/src/aerys/minko/render/geometry/primitive/TorusGeometry.as

  1package aerys.minko.render.geometry.primitive 
  2{
  3	import aerys.minko.render.geometry.Geometry;
  4	import aerys.minko.render.geometry.stream.IVertexStream;
  5	import aerys.minko.render.geometry.stream.IndexStream;
  6	import aerys.minko.render.geometry.stream.StreamUsage;
  7	import aerys.minko.render.geometry.stream.VertexStream;
  8	import aerys.minko.render.geometry.stream.format.VertexComponent;
  9	import aerys.minko.render.geometry.stream.format.VertexFormat;
 10	
 11	import flash.utils.ByteArray;
 12	import flash.utils.Endian;
 13	
 14	public class TorusGeometry extends Geometry
 15	{
 16		private static const EPSILON	: Number	= 0.00001;
 17		private static const DTOR 		: Number	= 0.01745329252;
 18		
 19		private var _radius		: Number;
 20		private var _tube		: Number;
 21		private var _segmentsR	: uint;
 22		private var _segmentsT	: uint;
 23		private var _arc		: Number;
 24		
 25		public function TorusGeometry(radius				: Number	= .375,
 26									  tube					: Number	= .125,
 27									  segmentsR				: uint		= 14,
 28									  segmentsT				: uint		= 13,
 29									  arc					: Number	= Math.PI * 2.,
 30									  withUVs				: Boolean	= true,
 31									  withNormals			: Boolean	= true,
 32									  vertexStreamUsage		: uint		= 3,
 33									  indexStreamUsage		: uint		= 3)
 34		{
 35			_radius = radius;
 36			_tube = tube;
 37			_segmentsR = segmentsR;
 38			_segmentsT = segmentsT;
 39			_arc = arc;
 40			
 41			super(
 42				new <IVertexStream>[buildVertexStream(vertexStreamUsage, withUVs, withNormals)],
 43				buildIndexStream(indexStreamUsage)
 44			);
 45		}
 46		
 47		private function buildVertexStream(usage : uint, withUVs : Boolean, withNormals : Boolean) : VertexStream
 48		{
 49			var vertexData	: Vector.<Number>	= new <Number>[];
 50			
 51			for (var j : uint = 0; j <= _segmentsR; ++j)
 52			{
 53				for (var i : uint = 0; i <= _segmentsT; ++i)
 54				{
 55					var u 		: Number 	= i / _segmentsT * _arc;
 56					var v 		: Number 	= j / _segmentsR * _arc;
 57					var cosU	: Number	= Math.cos(u);
 58					var sinU	: Number	= Math.sin(u);
 59					var cosV	: Number	= Math.cos(v);
 60					var x		: Number	= (_radius + _tube * cosV) * cosU;
 61					var y		: Number	= (_radius + _tube * cosV) * sinU;
 62					var z		: Number	= _tube * Math.sin(v);
 63					
 64					vertexData.push(x, y, z);
 65					
 66					if (withUVs)
 67						vertexData.push(i / _segmentsT, 1 - j / _segmentsR);
 68					
 69					if (withNormals)
 70					{
 71						var normalX	: Number	= x - _radius * cosU;
 72						var normalY	: Number	= y - _radius * sinU;
 73						var normalZ	: Number	= z;
 74						var mag		: Number	= normalX * normalX + normalY * normalY
 75							+ normalZ * normalZ;
 76						
 77						normalX /= mag;
 78						normalY /= mag;
 79						normalZ /= mag;
 80						
 81						vertexData.push(normalX, normalY, normalZ);
 82					}
 83				}
 84			}
 85			
 86			var format : VertexFormat = new VertexFormat(VertexComponent.XYZ);
 87			
 88			if (withUVs)
 89				format.addComponent(VertexComponent.UV);
 90			
 91			if (withNormals)
 92				format.addComponent(VertexComponent.NORMAL);
 93			
 94			return VertexStream.fromVector(usage, format, vertexData);
 95		}
 96		
 97		private function buildIndexStream(usage : uint) : IndexStream
 98		{
 99			var indices : ByteArray = new ByteArray();
100			
101			indices.endian = Endian.LITTLE_ENDIAN;
102			for (var j : uint = 1; j <= _segmentsR; ++j)
103			{
104				for (var i : uint = 1; i <= _segmentsT; ++i)
105				{
106					var a : uint = (_segmentsT + 1) * j + i - 1;
107					var b : uint = (_segmentsT + 1) * (j - 1) + i - 1;
108					var c : uint = (_segmentsT + 1) * (j - 1) + i;
109					var d : uint = (_segmentsT + 1) * j + i;
110					
111					indices.writeShort(a);
112					indices.writeShort(c);
113					indices.writeShort(b);
114					indices.writeShort(a);
115					indices.writeShort(d);
116					indices.writeShort(c);
117				}
118			}
119			indices.position = 0;
120			
121			return new IndexStream(usage, indices);
122		}
123	}
124}