本章用来作为Starling的滤镜实现原理的一个补充，但是为了了解原理，我们会使用原生API进行编码。

我们知道，当我们调用drawTriangles方法时，我们的图像是绘制到后台缓冲区的，只有调用present方法时才会把图像呈现到屏幕。

我们先来看看Context3D的两个方法：

  1. setRenderToTexture：我们默认的渲染都是在后台缓冲区进行的，使用该方法可以把渲染修改到一个纹理上，调用该方法后，Context3D对象的渲染操作（clear、drawTriangles等）都会渲染到指定的纹理上而不是后台缓冲区。
  2. setRenderToBackBuffer：配合setRenderToTexture的方法，可以将使用的缓冲区还原到后台缓冲区。

如果本章看不明白可以看这篇文章进行补充：stage3D 搭建2d图形引擎 （八） 动态纹理

先想一下我们的渲染过程：提交顶点数据和纹理，设定着色器和常量，最后调用drawTriangles配合索引缓冲进行绘制。

对于绘制到后台缓冲区的模型，我们就不能再次进行操作了，如果我们想要对一个模型进行多次不同的渲染就需要使用setRenderToTexture方法了。

先看看正常渲染的情况：

 package

 {

     import com.adobe.utils.AGALMiniAssembler;

     import flash.display.Bitmap;

     import flash.display.Sprite;

     import flash.display.Stage3D;

     import flash.display3D.Context3D;

     import flash.display3D.Context3DProfile;

     import flash.display3D.Context3DProgramType;

     import flash.display3D.Context3DRenderMode;

     import flash.display3D.Context3DTextureFormat;

     import flash.display3D.Context3DVertexBufferFormat;

     import flash.display3D.IndexBuffer3D;

     import flash.display3D.Program3D;

     import flash.display3D.VertexBuffer3D;

     import flash.display3D.textures.Texture;

     import flash.events.ErrorEvent;

     import flash.events.Event;

     [SWF(width=400, height=400, frameRate=60)]

     public class FilterDemo extends Sprite

     {

         [Embed(source="img.png")]

         private var IMG_CLASS:Class;

         private var _stage3D:Stage3D;

         private var _context3D:Context3D;

         private var _vertexBuffer:VertexBuffer3D;

         private var _indexBuffer:IndexBuffer3D;

         private var _texture:Texture;

         private var _program3D:Program3D;

         //会被作为目标渲染的纹理

         private var _filterTexture1:Texture;

         private var _filterTexture2:Texture;

         public function FilterDemo()

         {

             addEventListener(Event.ADDED_TO_STAGE, addedToStageHandler);

         }

         private function addedToStageHandler(event:Event):void

         {

             if(stage.stage3Ds.length > 0)

             {

                 _stage3D = stage.stage3Ds[0];

                 _stage3D.addEventListener(ErrorEvent.ERROR, stage3DErrorHandler);

                 _stage3D.addEventListener(Event.CONTEXT3D_CREATE, context3DCreateHandler);

                 _stage3D.requestContext3D(Context3DRenderMode.AUTO, Context3DProfile.BASELINE);

             }

         }

         private function stage3DErrorHandler(event:ErrorEvent):void

         {

             trace("Context3D对象请求失败：", event.text);

         }

         private function context3DCreateHandler(event:Event):void

         {

             initContext3D();

             initBuffer();

             initTexture();

             normalRander();

 //            filterRander1();

 //            filterRander2();

 //            finallyRander();

         }

         private function initContext3D():void

         {

             _context3D = _stage3D.context3D;

             _context3D.configureBackBuffer(400, 400, 2);

         }

         private function initBuffer():void

         {

             var vertexData:Vector.<Number> = Vector.<Number>(

                     [

                         -0.5, -0.5, 0, 0, 1,

                         0.5,  -0.5, 0, 1, 1,

                         0.5,   0.5, 0, 1, 0,

                         -0.5,  0.5, 0, 0, 0

                     ]);

             _vertexBuffer = _context3D.createVertexBuffer(vertexData.length / 5, 5);

             _vertexBuffer.uploadFromVector(vertexData, 0, vertexData.length / 5);

             var indexData:Vector.<uint> = Vector.<uint>(

                     [

                         0, 3, 1,

                         1, 2, 3

                     ]);

             _indexBuffer = _context3D.createIndexBuffer(indexData.length);

             _indexBuffer.uploadFromVector(indexData, 0, indexData.length);

         }

         private function initTexture():void

         {

             var bitmap:Bitmap = new IMG_CLASS() as Bitmap;

             _texture = _context3D.createTexture(128, 128, Context3DTextureFormat.BGRA, true);

             _texture.uploadFromBitmapData(bitmap.bitmapData, 0);

         }

         /**

          * 正常渲染.

