Question

我正在尝试更改网格单个面上的颜色。这是在WebGL上下文中。我可以改变整个网格颜色，而不是单个面。相关代码如下：

// Updated Per Lee!

var camera = _this.camera;      
var projector = new THREE.Projector();
var vector = new THREE.Vector3( ( event.clientX / window.innerWidth ) * 2 - 1,                                  - ( event.clientY / window.innerHeight ) * 2 + 1, 0.5 );
projector.unprojectVector( vector, camera );

var ray = new THREE.Ray( camera.position, vector.subSelf( camera.position ).normalize() );
var intersects = ray.intersectObjects( kage.scene.children );

if ( intersects.length > 0 ) {
    face = intersects[0].face;
    var faceIndices = ['a', 'b', 'c', 'd'];         
    var numberOfSides = ( face instanceof THREE.Face3 ) ? 3 : 4;
    // assign color to each vertex of current face
    for( var j = 0; j < numberOfSides; j++ )  {
        var vertexIndex = face[ faceIndices[ j ] ];
    // initialize color variable
    var color = new THREE.Color( 0xffffff );
    color.setRGB( Math.random(), 0, 0 );
    face.vertexColors[ j ] = color;
    }
}

我也初始化了对象，在本例中是一个Cube，如下所示：

// this material causes a mesh to use colors assigned to vertices
var material = new THREE.MeshBasicMaterial( { 
    color: 0xf0f0f0, 
    shading: THREE.FlatShading,
    vertexColors: THREE.VertexColors 
});

var directionalLight = new THREE.DirectionalLight(0xEEEEEE);
directionalLight.position.set(10, 1, 1).normalize();
kage.scene.add(directionalLight);

var cube = new THREE.Mesh(new THREE.CubeGeometry(300, 300, 300,1,1,1), material);
cube.dynamic = true;
kage.scene.add(cube);

无论光线颜色如何，更改材质都会使立方体变白。交叉逻辑仍然有效，这意味着我选择了正确的面部，但唉颜色不会改变。

我是Stackoverflow的新手[很好问一个问题，希望我的编辑不会混淆]

Answer 1

将库更新到r53。
添加vertexColors: THREE.FaceColors 材料。
最后使用face.color.setRGB( Math.random(), Math.random(), Math.random())。

现在无需遍历4的循环 THREE.Face4或3边（a，b，c）的边（a，b，c，d） THREE.Face3。

这适用于WebGL和Canvas渲染。

Example

three.js r53

Answer 2

假设“myGeometry”是包含您想要更改颜色的面的几何体，“faceIndex”是您想要更改颜色的特定面的索引。

// the face's indices are labeled with these characters 
var faceIndices = ['a', 'b', 'c', 'd'];  

var face = myGeometry.faces[ faceIndex ];   

// determine if face is a tri or a quad
var numberOfSides = ( face instanceof THREE.Face3 ) ? 3 : 4;

// assign color to each vertex of current face
for( var j = 0; j < numberOfSides; j++ )  
{
    var vertexIndex = face[ faceIndices[ j ] ];
    // initialize color variable
    var color = new THREE.Color( 0xffffff );
    color.setRGB( Math.random(), 0, 0 );
    face.vertexColors[ j ] = color;
}

然后，网格需要使用以下材质，以便从顶点派生面颜色：

// this material causes a mesh to use colors assigned to vertices
var cubeMaterial = new THREE.MeshBasicMaterial( 
    { color: 0xffffff, shading: THREE.FlatShading, 
    vertexColors: THREE.VertexColors } );

Answer 3

我对three.js比较陌生，但这些例子中的大多数都显得过于冗长和复杂。以下代码似乎为立方体的所有12个三角形面做颜色...（WebGLRenderer r73）。

我在做这件事时注意到的一点是脸部的顺序有点奇怪（对我来说至少是新手）。

var geometry = new THREE.BoxGeometry( 1, 1, 1 );
console.log(geometry.faces.length); // 12 triangles
geometry.faces[0].color = new THREE.Color(0x000000); //Right 1
geometry.faces[1].color = new THREE.Color(0xFF0000); //Right 2
geometry.faces[2].color = new THREE.Color(0xFF8C08); //Left 1
geometry.faces[3].color = new THREE.Color(0xFFF702); //Left 2
geometry.faces[4].color = new THREE.Color(0x00FF00); //Top 1
geometry.faces[5].color = new THREE.Color(0x0000FF); //Top 2
geometry.faces[6].color = new THREE.Color(0x6F00FF); //Bottom 1
geometry.faces[7].color = new THREE.Color(0x530070); //Bottom 2
geometry.faces[8].color = new THREE.Color(0x3F3F3F); //Front 1
geometry.faces[9].color = new THREE.Color(0x6C6C6C); //Front 2
geometry.faces[10].color = new THREE.Color(0xA7A7A7);//Rear 1
geometry.faces[11].color = new THREE.Color(0xFFFFFF);//Rear 2

Answer 4

根据Three JS Geometry文档，要表示此面孔中的更新， Geometry.elementsNeedUpdate 需要设置为true。

以下代码段会更改所有面的颜色。

mesh.material.vertexColors = THREE.FaceColors

var faces = mesh.geometry.faces;

for(var i = 0 ; i < faces.length; i++){
  var face = faces[i];
  var color = new THREE.Color("rgb(255, 0, 0)");
  face.color = color;
}

mesh.geometry.elementsNeedUpdate = true;

render();

Answer 5

我认为上面列出的方法仅适用于WebGLRenderer。如果你想要在CanvasRenderer和WebGLRenderer中运行的东西有点复杂，但我怀疑最终结果在内存使用和性能方面都更有效。

在浏览THREE.jS Projector.js源代码后，我就是这样做的：

// create the face materials
var material_1 = new THREE.MeshLambertMaterial(
    {color : 0xff0000, shading: THREE.FlatShading, overdraw : true}
);
var material_2 = new THREE.MeshLambertMaterial(
    {color : 0x00ff00, shading: THREE.FlatShading, overdraw : true}
);

// create a geometry (any should do)
var geom = new THREE.CubeGeometry(1,1,1);

// add the materials directly to the geometry
geom.materials.push(material_1);
geom.materials.push(material_2);

// assign the material to individual faces (note you assign the index in 
// the geometry, not the material)
for( var i in geom.faces ) {
    var face = geom.faces[i];
    face.materialIndex = i%geom.materials.length;
}

// create a special material for your mesh that tells the renderer to use the 
// face materials
var material = new THREE.MeshFaceMaterial();
var mesh = new THREE.Mesh(geom, material);

这个例子是根据我的工作代码改编的，但是我不得不承认我实际上并没有运行这个确切的代码块，而且我没有很好的记录，首先要做好一切，但希望它将帮助任何挣扎的人

如何在Three.js中改变面部颜色

5 个答案: