XNA中的HLSL简单应用.doc

XNA中的HLSL简单应用 以前一直没搞明白HLSL，最近两天苦下功夫，终于算是学到了HLSL入门了。这里我将通过对一个矩形模型以BassicEffect贴图和通过HLSL贴图作对比，从而掌握在XNA中使用.fx效果文件，和初步了解HLSL。下面先分析一下没有使用贴图时的代码： public class Game1 : Game GraphicsDeviceManager graphics; SpriteBatch spriteBatch; /投影矩阵 Matrix projection;/观察矩阵 Matrix view;/矩形的世界矩阵 Matrix world; /矩形模型 Model cub; /定义贴图纹理和效果（先声明，暂时不使用）Texture2D text; Effect effe; /是否在暂停状态bool isPause = false;KeyboardState preks = Keyboard.GetState(); public Game1() graphics = new GraphicsDeviceManager(this); Content.RootDirectory = Content; protected override void Initialize()/初始化投影矩阵projection=Matrix.CreatePerspectiveFieldOfView(MathHelper.PiOver4, GraphicsDevice.Viewport.AspectRatio, 1f, 100000f); /初始化观察矩阵view = Matrix.CreateLookAt(Vector3.Forward * 500, Vector3.Zero, Vector3.Up); /初始化矩形的世界矩阵world = Matrix.Identity; base.Initialize(); protected override void LoadContent() / Create a new SpriteBatch, which can be used to draw textures. spriteBatch = new SpriteBatch(GraphicsDevice); /载入矩形模型 cub = Content.Load(cub);/载入贴图纹理（暂时不使用）text = Content.Load(rocks); /载入效果（暂时不使用）effe = Content.Load(effe); /设置效果的Techniqueeffe.CurrentTechnique = effe.Techniquestechnique1; protected override void Update(GameTime gameTime)/当前按键状态KeyboardState ks = Keyboard.GetState(); /按S镜头拉远，W镜头拉近if (ks.IsKeyDown(Keys.S) view *= Matrix.CreateTranslation(-10 * Vector3.UnitZ); if (ks.IsKeyDown(Keys.W) view *= Matrix.CreateTranslation(10 * Vector3.UnitZ); /通过空格键控制是否暂停if (ks.IsKeyDown(Keys.Space) & preks.IsKeyUp(Keys.Space) if (isPause) isPause = false; else isPause = true; /控制FillModeif (ks.IsKeyDown(Keys.A) & preks.IsKeyUp(Keys.A) GraphicsDevice.RenderState.FillMode = FillMode.WireFrame; if (ks.IsKeyDown(Keys.Q) & preks.IsKeyUp(Keys.Q) GraphicsDevice.RenderState.FillMode = FillMode.Solid; preks = ks; /如果不是暂停状态，自动旋转矩形的世界矩阵，实现旋转效果 if (!isPause) world *= Matrix.CreateFromAxisAngle(new Vector3(1, 1, -1), gameTime.ElapsedGameTime.Ticks * 0.0000001f); base.Update(gameTime); protected override void Draw(GameTime gameTime) graphics.GraphicsDevice.Clear(Color.CornflowerBlue); foreach (ModelMesh mesh in cub.Meshes) foreach (BasicEffect effect in mesh.Effects) effect.World = world;effect.View = view; effect.Projection = projection; effect.EnableDefaultLighting(); mesh.Draw(); base.Draw(gameTime); 可以看到程序的效果如下：现在我们为例子加入贴图（即前面声名的Texture），因为是使用的Basiceffect类的方法，所以很简单，只需要在foreach (BasicEffect effect in mesh.Effects)的循环体中插入以下代码， effect.TextureEnabled = true; effect.Texture = text; 再来看一下效果：上面就是XNA中最简单的纹理贴图的方法，下面就将进入主要的部分HLSL渲染。首先看一段很经典的HLSL代码：/声明一个4x4的矩阵。