          */

         private function normalRander():void

         {

             var vertexArr:Array =

                     [

                         "mov op, va0",

                         "mov v0, va1"

                     ];

             var fragmentArr:Array =

                     [

                         "tex ft0, v0, fs0 <2d,repeat,linear,nomip>",

                         "mov oc, ft0"

                     ];

             var assembler:AGALMiniAssembler = new AGALMiniAssembler();

             _program3D = assembler.assemble2(_context3D, 1, vertexArr.join("\n"), fragmentArr.join("\n"));

             _context3D.clear();

             _context3D.setVertexBufferAt(0, _vertexBuffer, 0, Context3DVertexBufferFormat.FLOAT_3);

             _context3D.setVertexBufferAt(1, _vertexBuffer, 3, Context3DVertexBufferFormat.FLOAT_2);

             _context3D.setTextureAt(0, _texture);

             _context3D.setProgram(_program3D);

             _context3D.drawTriangles(_indexBuffer);

             _context3D.present();

         }

         /**

          * 使用灰色滤镜渲染到纹理.

          */

         private function filterRander1():void

         {

             _filterTexture1 = _context3D.createTexture(128, 128, Context3DTextureFormat.BGRA, true);

             var vertexArr:Array =

                     [

                         "mov op, va0",

                         "mov v0, va1"

                     ];

             var fragmentArr:Array =

                     [

                         "tex ft0, v0, fs0 <2d,linear,clamp>",

                         "add ft1.x, ft0.x, ft0.y",

                         "add ft1.x, ft1.x, ft0.z",

                         "div ft1.x, ft1.x, fc0.w",

                         "mov ft0.xyz, ft1.xxx",

                         "mov oc ft0"

                     ];

             var assembler:AGALMiniAssembler = new AGALMiniAssembler();

             _program3D = assembler.assemble2(_context3D, 1, vertexArr.join("\n"), fragmentArr.join("\n"));

             //设定渲染目标为我们的纹理

             _context3D.setRenderToTexture(_filterTexture1);

             _context3D.clear();

             _context3D.setVertexBufferAt(0, _vertexBuffer, 0, Context3DVertexBufferFormat.FLOAT_3);

             _context3D.setVertexBufferAt(1, _vertexBuffer, 3, Context3DVertexBufferFormat.FLOAT_2);

             //传递到灰色滤镜的设定值

             _context3D.setProgramConstantsFromVector(Context3DProgramType.FRAGMENT, 0, Vector.<Number>([0.299, 0.587, 0.114, 3]));

             _context3D.setTextureAt(0, _texture);

             _context3D.setProgram(_program3D);

             _context3D.drawTriangles(_indexBuffer);

         }

         /**

          * 使用波浪滤镜再一次渲染到纹理.

          */

         private function filterRander2():void

         {

             _filterTexture2 = _context3D.createTexture(128, 128, Context3DTextureFormat.BGRA, true);

             var vertexArr:Array =

                     [

                         "mov op, va0",

                         "mov v0, va1"

                     ];

             var fragmentArr:Array =

                     [

                         "tex ft0,v0,fs0<2d,clamp,linear>",

                         "sub ft0.x,v0.x,fc0.w",

                         "mul ft0.x,ft0.x,ft0.x",

                         "sub ft0.y,v0.y,fc0.w",

                         "mul ft0.y,ft0.y,ft0.y",

                         "add ft0.z,ft0.x,ft0.y",

                         "sqt ft0.z,ft0.z",

                         "mul ft0.z,ft0.z,fc0.x",

                         "sub ft0.z,ft0.z,fc0.z",

                         "sin ft0.z,ft0.z",

                         "mul ft0.z,ft0.z,fc0.y",

                         "add ft0,v0,ft0.zzz",

                         "tex oc,ft0,fs0<2d,clamp,linear>"

                     ];

             var assembler:AGALMiniAssembler = new AGALMiniAssembler();

