THREE.js 向 Points 几何体动态添加点不渲染 [英] THREE.js dynamically add points to a Points geometry does not render

问题描述

我使用 Three.js r83.

I am using Three.js r83.

我正在尝试向几何体动态添加点，但场景永远不会更新.

I am trying to dynamically add points to a geometry, but the scene never gets updated.

这有效:

var tmaterial = new THREE.PointsMaterial({
    color: 0xff0000,
    size: 5,
    opacity: 1
});

var tgeometry = new THREE.Geometry();
var pointCloud = new THREE.Points(tgeometry, tmaterial);

for(var i = 0; i< 1000; i++) {
    x = (Math.random() * 200) - 100;
    y = (Math.random() * 200) - 100;
    z = (Math.random() * 200) - 100;
    tgeometry.vertices.push(new THREE.Vector3(x, y, z));
}
tgeometry.verticesNeedUpdate = true;
tgeometry.computeVertexNormals();

scene.add(pointCloud);

这不起作用:

var tmaterial = new THREE.PointsMaterial({
    color: 0xff0000,
    size: 5,
    opacity: 1
});

var tgeometry = new THREE.Geometry();
var pointCloud = new THREE.Points(tgeometry, tmaterial);
scene.add(pointCloud);

for(var i = 0; i< 1000; i++) {
    x = (Math.random() * 200) - 100;
    y = (Math.random() * 200) - 100;
    z = (Math.random() * 200) - 100;
    tgeometry.vertices.push(new THREE.Vector3(x, y, z));
}
tgeometry.verticesNeedUpdate = true;
tgeometry.elementsNeedUpdate = true;
tgeometry.computeVertexNormals();
renderer.render(scene, camera);

如您所见，唯一的区别是我在添加顶点之前添加了 scene.add(pointCloud);.

As you can see, the only difference is the fact that I add scene.add(pointCloud); before adding vertexes.

我想念什么?

您可以找到 fiddle 感谢@hectate

You can find a fiddle Thanks to @hectate

要明白我的意思，只需替换

To see what I means, just replace

init();设置点();动画()；

由

init();动画()；设置点();

推荐答案

我不确定为什么 THREE.Geometry 对象在初始渲染后不更新 Points，但我使用THREE.BufferGeometry 代替.

I am not sure why the THREE.Geometry object doesn't update Points after initial rendering, but I got it working with a THREE.BufferGeometry instead.

感谢 @Hectate 为我提供了一个工作小提琴，以及 @WestLangley 为我提供了提示，这里是工作小提琴

Thanks to @Hectate who got a working fiddle for me and @WestLangley who directed me to the hints, here is the working fiddle

BufferGeometry 具有固定数量的顶点，但您可以决定要渲染的顶点数量.诀窍是利用 geometry.attributes.position.needsUpdate = true; 和 geometry.setDrawRange( 0, nbPointsYouWantToDisplay );

BufferGeometry has a fixed number of Vertices, but you can decide how many of them you want to render. The trick is to make use of geometry.attributes.position.needsUpdate = true; and geometry.setDrawRange( 0, nbPointsYouWantToDisplay );

var MAX_POINTS = 1000000;
var geometry = new THREE.BufferGeometry();
var positions = new Float32Array( MAX_POINTS * 3 ); 
geometry.addAttribute( 'position', new THREE.BufferAttribute( positions, 3 ) );

然后您可以创建您的云点并将其添加到场景中:

Then you can create your cloudpoints and add it to the scene:

//material and scene defined in question
pointCloud = new THREE.Points(geometry, material);
scene.add(pointCloud);

现在我想每 10 毫秒添加和渲染 500 个新点.

Now I want to add and render 500 new points every 10 milliseconds.

var nbPoints = 500;
var INTERVAL_DURATION = 10;

我所要做的就是:

var interval = setInterval(function() {
  setPoints();
}, INTERVAL_DURATION)

function setPoints() {

  var positions = pointCloud.geometry.attributes.position.array;

  var x, y, z, index;

  var l  = currentPoints + nbPoints;
  if(l >= MAX_POINTS) {
    clearInterval(interval);
  }

  for ( var i = currentPoints; i < l; i ++ ) {
    x = ( Math.random() - 0.5 ) * 300;
    y = ( Math.random() - 0.5 ) * 300;
    z = ( Math.random() - 0.5 ) * 300;
    positions[ currentPointsIndex ++ ] = x;
    positions[ currentPointsIndex ++ ] = y;
    positions[ currentPointsIndex ++ ] = z;
  }
  currentPoints = l;
  pointCloud.geometry.attributes.position.needsUpdate = true;   
  pointCloud.geometry.setDrawRange( 0, currentPoints );  
  controls.update();
  renderer.render(scene, camera);

}

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