three.js 源碼註釋（七十七）extras/geometries/LatheGeometry.js

商域無疆 (http://blog.csdn.net/omni360/)

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轉載請保留此句：商域無疆 -  本博客專注於 敏捷開發及移動和物聯設備研究：數據可視化、GOLANG、Html5、WEBGL、THREE.JS，否則，出自本博客的文章拒絕轉載或再轉載，謝謝合作。

俺也是剛開始學,好多地兒肯定不對還請見諒.

以下代碼是THREE.JS 源碼文件中extras/geometries/LatheGeometry.js文件的註釋.

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類通過截面頂點數組(points)創建旋轉幾何體.
///
///	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">旋轉體截面頂點數組</param>
///<param name ="segments" type="int">旋轉體旋轉圓周的細分線段數</param>
///<param name ="phiStart" type="float">旋轉體的起始點</param>
///<param name ="phiLength" type="float">旋轉體的弧長</param>
// points - to create a closed torus, one must use a set of points //創建一個封閉的環面,
//    like so: [ a, b, c, d, a ], see first is the same as last.	//例如[a,b,c,d,a],第一個頂點必須和最後一個頂點相同.
// segments - the number of circumference segments to create //旋轉圓周的細分線段數
// phiStart - the starting radian 	//旋轉截面的起始點,默認初始化爲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. 	//旋轉的弧長默認初始化爲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;
	//旋轉體截面頂點數組通過旋轉,獲得所有的頂點數組.
	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;
	//將所有的頂點計算生成三角面,並計算出三角面貼圖的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();	//合併頂點,刪除多餘的頂點 
	this.computeFaceNormals();	//計算三角面的法線
	this.computeVertexNormals();	//計算頂點的法線

};
/*************************************************
****下面是LatheGeometry對象的方法屬性定義,繼承自Geometry對象.
**************************************************/
THREE.LatheGeometry.prototype = Object.create( THREE.Geometry.prototype );

商域無疆 (http://blog.csdn.net/omni360/)

本文遵循“署名-非商業用途-保持一致”創作公用協議

轉載請保留此句：商域無疆 -  本博客專注於 敏捷開發及移動和物聯設備研究：數據可視化、GOLANG、Html5、WEBGL、THREE.JS，否則，出自本博客的文章拒絕轉載或再轉載，謝謝合作。

以下代碼是THREE.JS 源碼文件中extras/geometries/LatheGeometry.js文件的註釋.

更多更新在 : https://github.com/omni360/three.js.sourcecode