             _program3D = assembler.assemble2(_context3D, 1, vertexArr.join("\n"), fragmentArr.join("\n"));

             //设定渲染目标为我们的纹理

             _context3D.setRenderToTexture(_filterTexture2);

             _context3D.clear();

             _context3D.setVertexBufferAt(0, _vertexBuffer, 0, Context3DVertexBufferFormat.FLOAT_3);

             _context3D.setVertexBufferAt(1, _vertexBuffer, 3, Context3DVertexBufferFormat.FLOAT_2);

             //设置波浪的常量

             _context3D.setProgramConstantsFromVector(Context3DProgramType.FRAGMENT, 0, new <Number>[100, 0.01, 0, 0.5]);

             _context3D.setTextureAt(0, _filterTexture1);

             _context3D.setProgram(_program3D);

             _context3D.drawTriangles(_indexBuffer);

             //还原后台缓冲区为渲染目标

             _context3D.setRenderToBackBuffer();

         }

         /**

          * 把最终的结果渲染到舞台.

          */

         private function finallyRander():void

         {

             var vertexArr:Array =

                     [

                         "mov op, va0",

                         "mov v0, va1"

                     ];

             var fragmentArr:Array =

                     [

                         "tex ft0, v0, fs0 <2d,repeat,linear,nomip>",

                         "mov oc, ft0"

                     ];

             var assembler:AGALMiniAssembler = new AGALMiniAssembler();

             _program3D = assembler.assemble2(_context3D, 1, vertexArr.join("\n"), fragmentArr.join("\n"));

             _context3D.clear();

             _context3D.setVertexBufferAt(0, _vertexBuffer, 0, Context3DVertexBufferFormat.FLOAT_3);

             _context3D.setVertexBufferAt(1, _vertexBuffer, 3, Context3DVertexBufferFormat.FLOAT_2);

             _context3D.setTextureAt(0, _filterTexture2);

             _context3D.setProgram(_program3D);

             _context3D.drawTriangles(_indexBuffer);

             _context3D.present();

         }

     }

 }

下面是使用纹理渲染了2次滤镜的效果：

 package

 {

     import com.adobe.utils.AGALMiniAssembler;

     import flash.display.Bitmap;

     import flash.display.Sprite;

     import flash.display.Stage3D;

     import flash.display3D.Context3D;

     import flash.display3D.Context3DProfile;

     import flash.display3D.Context3DProgramType;

     import flash.display3D.Context3DRenderMode;

     import flash.display3D.Context3DTextureFormat;

     import flash.display3D.Context3DVertexBufferFormat;

     import flash.display3D.IndexBuffer3D;

     import flash.display3D.Program3D;

     import flash.display3D.VertexBuffer3D;

     import flash.display3D.textures.Texture;

     import flash.events.ErrorEvent;

     import flash.events.Event;

     [SWF(width=400, height=400, frameRate=60)]

     public class FilterDemo extends Sprite

     {

         [Embed(source="img.png")]

         private var IMG_CLASS:Class;

         private var _stage3D:Stage3D;

         private var _context3D:Context3D;

         private var _vertexBuffer:VertexBuffer3D;

         private var _indexBuffer:IndexBuffer3D;

         private var _texture:Texture;

         private var _program3D:Program3D;

         //会被作为目标渲染的纹理

         private var _filterTexture1:Texture;

         private var _filterTexture2:Texture;

         public function FilterDemo()

         {

             addEventListener(Event.ADDED_TO_STAGE, addedToStageHandler);

         }

         private function addedToStageHandler(event:Event):void

         {

             if(stage.stage3Ds.length > 0)

             {

                 _stage3D = stage.stage3Ds[0];

                 _stage3D.addEventListener(ErrorEvent.ERROR, stage3DErrorHandler);

                 _stage3D.addEventListener(Event.CONTEXT3D_CREATE, context3DCreateHandler);

                 _stage3D.requestContext3D(Context3DRenderMode.AUTO, Context3DProfile.BASELINE);

             }

         }

         private function stage3DErrorHandler(event:ErrorEvent):void

         {

             trace("Context3D对象请求失败：", event.text);

         }

         private function context3DCreateHandler(event:Event):void

         {

             initContext3D();

             initBuffer();

             initTexture();

 //            normalRander();

             filterRander1();

             filterRander2();

             finallyRander();

