基于我最近发布的上一个问题： How to create lines between nearby particles in ThreeJS?
我能够创建连接附近粒子的单独线条。然而，由于粒子系统的逻辑，线被绘制两次。这是因为原始2D粒子系统的工作原理： https://awingit.github.io/particles/
这也画了两次。对于连接线的每对粒子，绘制线。
我认为这不是性能的理想选择。我怎么只为每个加入点画一次线？
P.S。这正是我想要实现的效果，但无法理解代码： http://freelance-html-developer.com/clock/
我想了解基本逻辑。
更新：
我已根据我的进度创建了jsfiddle。
var canvas, canvasDom, ctx, scene, renderer, camera, controls, geocoder, deviceOrientation = false;
var width = 800,
height = 600;
var particleCount = 20;
var pMaterial = new THREE.PointsMaterial({
color: 0x000000,
size: 0.5,
blending: THREE.AdditiveBlending,
//depthTest: false,
//transparent: true
});
var particles = new THREE.Geometry;
var particleSystem;
var line;
var lines = {};
var lineGroup = new THREE.Group();
var lineMaterial = new THREE.LineBasicMaterial({
color: 0x000000,
linewidth: 1
});
var clock = new THREE.Clock();
var maxDistance = 15;
function init() {
canvasDom = document.getElementById('canvas');
setupStage();
setupRenderer();
setupCamera();
setupControls();
setupLights();
clock.start();
window.addEventListener('resize', onWindowResized, false);
onWindowResized(null);
createParticles();
scene.add(lineGroup);
animate();
}
function setupStage() {
scene = new THREE.Scene();
}
function setupRenderer() {
renderer = new THREE.WebGLRenderer({
canvas: canvasDom,
logarithmicDepthBuffer: true
});
renderer.setSize(width, height);
renderer.setClearColor(0xfff6e6);
}
function setupCamera() {
camera = new THREE.PerspectiveCamera(70, width / height, 1, 10000);
camera.position.set(0, 0, -60);
}
function setupControls() {
if (deviceOrientation) {
controls = new THREE.DeviceOrientationControls(camera);
controls.connect();
} else {
controls = new THREE.OrbitControls(camera, renderer.domElement);
controls.target = new THREE.Vector3(0, 0, 0);
}
}
function setupLights() {
var light1 = new THREE.AmbientLight(0xffffff, 0.5); // soft white light
var light2 = new THREE.PointLight(0xffffff, 1, 0);
light2.position.set(100, 200, 100);
scene.add(light1);
scene.add(light2);
}
function animate() {
requestAnimationFrame(animate);
controls.update();
animateParticles();
updateLines();
render();
}
function render() {
renderer.render(scene, camera);
}
function onWindowResized(event) {
width = window.innerWidth;
height = window.innerHeight;
camera.aspect = width / height;
camera.updateProjectionMatrix();
renderer.setSize(width, height);
}
function createParticles() {
for (var i = 0; i < particleCount; i++) {
var pX = Math.random() * 50 - 25,
pY = Math.random() * 50 - 25,
pZ = Math.random() * 50 - 25,
particle = new THREE.Vector3(pX, pY, pZ);
particle.diff = Math.random() + 0.2;
particle.default = new THREE.Vector3(pX, pY, pZ);
particle.offset = new THREE.Vector3(0, 0, 0);
particle.velocity = {};
particle.velocity.y = particle.diff * 0.5;
particle.nodes = [];
particles.vertices.push(particle);
}
particleSystem = new THREE.Points(particles, pMaterial);
particleSystem.position.y = 0;
scene.add(particleSystem);
}
function animateParticles() {
var pCount = particleCount;
while (pCount--) {
var particle = particles.vertices[pCount];
var move = Math.sin(clock.getElapsedTime() * (1 * particle.diff)) / 4;
