问题
Trying to paint each cube face with a different color, I found a thread that presents a way to achieve this:
var geometry = new THREE.BoxGeometry(5, 5, 5);
for (var i = 0; i < geometry.faces.length; i++) {
geometry.faces[i].color.setHex(Math.random() * 0xffffff);
}
var material = new THREE.MeshBasicMaterial({
color: 0xffffff,
vertexColors: THREE.FaceColors
});
But with three.js r86, I get the following result:
Got the triangles that make up each face, painted individually.
To achieve the desirable effect, I used the following adaptation of the above code:
var geometry = new THREE.BoxGeometry(5, 5, 5);
for ( var i = 0; i < geometry.faces.length; i += 2 ) {
var faceColor = Math.random() * 0xffffff;
geometry.faces[i].color.setHex(faceColor);
geometry.faces[i+1].color.setHex(faceColor);
}
var material = new THREE.MeshBasicMaterial({
color: 0xffffff,
vertexColors: THREE.FaceColors
});
But this all seems a bit over worked!
'use strict';
var camera, scene, renderer, cube;
init();
render();
function init() {
scene = new THREE.Scene();
camera = new THREE.PerspectiveCamera(75, window.innerWidth / window.innerHeight, 0.1, 1000);
// renderer
renderer = new THREE.WebGLRenderer({
alpha: true
});
renderer.setSize(window.innerWidth, window.innerHeight);
document.body.appendChild(renderer.domElement);
camera.position.z = 12;
// Mesh - cube
var geometry = new THREE.BoxGeometry(5, 5, 5);
for (var i = 0; i < geometry.faces.length; i += 2) {
var faceColor = Math.random() * 0xffffff;
geometry.faces[i].color.setHex(faceColor);
geometry.faces[i + 1].color.setHex(faceColor);
}
var material = new THREE.MeshBasicMaterial({
color: 0xffffff,
vertexColors: THREE.FaceColors
});
cube = new THREE.Mesh(geometry, material);
scene.add(cube);
// Light
var pointLight = new THREE.PointLight(0xFFFFFF);
pointLight.position.x = 10;
pointLight.position.y = 50;
pointLight.position.z = 130;
scene.add(pointLight);
}
function render() {
cube.rotation.x = 16;
cube.rotation.y = 4;
cube.rotation.z -= 5;
renderer.render(scene, camera);
}body,
canvas {
margin: 0;
padding: 0;
}
body {
overflow: hidden;
background-color: #fff;
}<script src="https://cdnjs.cloudflare.com/ajax/libs/three.js/86/three.js"></script>Am I missing something on three.js to accomplish the face painting as a whole ?
回答1:
If you switch to BufferGeometry you can use groups to control the material of sections of your geometry. Groups are based on the vertex indices, and allow you to define a material index, which will reference a material inside an array of materials.
Consider:
// start, count, material index
bufferGeometry.addGroup(12, 6, 2)
This tells the geometry to start a new group of triangles at indices index 12, and accounts for 6 indices (which reference 6 vertices). The final parameter tells the group of triangles to use material index 2 (index 2 of the array of materials you use to create the mesh).
In the example below, I've given each side of a cube a different color. You might think this is the same effect as setting face colors, but note that this is setting a material per group, not just a color, which can lead to creating some really cool effects.