         }

         private function initContext3D():void

         {

             _context3D = _stage3D.context3D;

             _context3D.configureBackBuffer(400, 400, 2);

         }

         private function initBuffer():void

         {

             var vertexData:Vector.<Number> = Vector.<Number>(

                     [

                         -0.5, -0.5, 0, 0, 1,

                         0.5,  -0.5, 0, 1, 1,

                         0.5,   0.5, 0, 1, 0,

                         -0.5,  0.5, 0, 0, 0

                     ]);

             _vertexBuffer = _context3D.createVertexBuffer(vertexData.length / 5, 5);

             _vertexBuffer.uploadFromVector(vertexData, 0, vertexData.length / 5);

             var indexData:Vector.<uint> = Vector.<uint>(

                     [

                         0, 3, 1,

                         1, 2, 3

                     ]);

             _indexBuffer = _context3D.createIndexBuffer(indexData.length);

             _indexBuffer.uploadFromVector(indexData, 0, indexData.length);

         }

         private function initTexture():void

         {

             var bitmap:Bitmap = new IMG_CLASS() as Bitmap;

             _texture = _context3D.createTexture(128, 128, Context3DTextureFormat.BGRA, true);

             _texture.uploadFromBitmapData(bitmap.bitmapData, 0);

         }

         /**

          * 正常渲染.

          */

         private function normalRander():void

         {

             var vertexArr:Array =

                     [

                         "mov op, va0",

                         "mov v0, va1"

                     ];

             var fragmentArr:Array =

                     [

                         "tex ft0, v0, fs0 <2d,repeat,linear,nomip>",

                         "mov oc, ft0"

                     ];

             var assembler:AGALMiniAssembler = new AGALMiniAssembler();

             _program3D = assembler.assemble2(_context3D, 1, vertexArr.join("\n"), fragmentArr.join("\n"));

             _context3D.clear();

             _context3D.setVertexBufferAt(0, _vertexBuffer, 0, Context3DVertexBufferFormat.FLOAT_3);

             _context3D.setVertexBufferAt(1, _vertexBuffer, 3, Context3DVertexBufferFormat.FLOAT_2);

             _context3D.setTextureAt(0, _texture);

             _context3D.setProgram(_program3D);

             _context3D.drawTriangles(_indexBuffer);

             _context3D.present();

         }

         /**

          * 使用灰色滤镜渲染到纹理.

          */

         private function filterRander1():void

         {

             _filterTexture1 = _context3D.createTexture(128, 128, Context3DTextureFormat.BGRA, true);

             var vertexArr:Array =

                     [

                         "mov op, va0",

                         "mov v0, va1"

                     ];

             var fragmentArr:Array =

                     [

                         "tex ft0, v0, fs0 <2d,linear,clamp>",

                         "add ft1.x, ft0.x, ft0.y",

                         "add ft1.x, ft1.x, ft0.z",

                         "div ft1.x, ft1.x, fc0.w",

                         "mov ft0.xyz, ft1.xxx",

                         "mov oc ft0"

                     ];

             var assembler:AGALMiniAssembler = new AGALMiniAssembler();

             _program3D = assembler.assemble2(_context3D, 1, vertexArr.join("\n"), fragmentArr.join("\n"));

             //设定渲染目标为我们的纹理

             _context3D.setRenderToTexture(_filterTexture1);

             _context3D.clear();

             _context3D.setVertexBufferAt(0, _vertexBuffer, 0, Context3DVertexBufferFormat.FLOAT_3);

             _context3D.setVertexBufferAt(1, _vertexBuffer, 3, Context3DVertexBufferFormat.FLOAT_2);

             //传递到灰色滤镜的设定值

             _context3D.setProgramConstantsFromVector(Context3DProgramType.FRAGMENT, 0, Vector.<Number>([0.299, 0.587, 0.114, 3]));

             _context3D.setTextureAt(0, _texture);

             _context3D.setProgram(_program3D);

             _context3D.drawTriangles(_indexBuffer);

         }

         /**

          * 使用波浪滤镜再一次渲染到纹理.

