如何在 three.js 中使用 Three.Triangle()

Question

Three.js 有一个名为 THREE.Triangle() 的函数，我想知道如何使用它。

Answer 1

我怀疑三角形 class 可能不是您所期望的那样；它不是直接用于绘制简单 2D 三角形的 class。

三角形class是一个数学实用函数，用于封装三角形并进行计算，在绘制曲面时很有用。
关于在绘图表面中使用三角形的更详细的解释：Why do 3D engines primarily use triangles to draw surfaces?

如果您只是想绘制一个简单的二维三角形：

var geom = new THREE.Geometry();
var v1 = new THREE.Vector3(0,0,0);
var v2 = new THREE.Vector3(30,0,0);
var v3 = new THREE.Vector3(30,30,0);

geom.vertices.push(v1);
geom.vertices.push(v2);
geom.vertices.push(v3);

geom.faces.push( new THREE.Face3( 0, 1, 2 ) );
geom.computeFaceNormals();

var mesh= new THREE.Mesh( geom, new THREE.MeshNormalMaterial() );

对此的另一个 Whosebug 回答：Basic 2D colored triangle using three.js

使用三角形的等价代码class：

var geom = new THREE.Geometry();
var v1 = new THREE.Vector3(0,0,0);
var v2 = new THREE.Vector3(30,0,0);
var v3 = new THREE.Vector3(30,30,0);

var triangle = new THREE.Triangle( v1, v2, v3 );
var normal = triangle.normal();

// An example of getting the area from the Triangle class
console.log( 'Area of triangle is: '+ triangle.area() );

geom.vertices.push(triangle.a);
geom.vertices.push(triangle.b);
geom.vertices.push(triangle.c);

geom.faces.push( new THREE.Face3( 0, 1, 2, normal ) );

jsbin link 一起玩：http://jsbin.com/zatejelika/1/edit?html,css,js,output
三角形 class 文档 link：http://threejs.org/docs/#Reference/Math/Triangle

如何在 three.js 中使用 Three.Triangle()

How to use Three.Triangle() in three.js

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