THREE.js无法对导入的OBJ文件应用渐变颜色

Question

我正在尝试从THREE.js加载和着色示例文件GIT叫做"WaltHead.obj">位置:

https://github.com/mrdoob/three.js/blob/dev/examples/models/obj/walt/WaltHead.obj

我可以将其加载到我的项目中，但是当我尝试使用已经100%为我工作的GLTF/GLB模型的代码用渐变颜色绘制它时-它不适用于这个"。obj"文件。

我做了一个小提琴，使生活更容易-但由于某种原因，模型没有加载到小提琴文件:

https://jsfiddle.net/gilomer88/tp2hkxne/27/

希望有人可以修复它，所以它加载?

无论哪种方式，就像我说的，我试图用渐变来给它上色——但它显示的是完全黑色的。代码在这里，也在这里:

const loader = new OBJLoader();
loader.load( "https://github.com/mrdoob/three.js/blob/dev/examples/models/obj/walt/WaltHead.obj", function ( theScene ) {
console.log("  =>'theScene' = ", theScene);
theScene.traverse(function(child) {
console.log("n==>Traversing the Scene now...");
if(child.isMesh) {
console.log("1. 'child' - FULL MESH INFO = ", child);

if(child.name) {
console.log(" 2. 'child.name' = ", child.name);
console.log(" 3. 'child.geometry' = ", child.geometry, "n");
if(child.name.startsWith("Mesh_Mesh_head")) {
// Calling a convenience method I made here - code below:
let theColors = makeSmoothGradientColorsForMesh(child, "orange", "white");
child.geometry.setAttribute("color", new THREE.Float32BufferAttribute(theColors, 3));     
child.material.vertexColors = true;
child.material.flatShading = false;
} 
} 
} 
}); 

scene.add(theScene);
theScene.position.set(0, 0, 0);
}) 

这是我的方便方法:

function makeSmoothGradientColorsForMesh(theMesh, c1, c2) {
console.log("nn===>In 'makeSmoothGradientColorsForMesh()'!n");
console.log(">Incoming meshObject: n", theMesh);
let meshGeometry = theMesh.geometry;
let meshMaterial = theMesh.material;
// Do the Geometry-Dance:
const positionAttribute = meshGeometry.getAttribute("position");
console.log(">positionAttribute = n", positionAttribute);
meshGeometry.computeVertexNormals();
// "BoundingBox" business:
meshGeometry.computeBoundingBox();
const aabb = meshGeometry.boundingBox;
console.log(">aabb = n", aabb);
const f = aabb.max.z - aabb.min.z;
const vertex = new THREE.Vector3();
// COLORS business:
let randomColor = new THREE.Color();
let colorsArray = [];
const c = new THREE.Color();                     
console.log("positionAttribute.count = ", positionAttribute.count);
for(let i = 0; i < positionAttribute.count; i++) {
vertex.fromBufferAttribute( positionAttribute, i );
c.lerpColors( c1, c2, ( vertex.z - aabb.min.z) / f );
colorsArray.push(c.r, c.g, c.b); 
}
console.log("nn-->Will be returning the following colors:n");
console.log(colorsArray);
return colorsArray;
}

由于某种原因，从我的makeSmoothGradientColorsForMesh()方法返回的颜色如下所示:

Array(145440) [ NaN, NaN, NaN, NaN, NaN, NaN, NaN, NaN, NaN, NaN, … ]

Answer 1

您的c.lerpColors()实现是错误的。您正在尝试将字符串传递到方法("orange", "white")，它将无法识别并返回NaN。

这个方法需要两个THREE.Color对象，所以你应该先初始化它们:

// We use the strings to init our THREE.Colors
let color1 = new THREE.Color(c1);
let color2 = new THREE.Color(c2);
for(let i = 0; i < positionAttribute.count; i++) {
vertex.fromBufferAttribute( positionAttribute, i );
// Now we can use them for color lerping
c.lerpColors( color1, color2, ( vertex.z - aabb.min.z) / f );
colorsArray.push(c.r, c.g, c.b); 
}