          */

         private function filterRander2():void

         {

             _filterTexture2 = _context3D.createTexture(128, 128, Context3DTextureFormat.BGRA, true);

             var vertexArr:Array =

                     [

                         "mov op, va0",

                         "mov v0, va1"

                     ];

             var fragmentArr:Array =

                     [

                         "tex ft0,v0,fs0<2d,clamp,linear>",

                         "sub ft0.x,v0.x,fc0.w",

                         "mul ft0.x,ft0.x,ft0.x",

                         "sub ft0.y,v0.y,fc0.w",

                         "mul ft0.y,ft0.y,ft0.y",

                         "add ft0.z,ft0.x,ft0.y",

                         "sqt ft0.z,ft0.z",

                         "mul ft0.z,ft0.z,fc0.x",

                         "sub ft0.z,ft0.z,fc0.z",

                         "sin ft0.z,ft0.z",

                         "mul ft0.z,ft0.z,fc0.y",

                         "add ft0,v0,ft0.zzz",

                         "tex oc,ft0,fs0<2d,clamp,linear>"

                     ];

             var assembler:AGALMiniAssembler = new AGALMiniAssembler();

             _program3D = assembler.assemble2(_context3D, 1, vertexArr.join("\n"), fragmentArr.join("\n"));

             //设定渲染目标为我们的纹理

             _context3D.setRenderToTexture(_filterTexture2);

             _context3D.clear();

             _context3D.setVertexBufferAt(0, _vertexBuffer, 0, Context3DVertexBufferFormat.FLOAT_3);

             _context3D.setVertexBufferAt(1, _vertexBuffer, 3, Context3DVertexBufferFormat.FLOAT_2);

             //设置波浪的常量

             _context3D.setProgramConstantsFromVector(Context3DProgramType.FRAGMENT, 0, new <Number>[100, 0.01, 0, 0.5]);

             _context3D.setTextureAt(0, _filterTexture1);

             _context3D.setProgram(_program3D);

             _context3D.drawTriangles(_indexBuffer);

             //还原后台缓冲区为渲染目标

             _context3D.setRenderToBackBuffer();

         }

         /**

          * 把最终的结果渲染到舞台.

          */

         private function finallyRander():void

         {

             var vertexArr:Array =

                     [

                         "mov op, va0",

                         "mov v0, va1"

                     ];

             var fragmentArr:Array =

                     [

                         "tex ft0, v0, fs0 <2d,repeat,linear,nomip>",

                         "mov oc, ft0"

                     ];

             var assembler:AGALMiniAssembler = new AGALMiniAssembler();

             _program3D = assembler.assemble2(_context3D, 1, vertexArr.join("\n"), fragmentArr.join("\n"));

             _context3D.clear();

             _context3D.setVertexBufferAt(0, _vertexBuffer, 0, Context3DVertexBufferFormat.FLOAT_3);

             _context3D.setVertexBufferAt(1, _vertexBuffer, 3, Context3DVertexBufferFormat.FLOAT_2);

             _context3D.setTextureAt(0, _filterTexture2);

             _context3D.setProgram(_program3D);

             _context3D.drawTriangles(_indexBuffer);

             _context3D.present();

         }

     }

 }

我们发现最终的效果里我们的图像变小了很多，这是为啥呢？原因就是我们每次渲染时上传的顶点坐标是：

 var vertexData:Vector.<Number> = Vector.<Number>(

         [

             -0.5, -0.5, 0, 0, 1,

             0.5,  -0.5, 0, 1, 1,

             0.5,   0.5, 0, 1, 0,

             -0.5,  0.5, 0, 0, 0

         ]);

这样的结果是每次绘制图像都是占屏幕的一半，而我们经过3次渲染所以图像就变成了很小，要让图像不变的话，只有把顶点数据的0.5都改为1即可。

最终效果：

 package

 {

     import com.adobe.utils.AGALMiniAssembler;

     import flash.display.Bitmap;

     import flash.display.Sprite;

     import flash.display.Stage3D;

     import flash.display3D.Context3D;

     import flash.display3D.Context3DProfile;

     import flash.display3D.Context3DProgramType;

     import flash.display3D.Context3DRenderMode;

     import flash.display3D.Context3DTextureFormat;

     import flash.display3D.Context3DVertexBufferFormat;

     import flash.display3D.IndexBuffer3D;

     import flash.display3D.Program3D;

     import flash.display3D.VertexBuffer3D;

     import flash.display3D.textures.Texture;

     import flash.events.ErrorEvent;

     import flash.events.Event;

