Threejs中导入的*.obj表面上的移动粒子 [英] moving particles on face of imported *.obj in threejs

问题描述

我正在通过 dat.gui 上传一个 3D *.obj(例如一个立方体)，具有 8 个顶点和 6 个面(顶点索引).虽然我可以成功地将我的点移动到顶点，但我无法将它们均匀地分布在模型的面上.

I'm uploading via dat.gui a 3D *.obj (e.g. a cube) with 8 vertices and 6 faces (vertex indices). Although I can successfully move my points to the vertices, I cannot evenly distribute them on the faces of the model.

这是我目前的流程:

(1) 加载对象文件

示例 *.obj 非常简单:

The example *.obj is quite simple:

v 5.526871 -3.827843 1.523720
v 5.526871 -1.827843 1.523720
v 5.526871 -3.827843 -0.476280
v 5.526871 -1.827843 -0.476280
v 7.526871 -3.827843 1.523720
v 7.526871 -1.827843 1.523720
v 7.526871 -3.827843 -0.476280
v 7.526871 -1.827843 -0.476280
s off
f 2 4 3 1
f 4 8 7 3
f 8 6 5 7
f 6 2 1 5
f 1 3 7 5
f 6 8 4 2

(2) 修剪它的顶点 &面孔

我正在使用 RegEx 模式修剪顶点和面，然后将它们推送到我的几何体.

I'm using RegEx patterns to trim the vertices and faces and then push them to my geometry.

var faces_pattern1 = /f( +[d]+)( [d]+)( [d]+)( [d]+)?/g; // f vertex vertex vertex ...
if ( (result = faces_pattern1.exec(line) ) !== null ) {
   faces_pattern1.exec(line); 
   if ( result[ 4 ] === undefined ) {
        faces1.push( [
            parseInt( result[ 1 ] ) - 1,
            parseInt( result[ 2 ] ) - 1,
            parseInt( result[ 3 ] ) - 1
        ] );
    } else {
        faces1.push( [
            parseInt( result[ 1 ] ) - 1,
            parseInt( result[ 2 ] ) - 1,
            parseInt( result[ 3 ] ) - 1,
            parseInt( result[ 4 ] ) - 1
         ] );
    }
}
// push faces to geometry
for (var i = 0; i < faces1.length; i++) {
    this.renderer.geometry.faces.push( new THREE.Face3( faces1[i][0], faces1[i][1], faces1[i][2], faces1[i][3] ) );
}

(3) 在顶点上移动粒子

我有许多粒子，我将它们定位到顶点.这工作正常.

I have a number of particles, which i position to the vertices. This works fine.

var lg = allParticle.length;
for( var i = 0; i < lg; i++ ){
    var p = allParticle[i];
    p.diffX = ( vertices[h][0] * scale - p.x );
    p.diffY = ( -vertices[h][1] * scale - p.y );
    p.diffZ = ( -vertices[h][2] * scale - p.z );
    h += 1;
    if( h > nbVertices - 1 ) h = 0;
}

(4) 在脸上散布粒子

我现在有一个开关，我想在立方体的表面上均匀地散布相同的粒子.我尝试使用 GeometryUtils.randomPointsInGeometry

I now have a toggle, where i want to evenly spread the same particles on the faces of the cube. I try to do this using GeometryUtils.randomPointsInGeometry

var randomPointPositions = THREE.GeometryUtils.randomPointsInGeometry( this.renderer.geometry, lg  );
this.renderer.geometry.computeBoundingBox();
for( var i = 0; i < randomPointPositions.length; i++ ){

  var p = allParticle[i];
  p.diffX = randomPointPositions[i].x * scale ;
  p.diffY = randomPointPositions[i].y * scale;
  p.diffZ = randomPointPositions[i].z * scale ;
}

这仅将点分布在 x 轴上，而不是均匀分布在面部区域上.有什么线索吗?

This distributes the points only on the x axis and not evenly on the area of the face. Any clues?

--这些是我得到的面孔 (THREE.Face3):

-- These are the faces (THREE.Face3) I'm getting:

{a: 1, b: 3, c: 2, normal: T…E.Vector3, vertexNormals: Array[0]…}
{a: 3, b: 7, c: 6, normal: T…E.Vector3, vertexNormals: Array[0]…}
{a: 7, b: 5, c: 4, normal: T…E.Vector3, vertexNormals: Array[0]…}
{a: 5, b: 1, c: 0, normal: T…E.Vector3, vertexNormals: Array[0]…}
{a: 0, b: 2, c: 6, normal: T…E.Vector3, vertexNormals: Array[0]…}
{a: 5, b: 7, c: 3, normal: T…E.Vector3, vertexNormals: Array[0]…}

他们计算的 _area 始终为零.

Their calculated _area is always zero.

类似问题:THREE.js - 将粒子均匀地放置在对象面上而不是顶点

推荐答案

好的 - 我花了一段时间，但我解决了.

ok - it took me a while, but I solved it.

我按照 G.Profenza 的建议尝试了 OBJLoader 方法.

I tried the OBJLoader Method as suggested by G.Profenza.

基本上加载对象，获取它的网格，使用 GeometryUtils.randomPointsinBufferGeometry 然后将粒子移动到你得到的 vector3:

Basically load the object, get its mesh, use the GeometryUtils.randomPointsinBufferGeometry and then move the particles to the vector3 you get:

OBJLoader: function() {
        var manager = new THREE.LoadingManager();
        manager.onProgress = function ( item, loaded, total ) {
            console.log( item, loaded, total );
        };

        var onProgress = function ( xhr ) {
            if ( xhr.lengthComputable ) {
                var percentComplete = xhr.loaded / xhr.total * 100;
                console.log( Math.round(percentComplete, 2) + '% downloaded' );
            }
        };

        var onError = function ( xhr ) {
            console.log ("ERROR", xhr);
        };

        var loader = new THREE.OBJLoader( manager );
        var allParticle = this.scene.getParticles();
        var lg = allParticle.length;
        var scale = this.renderer.scale;    
        loader.load( '/data/cube_02.obj', function ( object ) {
            object.traverse( function ( child ) {
            if ( child instanceof THREE.Mesh ) {
                console.log (" === CHILD === ");
                console.log (child.geometry);
                var randomPointPositions = THREE.GeometryUtils.randomPointsInBufferGeometry( child.geometry, lg  );


                console.log (randomPointPositions[0].x, randomPointPositions[0].y, randomPointPositions[0].z );


                for( var i = 0; i < randomPointPositions.length; i++ ){

                   var p = allParticle[i];
                   p.diffX = randomPointPositions[i].x * scale -p.x ;
                   p.diffY = randomPointPositions[i].y * scale -p.y;
                   p.diffZ = randomPointPositions[i].z * scale -p.z;
                }

            }

        } );


        //object.position.y = - 95;
        //this.renderer.sceneGL.add(object);

        }, onProgress, onError );



    }

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