传入的参数是世界、观察、投影矩阵的积float4x4 mWorldViewProjection; /定义一个VertexShader函数，作为入口，并返回值的语义为POSITIONfloat4 vs_main(float4 position:POSITION):POSITION /将传入的坐标顶点与世界观察投影矩阵相乘，一交完成三个顶点的交换return mul(position,mWorldViewProjection); /定义一个PixelShader函数，作为入口，并定义返回语义为COLOR0float4 ps_main():COLOR0 /固定返回白色作为显示颜色 Return float4(1,1,1,1); /开始定义Techniquetechnique technique1 /一个passpass pass0 /将VertexShader的版本设置为1.1，并将执行函数设置为vs_main VertexShader=compile vs_1_1 vs_main(); /将PixelShader的版本设置为1.1，并将执行函数设置为ps_mainPixelShader=compile ps_1_1 ps_main(); 这段代码中包含了一个全局变量，两个全局函数。这两个全局函数分别用于VertexShader和PixelShader，也直接作为VertexShader和PixelShader的入口函数。而全局变量则用在了VertexShader的计算中。代码中定义了一个technique并且包含了一个pass，在这个pass中VertexShader和PixelShader的版本都是1.1。使用这段代码去渲染任何一个模型，得到的都是一个白色的物体。在XNA中使用HLSL的代码如下：protected override void Draw(GameTime gameTime)graphics.GraphicsDevice.Clear(Color.CornflowerBlue); /设置HLSL参数effe.ParametersmWorldViewProjection.SetValue(world * view * projection); effe.Begin();foreach (EffectPass pass in effe.CurrentTechnique.Passes) pass.Begin();foreach (ModelMesh mesh in cub.Meshes) foreach (ModelMeshPart part in mesh.MeshParts) GraphicsDevice.VertexDeclaration = part.VertexDeclaration;GraphicsDevice.Indices = mesh.IndexBuffer;GraphicsDevice.Vertices0.SetSource(mesh.VertexBuffer,part.StartIndex, part.VertexStride);GraphicsDevice.DrawIndexedPrimitives(PrimitiveType.TriangleList, part.BaseVertex, 0, part.NumVertices, part.StartIndex, part.PrimitiveCount); pass.End();effe.End(); base.Draw(gameTime); 效果如下图： 让我们再近一步，用HLSL为我们的贴上纹理。修改Draw方法如下： protected override void Draw(GameTime gameTime) graphics.GraphicsDevice.Clear(Color.CornflowerBlue);effe.ParametersWorld.SetValue(world); effe.ParametersView.SetValue(view); effe.ParametersProjection.SetValue(projection); /下面的参数text类型为Textureeffe.ParametersdiffuseTexture.SetValue(text);effe.Begin();foreach (EffectPass pass in effe.CurrentTechnique.Passes) pass.Begin(); foreach (ModelMesh mesh in cub.Meshes) foreach (ModelMeshPart part in mesh.MeshParts) GraphicsDevice.VertexDeclaration = part.VertexDeclaration; GraphicsDevice.Indices = mesh.IndexBuffer; GraphicsDevice.Vertices0.SetSource(mesh.VertexBuffer, part.StartIndex, part.VertexStride); GraphicsDevice.DrawIndexedPrimitives(PrimitiveType.TriangleList, part.BaseVertex, 0, part.NumVertices, part.StartIndex, part.PrimitiveCount); pass.End(); effe.End(); base.Draw(gameTime); HLSL代码如下：float4x4 World; float4x4 View;float4x4 Projection; texture diffuseTexture:Diffuse; sampler DiffuseTextureSampler = sampler_state Texture = ; MinFilter=linear; MagFilter=linear;MipFilter=linear; ; struct VertexShaderInput float4 Position : POSITION0; float3 normal:NORMAL;float2 uv:TEXCOORD0; ;struct VertexShaderOutput float4 Position : POSITION0; float2 uv:TEXCOORD0; ; VertexShaderOutput VertexShaderFunction(VertexShaderInput input) VertexShaderOutput output; float4 worldPosition = mul(input.Position, World); float4 viewPosition = mul(worldPosition, View); output.Position = mul(viewPosition, Projection); output.uv=input.uv; return output; float4 P