var renderer, scene, camera, controls, stats, mesh;
var WIDTH = window.innerWidth,
HEIGHT = window.innerHeight,
FOV = 35,
NEAR = 1,
FAR = 1000;
function populateScene() {
var bg = new THREE.BufferGeometry();
bg.addAttribute("position", new THREE.BufferAttribute(new Float32Array([
// front
-1, 1, 1, // 0
-1, -1, 1, // 1
1, 1, 1, // 2
1, -1, 1, // 3
// right
1, 1, 1, // 4
1, -1, 1, // 5
1, 1, -1, // 6
1, -1, -1, // 7
// back
1, 1, -1, // 8
1, -1, -1, // 9
-1, 1, -1, // 10
-1, -1, -1, // 11
// left
-1, 1, -1, // 12
-1, -1, -1, // 13
-1, 1, 1, // 14
-1, -1, 1, // 15
// top
-1, 1, -1, // 16
-1, 1, 1, // 17
1, 1, -1, // 18
1, 1, 1, // 19
// bottom
-1, -1, 1, // 20
-1, -1, -1, // 21
1, -1, 1, // 22
1, -1, -1 // 23
]), 3));
bg.addAttribute("normal", new THREE.BufferAttribute(new Float32Array([
// front
0, 0, 1, // 0
0, 0, 1, // 1
0, 0, 1, // 2
0, 0, 1, // 3
// right
1, 0, 0, // 4
1, 0, 0, // 5
1, 0, 0, // 6
1, 0, 0, // 7
// back
0, 0, -1, // 8
0, 0, -1, // 9
0, 0, -1, // 10
0, 0, -1, // 11
// left
-1, 0, 0, // 12
-1, 0, 0, // 13
-1, 0, 0, // 14
-1, 0, 0, // 15
// top
0, 1, 0, // 16
0, 1, 0, // 17
0, 1, 0, // 18
0, 1, 0, // 19
// bottom
0, -1, 0, // 20
0, -1, 0, // 21
0, -1, 0, // 22
0, -1, 0 // 23
]), 3));
bg.setIndex(new THREE.BufferAttribute(new Uint32Array([
// front 0
0, 1, 2,
3, 2, 1,
// right 6
4, 5, 6,
7, 6, 5,
// back 12
8, 9, 10,
11, 10, 9,
// left 18
12, 13, 14,
15, 14, 13,
// top 24
16, 17, 18,
19, 18, 17,
// bottom 30
20, 21, 22,
23, 22, 21
]), 1));
bg.clearGroups();
// start, count, material index
bg.addGroup(0, 6, 0);
bg.addGroup(6, 6, 1);
bg.addGroup(12, 6, 2);
bg.addGroup(18, 6, 3);
bg.addGroup(24, 6, 4);
bg.addGroup(30, 6, 5);
var materials = [
new THREE.MeshLambertMaterial({color:"red"}),
new THREE.MeshLambertMaterial({color:"green"}),
new THREE.MeshLambertMaterial({color:"blue"}),
new THREE.MeshLambertMaterial({color:"cyan"}),
new THREE.MeshLambertMaterial({color:"magenta"}),
new THREE.MeshLambertMaterial({color:"yellow"})
];
mesh = new THREE.Mesh(bg, materials);
mesh.scale.set(5, 5, 5);
scene.add(mesh);
}
function init() {
document.body.style.backgroundColor = "slateGray";
renderer = new THREE.WebGLRenderer({
antialias: true,
alpha: true
});
renderer.shadowMap.enabled = true;
renderer.shadowMap.type = THREE.PCFSoftShadowMap;
document.body.appendChild(renderer.domElement);
document.body.style.overflow = "hidden";
document.body.style.margin = "0";
document.body.style.padding = "0";
scene = new THREE.Scene();
camera = new THREE.PerspectiveCamera(FOV, WIDTH / HEIGHT, NEAR, FAR);
camera.position.z = 50;
scene.add(camera);
controls = new THREE.TrackballControls(camera, renderer.domElement);
controls.dynamicDampingFactor = 0.5;
controls.rotateSpeed = 3;
var light = new THREE.PointLight(0xffffff, 1, Infinity);
camera.add(light);
stats = new Stats();
stats.domElement.style.position = 'absolute';
stats.domElement.style.top = '0';
document.body.appendChild(stats.domElement);
resize();
window.onresize = resize;
populateScene();
animate();
}
function resize() {
WIDTH = window.innerWidth;
HEIGHT = window.innerHeight;
if (renderer && camera && controls) {
renderer.setSize(WIDTH, HEIGHT);
camera.aspect = WIDTH / HEIGHT;
camera.updateProjectionMatrix();
controls.handleResize();
}
}
function render() {
renderer.render(scene, camera);
}
function animate() {
mesh.rotation.x += 0.015;
mesh.rotation.y += 0.017;
mesh.rotation.z += 0.019;
requestAnimationFrame(animate);
render();
controls.update();
stats.update();
}
function threeReady() {
init();
}
(function() {
function addScript(url, callback) {
callback = callback || function() {};
var script = document.createElement("script");
script.addEventListener("load", callback);
script.setAttribute("src", url);
document.head.appendChild(script);
}
addScript("https://threejs.org/build/three.js", function() {
addScript("https://threejs.org/examples/js/controls/TrackballControls.js", function() {
addScript("https://threejs.org/examples/js/libs/stats.min.js", function() {
threeReady();
})
})
})
})();Edit: Adding a second example using the base BoxBufferGeometry
Based on pailhead's comment to the original post, here's a snippet which uses unmodified BoxBufferGeometry. But as they mentioned in their comment, you'll still need to know which group corresponds to which face.
