleSystem.value, props.effectConfig);}controls.value.update();renderer.value.render(scene, camera);
}
</script>
5.4 效果預設庫
<!-- EffectLibrary.vue -->
<template><div class="effect-library"><div v-for="effect in effects" :key="effect.id"class="effect-card":class="{ active: effect.id === activeId }"@click="selectEffect(effect)"><div class="thumbnail" :style="{background: `radial-gradient(circle, ${effect.color} 0%, #000 100%)`}"></div><h4>{{ effect.name }}</h4></div></div>
</template><script setup>
import { ref } from 'vue';const effects = ref([{id: 'fire',name: '火焰效果',color: '#ff5722',particleCount: 5000,particleSize: 0.5,// 其他參數...},{id: 'snow',name: '飄雪效果',color: '#ffffff',particleCount: 10000,particleSize: 0.2,// 其他參數...},{id: 'magic',name: '魔法粒子',color: '#9c27b0',particleCount: 8000,particleSize: 0.3,// 其他參數...},{id: 'stars',name: '宇宙星空',color: '#4fc3f7',particleCount: 20000,particleSize: 0.7,// 其他參數...}
]);const activeId = ref(null);
const emit = defineEmits(['select-effect']);function selectEffect(effect) {activeId.value = effect.id;emit('select-effect', effect);
}
</script>
5.5 參數控制面板
<!-- ParticleParams.vue -->
<template><div class="particle-params" v-if="effect"><h3>{{ effect.name }} 參數</h3><div class="control-group"><label>粒子數量: {{ effect.particleCount }}</label><input type="range" v-model.number="localEffect.particleCount" min="100" max="100000" step="100"@input="updateParams"></div><div class="control-group"><label>粒子大小: {{ effect.particleSize.toFixed(2) }}</label><input type="range" v-model.number="localEffect.particleSize" min="0.01" max="2" step="0.01"@input="updateParams"></div><div class="control-group"><label>粒子顏色</label><input type="color" v-model="localEffect.color"@change="updateParams"></div><div class="control-group" v-if="effect.type === 'fire'"><label>火焰強度: {{ effect.intensity.toFixed(2) }}</label><input type="range" v-model.number="localEffect.intensity" min="0.1" max="5" step="0.1"@input="updateParams"></div><!-- 其他效果特定參數 --></div>
</template><script setup>
import { ref, watch } from 'vue';const props = defineProps(['effect']);
const emit = defineEmits(['update']);const localEffect = ref({ ...props.effect });// 監聽外部變化
watch(() => props.effect, (newVal) => {localEffect.value = { ...newVal };
});// 更新參數
function updateParams() {emit('update', { ...localEffect.value });
}
</script>
6. 百萬級粒子優化
6.1 性能優化策略
6.2 渲染優化技術
-
Frustum Culling:
// 自定義視錐剔除 const frustum = new THREE.Frustum(); const viewProjectionMatrix = new THREE.Matrix4();function updateCulling() {viewProjectionMatrix.multiplyMatrices(camera.projectionMatrix,camera.matrixWorldInverse);frustum.setFromProjectionMatrix(viewProjectionMatrix);particleSystem.visible = frustum.intersectsSphere(particleSystem.geometry.boundingSphere); }
-
Level of Detail:
// 根據距離調整細節 function updateLOD() {const distance = camera.position.distanceTo(particleSystem.position);if (distance > 100) {particleSystem.material.size = 0.1;particleSystem.geometry.setDrawRange(0, 1000); // 只渲染部分粒子} else if (distance > 50) {particleSystem.material.size = 0.3;particleSystem.geometry.setDrawRange(0, 5000);} else {particleSystem.material.size = 0.5;particleSystem.geometry.setDrawRange(0, 10000);} }
-
Batch Rendering:
// 合并粒子系統 const mergedGeometry = new THREE.BufferGeometry(); const particleSystems = [system1, system2, system3];particleSystems.forEach(system => {const geometry = system.geometry.clone();geometry.applyMatrix4(system.matrixWorld);mergedGeometry.merge(geometry); });const mergedParticles = new THREE.Points(mergedGeometry,baseMaterial );
6.3 內存優化
// 重用幾何體
const particlePool = [];
const POOL_SIZE = 10;function createParticlePool() {for (let i = 0; i < POOL_SIZE; i++) {const geometry = new THREE.BufferGeometry();const material = new THREE.PointsMaterial();const system = new THREE.Points(geometry, material);system.visible = false;scene.add(system);particlePool.push(system);}
}function getParticleSystem() {for (const system of particlePool) {if (!system.visible) {system.visible = true;return system;}}// 如果池已滿,創建新系統return createNewSystem();
}
7. 粒子效果案例
