标签：webgl 三维 数据可视化 three.js web3d
商域无疆 (http://blog.csdn.net/omni360/)
本文遵循“署名-非商业用途-保持一致”创作公用协议
转载请保留此句：商域无疆 - 本博客专注于 敏捷开发及移动和物联设备研究：数据可视化、GOLANG、Html5、WEBGL、THREE.JS，否则，出自本博客的文章拒绝转载或再转载，谢谢合作。
俺也是刚开始学,好多地儿肯定不对还请见谅.
以下代码是THREE.JS 源码文件中extras/geometries/LatheGeometry.js文件的注释.
更多更新在 : https://github.com/omni360/three.js.sourcecode
/**
* @author astrodud / http://astrodud.isgreat.org/
* @author zz85 / https://github.com/zz85
* @author bhouston / http://exocortex.com
*/
/*
///LatheGeometry类通过截面顶点数组(points)创建旋转几何体.
///
/// 用法:
/// var points = [];
/// for ( var i = 0; i < 10; i ++ ) {
/// points.push( new THREE.Vector3( Math.sin( i * 0.2 ) * 15 + 50, 0, ( i - 5 ) * 2 ) );
/// }
/// var geometry = new THREE.LatheGeometry( points );
/// var material = new THREE.MeshBasicMaterial( { color: 0xffff00 } );
/// var lathe = new THREE.Mesh( geometry, material );
/// scene.add( lathe );
*/
///<summary>LatheGeometry</summary>
///<param name ="points" type="float">旋转体截面顶点数组</param>
///<param name ="segments" type="int">旋转体旋转圆周的细分线段数</param>
///<param name ="phiStart" type="float">旋转体的起始点</param>
///<param name ="phiLength" type="float">旋转体的弧长</param>
// points - to create a closed torus, one must use a set of points //创建一个封闭的环面,
// like so: [ a, b, c, d, a ], see first is the same as last. //例如[a,b,c,d,a],第一个顶点必须和最后一个顶点相同.
// segments - the number of circumference segments to create //旋转圆周的细分线段数
// phiStart - the starting radian //旋转截面的起始点,默认初始化为0.
// phiLength - the radian (0 to 2*PI) range of the lathed section
// 2*pi is a closed lathe, less than 2PI is a portion. //旋转的弧长默认初始化为2*PI.
THREE.LatheGeometry = function ( points, segments, phiStart, phiLength ) {
THREE.Geometry.call( this );
segments = segments || 12;
phiStart = phiStart || 0;
phiLength = phiLength || 2 * Math.PI;
var inversePointLength = 1.0 / ( points.length - 1 );
var inverseSegments = 1.0 / segments;
//旋转体截面顶点数组通过旋转,获得所有的顶点数组.
for ( var i = 0, il = segments; i <= il; i ++ ) {
var phi = phiStart + i * inverseSegments * phiLength;
var c = Math.cos( phi ),
s = Math.sin( phi );
for ( var j = 0, jl = points.length; j < jl; j ++ ) {
var pt = points[ j ];
var vertex = new THREE.Vector3();
vertex.x = c * pt.x - s * pt.y;
vertex.y = s * pt.x + c * pt.y;
vertex.z = pt.z;
this.vertices.push( vertex );
}
}
var np = points.length;
//将所有的顶点计算生成三角面,并计算出三角面贴图的uv
for ( var i = 0, il = segments; i < il; i ++ ) {
for ( var j = 0, jl = points.length - 1; j < jl; j ++ ) {
var base = j + np * i;
var a = base;
var b = base + np;
var c = base + 1 + np;
var d = base + 1;
var u0 = i * inverseSegments;
var v0 = j * inversePointLength;
var u1 = u0 + inverseSegments;
var v1 = v0 + inversePointLength;
this.faces.push( new THREE.Face3( a, b, d ) );
this.faceVertexUvs[ 0 ].push( [
new THREE.Vector2( u0, v0 ),
new THREE.Vector2( u1, v0 ),
new THREE.Vector2( u0, v1 )
] );
this.faces.push( new THREE.Face3( b, c, d ) );
this.faceVertexUvs[ 0 ].push( [
new THREE.Vector2( u1, v0 ),
new THREE.Vector2( u1, v1 ),
new THREE.Vector2( u0, v1 )
] );
}
}
this.mergeVertices(); //合并顶点,删除多余的顶点
this.computeFaceNormals(); //计算三角面的法线
this.computeVertexNormals(); //计算顶点的法线
};
/*************************************************
****下面是LatheGeometry对象的方法属性定义,继承自Geometry对象.
**************************************************/
THREE.LatheGeometry.prototype = Object.create( THREE.Geometry.prototype );
商域无疆 (http://blog.csdn.net/omni360/)
本文遵循“署名-非商业用途-保持一致”创作公用协议
转载请保留此句：商域无疆 - 本博客专注于 敏捷开发及移动和物联设备研究：数据可视化、GOLANG、Html5、WEBGL、THREE.JS，否则，出自本博客的文章拒绝转载或再转载，谢谢合作。
以下代码是THREE.JS 源码文件中extras/geometries/LatheGeometry.js文件的注释.
更多更新在 : https://github.com/omni360/three.js.sourcecode
three.js 源码注释（七十七）extras/geometries/LatheGeometry.js
标签：webgl 三维 数据可视化 three.js web3d
原文地址：http://blog.csdn.net/omni360/article/details/43320785