var renderer, scene, camera, controls, stats, mesh;
var WIDTH = window.innerWidth,
HEIGHT = window.innerHeight,
FOV = 35,
NEAR = 1,
FAR = 1000;
function populateScene() {
var bg = new THREE.BoxBufferGeometry(1, 1, 1);
var materials = [
new THREE.MeshLambertMaterial({color:"red"}),
new THREE.MeshLambertMaterial({color:"green"}),
new THREE.MeshLambertMaterial({color:"blue"}),
new THREE.MeshLambertMaterial({color:"cyan"}),
new THREE.MeshLambertMaterial({color:"magenta"}),
new THREE.MeshLambertMaterial({color:"yellow"})
];
mesh = new THREE.Mesh(bg, materials);
mesh.scale.set(10, 10, 10);
scene.add(mesh);
}
function init() {
document.body.style.backgroundColor = "slateGray";
renderer = new THREE.WebGLRenderer({
antialias: true,
alpha: true
});
renderer.shadowMap.enabled = true;
renderer.shadowMap.type = THREE.PCFSoftShadowMap;
document.body.appendChild(renderer.domElement);
document.body.style.overflow = "hidden";
document.body.style.margin = "0";
document.body.style.padding = "0";
scene = new THREE.Scene();
camera = new THREE.PerspectiveCamera(FOV, WIDTH / HEIGHT, NEAR, FAR);
camera.position.z = 50;
scene.add(camera);
controls = new THREE.TrackballControls(camera, renderer.domElement);
controls.dynamicDampingFactor = 0.5;
controls.rotateSpeed = 3;
var light = new THREE.PointLight(0xffffff, 1, Infinity);
camera.add(light);
stats = new Stats();
stats.domElement.style.position = 'absolute';
stats.domElement.style.top = '0';
document.body.appendChild(stats.domElement);
resize();
window.onresize = resize;
populateScene();
animate();
}
function resize() {
WIDTH = window.innerWidth;
HEIGHT = window.innerHeight;
if (renderer && camera && controls) {
renderer.setSize(WIDTH, HEIGHT);
camera.aspect = WIDTH / HEIGHT;
camera.updateProjectionMatrix();
controls.handleResize();
}
}
function render() {
renderer.render(scene, camera);
}
function animate() {
mesh.rotation.x += 0.015;
mesh.rotation.y += 0.017;
mesh.rotation.z += 0.019;
requestAnimationFrame(animate);
render();
controls.update();
stats.update();
}
function threeReady() {
init();
}
(function() {
function addScript(url, callback) {
callback = callback || function() {};
var script = document.createElement("script");
script.addEventListener("load", callback);
script.setAttribute("src", url);
document.head.appendChild(script);
}
addScript("https://threejs.org/build/three.js", function() {
addScript("https://threejs.org/examples/js/controls/TrackballControls.js", function() {
addScript("https://threejs.org/examples/js/libs/stats.min.js", function() {
threeReady();
})
})
})
})();来源：https://stackoverflow.com/questions/44828713/paint-cube-faces-as-a-whole-not-the-triangles-that-make-up-the-face-three-js