     [SWF(width=400, height=400, frameRate=60)]

     public class FilterDemo extends Sprite

     {

         [Embed(source="img.png")]

         private var IMG_CLASS:Class;

         private var _stage3D:Stage3D;

         private var _context3D:Context3D;

         private var _vertexBuffer:VertexBuffer3D;

         private var _indexBuffer:IndexBuffer3D;

         private var _texture:Texture;

         private var _program3D:Program3D;

         //会被作为目标渲染的纹理

         private var _filterTexture1:Texture;

         private var _filterTexture2:Texture;

         public function FilterDemo()

         {

             addEventListener(Event.ADDED_TO_STAGE, addedToStageHandler);

         }

         private function addedToStageHandler(event:Event):void

         {

             if(stage.stage3Ds.length > 0)

             {

                 _stage3D = stage.stage3Ds[0];

                 _stage3D.addEventListener(ErrorEvent.ERROR, stage3DErrorHandler);

                 _stage3D.addEventListener(Event.CONTEXT3D_CREATE, context3DCreateHandler);

                 _stage3D.requestContext3D(Context3DRenderMode.AUTO, Context3DProfile.BASELINE);

             }

         }

         private function stage3DErrorHandler(event:ErrorEvent):void

         {

             trace("Context3D对象请求失败：", event.text);

         }

         private function context3DCreateHandler(event:Event):void

         {

             initContext3D();

             initBuffer();

             initTexture();

 //            normalRander();

             filterRander1();

             filterRander2();

             finallyRander();

         }

         private function initContext3D():void

         {

             _context3D = _stage3D.context3D;

             _context3D.configureBackBuffer(400, 400, 2);

         }

         private function initBuffer():void

         {

             var vertexData:Vector.<Number> = Vector.<Number>(

                     [

                         -1, -1, 0, 0, 1,

                         1,  -1, 0, 1, 1,

                         1,   1, 0, 1, 0,

                         -1,  1, 0, 0, 0

                     ]);

             _vertexBuffer = _context3D.createVertexBuffer(vertexData.length / 5, 5);

             _vertexBuffer.uploadFromVector(vertexData, 0, vertexData.length / 5);

             var indexData:Vector.<uint> = Vector.<uint>(

                     [

                         0, 3, 1,

                         1, 2, 3

                     ]);

             _indexBuffer = _context3D.createIndexBuffer(indexData.length);

             _indexBuffer.uploadFromVector(indexData, 0, indexData.length);

         }

         private function initTexture():void

         {

             var bitmap:Bitmap = new IMG_CLASS() as Bitmap;

             _texture = _context3D.createTexture(128, 128, Context3DTextureFormat.BGRA, true);

             _texture.uploadFromBitmapData(bitmap.bitmapData, 0);

         }

         /**

          * 正常渲染.

          */

         private function normalRander():void

         {

             var vertexArr:Array =

                     [

                         "mov op, va0",

                         "mov v0, va1"

                     ];

             var fragmentArr:Array =

                     [

                         "tex ft0, v0, fs0 <2d,repeat,linear,nomip>",

                         "mov oc, ft0"

                     ];

             var assembler:AGALMiniAssembler = new AGALMiniAssembler();

             _program3D = assembler.assemble2(_context3D, 1, vertexArr.join("\n"), fragmentArr.join("\n"));

             _context3D.clear();

             _context3D.setVertexBufferAt(0, _vertexBuffer, 0, Context3DVertexBufferFormat.FLOAT_3);

             _context3D.setVertexBufferAt(1, _vertexBuffer, 3, Context3DVertexBufferFormat.FLOAT_2);

             _context3D.setTextureAt(0, _texture);

             _context3D.setProgram(_program3D);

             _context3D.drawTriangles(_indexBuffer);

             _context3D.present();

         }

         /**

          * 使用灰色滤镜渲染到纹理.

