如何在three.js中使用Three.Triangle()

Question

Three.js有函数调用THREE.Triangle(),我想知道如何使用它.

Answer 1

我怀疑Triangle课程可能不是你所期望的那样; 它不是一个直接用于绘制简单2D三角形的类.

Triangle类是一个数学效用函数,用于封装三角形和进行计算,这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:为什么3D引擎主要使用三角形来绘制曲面？

如果您只是想绘制一个简单的2D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() );

另一个StackOverflow答案:使用three.js的基本2D彩色三角形

使用Triangle类的等效代码:

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链接玩:http://jsbin.com/zatejelika/1/edit？html,css,js,output
三角类文档链接:http://threejs.org/docs/#Reference/Math/Triangle