particle.offset.y += move * particle.velocity.y;
particle.y = particle.default.y + particle.offset.y;
detectCloseByPoints(particle);
}
particles.verticesNeedUpdate = true;
particleSystem.rotation.y += 0.01;
lineGroup.rotation.y += 0.01;
}
function updateLines() {
for (var _lineKey in lines) {
if (!lines.hasOwnProperty(_lineKey)) {
continue;
}
lines[_lineKey].geometry.verticesNeedUpdate = true;
}
}
function detectCloseByPoints(p) {
var _pCount = particleCount;
while (_pCount--) {
var _particle = particles.vertices[_pCount];
if (p !== _particle) {
var _distance = p.distanceTo(_particle);
var _connection = checkConnection(p, _particle);
if (_distance < maxDistance) {
if (!_connection) {
createLine(p, _particle);
}
} else if (_connection) {
removeLine(_connection);
}
}
}
}
function checkConnection(p1, p2) {
var _childNode, _parentNode;
_childNode = p1.nodes[particles.vertices.indexOf(p2)] || p2.nodes[particles.vertices.indexOf(p1)];
if (_childNode && _childNode !== undefined) {
_parentNode = (_childNode == p1) ? p2 : p1;
}
if (_parentNode && _parentNode !== undefined) {
return {
parent: _parentNode,
child: _childNode,
lineId: particles.vertices.indexOf(_parentNode) + '-' + particles.vertices.indexOf(_childNode)
};
} else {
return false;
}
}
function removeLine(_connection) {
// Could animate line out
var childIndex = particles.vertices.indexOf(_connection.child);
_connection.parent.nodes.splice(childIndex, 1);
deleteLine(_connection.lineId);
}
function deleteLine(_id) {
lineGroup.remove(lines[_id]);
delete lines[_id];
}
function addLine(points) {
var points = points || [new THREE.Vector3(Math.random() * 10, Math.random() * 10, Math.random() * 10), new THREE.Vector3(0, 0, 0)];
var _lineId = particles.vertices.indexOf(points[0]) + '-' + particles.vertices.indexOf(points[1]);
var lineGeom = new THREE.Geometry();
if (!lines[_lineId]) {
lineGeom.dynamic = true;
lineGeom.vertices.push(points[0]);
lineGeom.vertices.push(points[1]);
var curLine = new THREE.Line(lineGeom, lineMaterial);
curLine.touched = false;
lines[_lineId] = curLine;
lineGroup.add(curLine);
return curLine;
} else {
return false;
}
}
function createLine(p1, p2) {
p1.nodes[particles.vertices.indexOf(p2)] = p2;
addLine([p1, p2]);
}
$(document).ready(function() {
init();
});
我非常接近，但我不确定它是否已经过优化。似乎有闪烁的线条，有时一条线只是卡在原地。
所以这是我的想法。我点击了我所要做的就是让行的Vector3点等于相关的粒子Vector3点。我只需要更新每一行geometry.verticesNeedUpdate = true;
另外，我如何管理这些行是我使用2点的索引创建一个唯一的ID，例如lines ['8-2'] = line
答案 0 :(得分：1)
您实际尝试解决的问题是，在循环查看积分列表时，您的成功匹配次数会翻倍。
示例：
考虑点列表[A, B, C, D]。您的循环测试每个点与所有其他点。对于此示例，A和C是唯一足够接近附近的点。
在第一次迭代期间，A与所有人相比，您发现附近有A和C，因此您需要添加一行。但是当您为C进行迭代时，您还会发现A就在附近。这会导致您要避免的第二行。
修复它：
解决方案很简单：不要重新访问已检查过的节点。这是有效的，因为distance from A to C的答案与distance from C to A没有区别。
执行此操作的最佳方法是调整检查循环的索引：
// (Note: This is example code, and won't "just work.")
for(var check = 0, checkLength = nodes.length; check < checkLength; ++check){
for(var against = check + 1, against < checkLength; ++against){
if(nodes[check].distanceTo(nodes[against]) < delta){
buildThatLine(nodes[check], nodes[against]);
}
}
}
在内部循环中，索引设置为：
这是通过将内部索引初始化为外部索引+ 1来完成的。
<强>警告：
这个特殊的逻辑假定您丢弃每帧的所有行。它不是实现这种效果的最有效方式，但我会让它更有效地为你锻炼。