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<Model>("cub");

//载入贴图纹理(暂时不使用)

text = Content.Load<Texture2D>("rocks");

//载入效果(暂时不使用)

 effe = Content.Load<Effect>("effe");

//设置效果的Technique

 effe.CurrentTechnique = effe.Techniques["technique1"];

}

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FillMode

 if (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:

图1

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:

图2

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POSITION

float4 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COLOR0

float4 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Technique

technique technique1

{

//一个pass

pass 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_main

PixelShader=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.Parameters["mWorldViewProjection"].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.Vertices[0].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:

图3

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.Parameters["World"].SetValue(world);

effe.Parameters["View"].SetValue(view);

effe.Parameters["Projection"].SetValue(projection);

//下面的参数text类型为Texture

effe.Parameters["diffuseTexture"].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.Vertices[0].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 = <diffuseTexture>;

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 PixelShaderFunction(VertexShaderOutput input) : COLOR0

{

return tex2D(DiffuseTextureSampler,input.uv);

}

technique technique1

{

pass Pass1

{

VertexShader = compile vs_1_1 VertexShaderFunction();

PixelShader = compile ps_1_1 PixelShaderFunction();

}

}

渲染效果如下图所示:

图4

就此,我也算对HLSL有了更近步的了解,以后在做的就是多多分析高手写好的HSLS代码。


发布时间:2008/9/5 7:33:41  阅读次数:10720

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