我正在通过 dat.gui 上传一个具有 8 个顶点和 6 个面(顶点索引)的 3D *.obj(例如立方体)。虽然我可以成功地将点移动到顶点,但我无法将它们均匀分布在模型的面上。
这是我到目前为止的流程:
(1)加载对象文件
示例 *.obj 非常简单:
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) trim 其顶点和面
我使用正则表达式模式来 trim 顶点和面,然后将它们推送到我的几何图形。
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。这工作得很好。
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) 在脸上分布粒子
我现在有一个切换开关,我想在立方体的面上均匀地散布相同的粒子。我尝试使用 GeometryUtils.randomPointsInGeometry 来做到这一点
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,而不是均匀地分布在面部区域上。有什么线索吗?
-- 这些是我得到的面孔 (THREE.Face3):
{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]…}
他们计算的面积始终为零。
类似问题: THREE.js - position particles evenly on objects faces rather than verticies
最佳答案
好的 - 我花了一段时间,但我解决了它。
我按照 G.Profenza 的建议尝试了 OBJLoader 方法。
基本上加载对象,获取其网格,使用GeometryUtils.randomPointsinBufferGeometry,然后将粒子移动到您获得的向量3:
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 );
}
关于javascript - 在 Threejs 中导入 *.obj 的面上移动粒子,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/36305961/