7.1 火焰效果
function createFireEffect() {const count = 5000;const geometry = new THREE.BufferGeometry();// 位置、顏色、大小屬性const positions = new Float32Array(count * 3);const colors = new Float32Array(count * 3);const sizes = new Float32Array(count);for (let i = 0; i < count; i++) {const i3 = i * 3;// 初始位置(火源中心)positions[i3] = (Math.random() - 0.5) * 2;positions[i3+1] = 0;positions[i3+2] = (Math.random() - 0.5) * 2;// 顏色(從黃到紅)const hue = 0.1 + Math.random() * 0.1;colors[i3] = 1.0; // Rcolors[i3+1] = hue; // Gcolors[i3+2] = 0.0; // B// 初始大小sizes[i] = Math.random() * 0.5 + 0.1;}geometry.setAttribute('position', new THREE.BufferAttribute(positions, 3));geometry.setAttribute('color', new THREE.BufferAttribute(colors, 3));geometry.setAttribute('size', new THREE.BufferAttribute(sizes, 1));// 材質const material = new THREE.PointsMaterial({vertexColors: true,size: 0.5,blending: THREE.AdditiveBlending,depthWrite: false,transparent: true});return new THREE.Points(geometry, material);
}function updateFire(particles) {const positions = particles.geometry.attributes.position.array;const colors = particles.geometry.attributes.color.array;const sizes = particles.geometry.attributes.size.array;for (let i = 0; i < positions.length / 3; i++) {const i3 = i * 3;// 粒子上升positions[i3+1] += Math.random() * 0.1;// 隨機左右擺動positions[i3] += (Math.random() - 0.5) * 0.05;positions[i3+2] += (Math.random() - 0.5) * 0.05;// 顏色變暗(模擬冷卻)colors[i3+1] = Math.max(0, colors[i3+1] - 0.005);// 粒子縮小sizes[i] = Math.max(0.05, sizes[i] - 0.001);// 重置粒子if (positions[i3+1] > 10 || sizes[i] <= 0.05) {positions[i3+1] = 0;positions[i3] = (Math.random() - 0.5) * 2;positions[i3+2] = (Math.random() - 0.5) * 2;colors[i3+1] = 0.1 + Math.random() * 0.1;sizes[i] = Math.random() * 0.5 + 0.1;}}particles.geometry.attributes.position.needsUpdate = true;particles.geometry.attributes.color.needsUpdate = true;particles.geometry.attributes.size.needsUpdate = true;
}
7.2 數據可視化
function createDataVisualization(points) {const geometry = new THREE.BufferGeometry();// 位置和顏色const positions = new Float32Array(points.length * 3);const colors = new Float32Array(points.length * 3);points.forEach((point, i) => {const i3 = i * 3;// 位置positions[i3] = point.x;positions[i3+1] = point.y;positions[i3+2] = point.z;// 顏色(基于值)const color = new THREE.Color();color.setHSL(0.6 * point.value, 1.0, 0.5);colors[i3] = color.r;colors[i3+1] = color.g;colors[i3+2] = color.b;});geometry.setAttribute('position', new THREE.BufferAttribute(positions, 3));geometry.setAttribute('color', new THREE.BufferAttribute(colors, 3));// 材質const material = new THREE.PointsMaterial({vertexColors: true,size: 2.0,sizeAttenuation: false});return new THREE.Points(geometry, material);
}
8. 常見問題解答
Q1:粒子顯示為方塊而不是圓形?
// 解決方案1:使用圓形紋理
material.map = createCircleTexture();// 解決方案2:在著色器中處理
void main() {float distance = length(gl_PointCoord - vec2(0.5));if (distance > 0.5) discard;// ...
}// 解決方案3:開啟抗鋸齒
renderer = new THREE.WebGLRenderer({ antialias: true });
Q2:移動端粒子性能差怎么辦?
- 減少粒子數量(<5000)
- 禁用大小衰減
sizeAttenuation: false
- 使用簡單著色器
- 降低更新頻率(每秒30幀)
Q3:如何實現粒子拖尾效果?
// 使用GPU粒子實現拖尾
const trailShader = `uniform sampler2D positionTexture;uniform sampler2D prevPositionTexture;void main() {vec2 uv = gl_FragCoord.xy / resolution.xy;vec4 position = texture2D(positionTexture, uv);vec4 prevPosition = texture2D(prevPositionTexture, uv);// 混合當前和之前位置vec4 newPosition = mix(position, prevPosition, 0.8);gl_FragColor = newPosition;}
`;// 渲染時繪制多條軌跡
for (let i = 0; i < TRAIL_LENGTH; i++) {const trailMaterial = new THREE.PointsMaterial({color: baseColor,size: baseSize * (1 - i/TRAIL_LENGTH),opacity: 1 - i/TRAIL_LENGTH,transparent: true});const trail = new THREE.Points(geometry, trailMaterial);scene.add(trail);
}
9. 總結
通過本文,你已掌握:
- 粒子系統核心組件(Points/PointsMaterial)
- 基礎粒子效果實現(星空/雨雪)
- 高級粒子技術(紋理/物理/交互)
- GPU加速與計算著色器
- Vue3粒子編輯器開發
- 百萬級粒子優化策略
- 實戰效果案例(火焰/數據可視化)
核心價值:Three.js粒子系統通過GPU加速渲染,結合著色器編程,實現了百萬級粒子的實時交互,為Web應用帶來影院級視覺效果。
下一篇預告
第十三篇:后期處理:效果增強
你將學習:
- 后期處理管線原理
- 內置效果鏈(Bloom/SSAO/Glitch)
- 自定義ShaderPass開發
- 性能優化:多采樣與降級
- 高級特效:景深、運動模糊
- Vue3實現后期處理編輯器