          */

         private function filterRander1():void

         {

             _filterTexture1 = _context3D.createTexture(128, 128, Context3DTextureFormat.BGRA, true);

             var vertexArr:Array =

                     [

                         "mov op, va0",

                         "mov v0, va1"

                     ];

             var fragmentArr:Array =

                     [

                         "tex ft0, v0, fs0 <2d,linear,clamp>",

                         "add ft1.x, ft0.x, ft0.y",

                         "add ft1.x, ft1.x, ft0.z",

                         "div ft1.x, ft1.x, fc0.w",

                         "mov ft0.xyz, ft1.xxx",

                         "mov oc ft0"

                     ];

             var assembler:AGALMiniAssembler = new AGALMiniAssembler();

             _program3D = assembler.assemble2(_context3D, 1, vertexArr.join("\n"), fragmentArr.join("\n"));

             //设定渲染目标为我们的纹理

             _context3D.setRenderToTexture(_filterTexture1);

             _context3D.clear();

             _context3D.setVertexBufferAt(0, _vertexBuffer, 0, Context3DVertexBufferFormat.FLOAT_3);

             _context3D.setVertexBufferAt(1, _vertexBuffer, 3, Context3DVertexBufferFormat.FLOAT_2);

             //传递到灰色滤镜的设定值

             _context3D.setProgramConstantsFromVector(Context3DProgramType.FRAGMENT, 0, Vector.<Number>([0.299, 0.587, 0.114, 3]));

             _context3D.setTextureAt(0, _texture);

             _context3D.setProgram(_program3D);

             _context3D.drawTriangles(_indexBuffer);

         }

         /**

          * 使用波浪滤镜再一次渲染到纹理.

          */

         private function filterRander2():void

         {

             _filterTexture2 = _context3D.createTexture(128, 128, Context3DTextureFormat.BGRA, true);

             var vertexArr:Array =

                     [

                         "mov op, va0",

                         "mov v0, va1"

                     ];

             var fragmentArr:Array =

                     [

                         "tex ft0,v0,fs0<2d,clamp,linear>",

                         "sub ft0.x,v0.x,fc0.w",

                         "mul ft0.x,ft0.x,ft0.x",

                         "sub ft0.y,v0.y,fc0.w",

                         "mul ft0.y,ft0.y,ft0.y",

                         "add ft0.z,ft0.x,ft0.y",

                         "sqt ft0.z,ft0.z",

                         "mul ft0.z,ft0.z,fc0.x",

                         "sub ft0.z,ft0.z,fc0.z",

                         "sin ft0.z,ft0.z",

                         "mul ft0.z,ft0.z,fc0.y",

                         "add ft0,v0,ft0.zzz",

                         "tex oc,ft0,fs0<2d,clamp,linear>"

                     ];

             var assembler:AGALMiniAssembler = new AGALMiniAssembler();

             _program3D = assembler.assemble2(_context3D, 1, vertexArr.join("\n"), fragmentArr.join("\n"));

             //设定渲染目标为我们的纹理

             _context3D.setRenderToTexture(_filterTexture2);

             _context3D.clear();

             _context3D.setVertexBufferAt(0, _vertexBuffer, 0, Context3DVertexBufferFormat.FLOAT_3);

             _context3D.setVertexBufferAt(1, _vertexBuffer, 3, Context3DVertexBufferFormat.FLOAT_2);

             //设置波浪的常量

             _context3D.setProgramConstantsFromVector(Context3DProgramType.FRAGMENT, 0, new <Number>[100, 0.01, 0, 0.5]);

             _context3D.setTextureAt(0, _filterTexture1);

             _context3D.setProgram(_program3D);

             _context3D.drawTriangles(_indexBuffer);

             //还原后台缓冲区为渲染目标

             _context3D.setRenderToBackBuffer();

         }

         /**

          * 把最终的结果渲染到舞台.

          */

         private function finallyRander():void

         {

             var vertexArr:Array =

                     [

                         "mov op, va0",

                         "mov v0, va1"

                     ];

             var fragmentArr:Array =

                     [

                         "tex ft0, v0, fs0 <2d,repeat,linear,nomip>",

                         "mov oc, ft0"

                     ];

             var assembler:AGALMiniAssembler = new AGALMiniAssembler();

             _program3D = assembler.assemble2(_context3D, 1, vertexArr.join("\n"), fragmentArr.join("\n"));

             _context3D.clear();

             _context3D.setVertexBufferAt(0, _vertexBuffer, 0, Context3DVertexBufferFormat.FLOAT_3);

             _context3D.setVertexBufferAt(1, _vertexBuffer, 3, Context3DVertexBufferFormat.FLOAT_2);

             _context3D.setTextureAt(0, _filterTexture2);

             _context3D.setProgram(_program3D);

             _context3D.drawTriangles(_indexBuffer);

             _context3D.present();

         }

     }

 }

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