我将.3DS模型导入Blender 2.72b，然后使用Three.js导入/导出插件导出它们。这些模型具有多个几何“岛”（连接的面和顶点的独立组），每个都有自己的材料。我希望能够将每种材料与其相应的岛配对，而无需创建单独的THREE.Geometry对象。经过一番挖掘后，我发现this question建议使用THREE.MeshFaceMaterial为一个对象实现多种材质。唯一的问题是该示例中的几何是一个简单的立方体，而我的模型有数百个面分布在2-5个岛上。
Three.js是否具有识别网格中几何体“孤岛”的功能？
答案 0 :(得分：2)
没有。 three.js没有用于识别网格中几何体“孤岛”的功能。
使用MeshFaceMaterial时，WebGLRenderer无论如何都会将几何体分成几个块 - 每个材质都有一个块。这样做是因为WebGL支持每个几何体一个着色器。
我不会合并所有几何图形，然后使用MeshFaceMaterial，只是让渲染器将单个几何图形分开。
如果愿意，您可以合并共享单个材质的几何图形。
three.js r.69
答案 1 :(得分：0)
我尝试了一个函数，但仍然不准确，它产生的几何图形比非连接几何图形多：
如果有人可以看看它，那就太好了。
function groupGeometryIntoNonConnectedGeometries(geometry) {
const material = new THREE.MeshBasicMaterial({
side: THREE.DoubleSide,
vertexColors: THREE.VertexColors
});
let geometryArray = [];
const indexArray = geometry.index.array;
const positionArray = geometry.attributes.position.array;
const positionCount = geometry.attributes.position.count;
const color = new THREE.Vector3(geometry.attributes.color.array[0], geometry.attributes.color.array[1], geometry.attributes.color.array[2]);
const totalTriangles = indexArray.length / 3;
let geometryCount = 0;
let indexValueAlreadyVisited = new Uint8Array(indexArray.length);
let structure = [];
/*
* indexValue: {
* child: [ [indexval0, indexval1], [] ],
* parent: null
* }
*/
// Initialize Structure:
for (var vextexIdx=0; vextexIdx<positionCount; vextexIdx++) {
structure[vextexIdx] = {
child: [],
parent: null
}
}
for (idx=0; idx<totalTriangles; idx++) {
const geoIndex1 = indexArray[idx*3];
const geoIndex2 = indexArray[idx*3+1];
const geoIndex3 = indexArray[idx*3+2];
const triangleIndexVertexArray = [ geoIndex1, geoIndex2, geoIndex3 ].sort(function(a, b) {
return a - b;
});
structure[ triangleIndexVertexArray[0] ].child.push(triangleIndexVertexArray[1], triangleIndexVertexArray[2]);
structure[ triangleIndexVertexArray[1] ].parent = triangleIndexVertexArray[0];
structure[ triangleIndexVertexArray[2] ].parent = triangleIndexVertexArray[0];
}
let count = 0;
let currentCount = 0;
let geometryStructureArray = [];
for (let strIdx=0; strIdx<structure.length; strIdx++) {
if (structure[strIdx].parent == null) {
currentCount = count;
geometryStructureArray[currentCount] = {
name: "G_" + currentCount,
indexMap: {},
currentIndex: 0,
indexArray: [],
positionArray: [],
colorArray: []
};
count += 1;
}
if (structure[strIdx].child.length > 0) {
const childLen = structure[strIdx].child.length / 2;
for (let childIdx=0; childIdx<childLen; childIdx++) {
const vertexIndex0 = strIdx;
const vertexIndex1 = structure[strIdx].child[childIdx*2];
const vertexIndex2 = structure[strIdx].child[childIdx*2+1];
const v0 = new THREE.Vector3( positionArray[strIdx*3], positionArray[strIdx*3+1], positionArray[strIdx*3+2] );
const v1 = new THREE.Vector3( positionArray[vertexIndex1*3], positionArray[vertexIndex1*3+1], positionArray[vertexIndex1*3+2] );
const v2 = new THREE.Vector3( positionArray[vertexIndex2*3], positionArray[vertexIndex2*3+1], positionArray[vertexIndex2*3+2] );
// check vertex0
if (geometryStructureArray[currentCount].indexMap[vertexIndex0] == undefined) {
geometryStructureArray[currentCount].indexMap[vertexIndex0] = geometryStructureArray[currentCount].currentIndex;
geometryStructureArray[currentCount].indexArray.push(geometryStructureArray[currentCount].currentIndex);
geometryStructureArray[currentCount].positionArray.push(v0.x, v0.y, v0.z);
geometryStructureArray[currentCount].colorArray.push(color.x, color.y, color.z);
geometryStructureArray[currentCount].currentIndex += 1;
} else {
geometryStructureArray[currentCount].indexArray.push(geometryStructureArray[currentCount].indexMap[vertexIndex0]);
}
// check vertex1
if (geometryStructureArray[currentCount].indexMap[vertexIndex1] == undefined) {
geometryStructureArray[currentCount].indexMap[vertexIndex1] = geometryStructureArray[currentCount].currentIndex;
geometryStructureArray[currentCount].indexArray.push(geometryStructureArray[currentCount].currentIndex);
geometryStructureArray[currentCount].positionArray.push(v1.x, v1.y, v1.z);
geometryStructureArray[currentCount].colorArray.push(color.x, color.y, color.z);
geometryStructureArray[currentCount].currentIndex += 1;
} else {
geometryStructureArray[currentCount].indexArray.push(geometryStructureArray[currentCount].indexMap[vertexIndex1]);
}
// check vertex1
if (geometryStructureArray[currentCount].indexMap[vertexIndex2] == undefined) {
geometryStructureArray[currentCount].indexMap[vertexIndex2] = geometryStructureArray[currentCount].currentIndex;
geometryStructureArray[currentCount].indexArray.push(geometryStructureArray[currentCount].currentIndex);
geometryStructureArray[currentCount].positionArray.push(v2.x, v2.y, v2.z);
geometryStructureArray[currentCount].colorArray.push(color.x, color.y, color.z);
geometryStructureArray[currentCount].currentIndex += 1;
} else {
geometryStructureArray[currentCount].indexArray.push(geometryStructureArray[currentCount].indexMap[vertexIndex2]);
}
}
}
}
// Convert to geometryArray:
const geometryStructureArrayLen = geometryStructureArray.length;
const object3d = new THREE.Object3D();
for (let geoIdx=0; geoIdx<geometryStructureArrayLen; geoIdx++) {
const geo = new THREE.BufferGeometry();
geo.name = "G_" + geoIdx;
const geoPositions = new Float32Array(geometryStructureArray[geoIdx].positionArray);
const geoColors = new Float32Array(geometryStructureArray[geoIdx].colorArray);
const geoIndices = new Uint32Array(geometryStructureArray[geoIdx].indexArray);
//console.log(geoIdx, "geoPositions: ", geoPositions);
//console.log(geoIdx, "geoColors: ", geoColors);
//console.log(geoIdx, "geoIndices: ", geoIndices);
geo.index = new THREE.BufferAttribute(geoIndices, 1, false);
geo.attributes.position = new THREE.BufferAttribute(geoPositions, 3, false);
geo.attributes.color = new THREE.BufferAttribute(geoColors, 3, true);
geo.computeBoundingSphere();
geo.computeBoundingBox();
const mesh = new THREE.Mesh(geo, material);
mesh.name = "M_" + geoIdx;
object3d.add(mesh);
}
//return [structure, geometryStructureArray, object3d, count];
return object3d;
}
最好的问候