XNA 天空盒子

今天终于做了个SkyBox,本来很简单，但是因为之前没有做过，所以做的候还是不是很顺利。

Skyboxr 原理很简单：

将6张图贴在个面上，图实为TextureCUBE。

首先为了省去每次写DEMO时都要重新写Camera的操作的方法，所有这次就做了个Camera操作的类，来封装Camera的常用操作方法：

 

Code

    using System;
using System.Collections.Generic;
using Microsoft.Xna.Framework;
using Microsoft.Xna.Framework.Audio;
using Microsoft.Xna.Framework.Content;
using Microsoft.Xna.Framework.GamerServices;
using Microsoft.Xna.Framework.Graphics;
using Microsoft.Xna.Framework.Input;
using Microsoft.Xna.Framework.Media;
using Microsoft.Xna.Framework.Net;
using Microsoft.Xna.Framework.Storage;

namespace CameraLib
{
 public class Camera
 {
 float Fov;
 float aspectRatio;
 float neer;
 float far;

 Vector3 mPosi;
 public Vector3 mposi{get{return mPosi;}}
 Vector3 mTarget;
 public Vector3 mtarget { get { return mTarget; } }
 Vector3 mUp;
 public Vector3 mup { get { return mUp; } }


 private Matrix view;
 public Matrix View
 {
 get { return Matrix.CreateLookAt(mPosi, mTarget, mUp); }
 }

 private Matrix projection;
 public Matrix Projection
 {
 get { return projection = Matrix.CreatePerspectiveFieldOfView(Fov, aspectRatio, neer, far); }
 }

 public Camera(float fov, float ar, float neer, float far,Vector3 pos,Vector3 targ,Vector3 up)
 {
 Fov = fov;
 this.aspectRatio = ar;
 this.neer = neer;
 this.far = far;

 this.mPosi = pos;
 this.mTarget = targ;
 this.mUp = up;

 UpdateMatrix();
 }

 Matrix tranMatrix = Matrix.Identity;
 public void UpdateMatrix()
 {
 KeyboardState ks = Keyboard.GetState();

 Vector3 movVec = Vector3.Zero;
 Vector3 rolVec = Vector3.Zero;
 
 #region 相机平移


 if (ks.IsKeyDown(Keys.W))
 {
 movVec.Z -= 1;
 }
 if (ks.IsKeyDown(Keys.S))
 {
 movVec.Z += 1;
 }

 if (ks.IsKeyDown(Keys.A))
 {
 movVec.X -= 1; 
 }
 if (ks.IsKeyDown(Keys.D))
 {
 movVec.X += 1;
 }

 if (ks.IsKeyDown(Keys.Q))
 {
 movVec.Y -= 1;
 }
 if (ks.IsKeyDown(Keys.E))
 {
 movVec.Y += 1;
 }

 #endregion

 #region 相机旋转

 if (ks.IsKeyDown(Keys.Left))
 {
 rolVec.Y+=0.1f;
 }
 if (ks.IsKeyDown(Keys.Right))
 {
 rolVec.Y-=0.1f;
 }
 if (ks.IsKeyDown(Keys.Up))
 {
 rolVec.X+=0.1f;
 }
 if (ks.IsKeyDown(Keys.Down))
 {
 rolVec.X-=0.1f;
 }

 if (ks.IsKeyDown(Keys.PageUp))
 {
 rolVec.Z+=0.1f;
 }
 if (ks.IsKeyDown(Keys.PageDown))
 {
 rolVec.Z-=0.1f;
 }

 #endregion
 tranMatrix *= Matrix.CreateRotationX(rolVec.X) * Matrix.CreateRotationY(rolVec.Y) * Matrix.CreateRotationZ(rolVec.Z);
 mUp = Vector3.Transform(Vector3.Up, tranMatrix);
 mPosi += Vector3.Transform(movVec, tranMatrix);

 mTarget = mPosi + Vector3.Transform(Vector3.Forward, tranMatrix);
 }

 private void cameraTransform(Matrix matrix)
 {
 view *= matrix;
 }
 }
}

 

 

这个类现在可能还不完善，以后要用的时候再修改吧。

接下来是shader：

 

Code

    float4x4 World;
float4x4 View;
float4x4 Projection;

float3 eyePosition:CameraPosition;

Texture textu;
samplerCUBE textuSampler=sampler_state
{
 texture=<textu>;
};

struct vsin
{
 float4 position:POSITION0;
 //float3 normal:NORMAL0;
 float2 texcoord:TEXCOORD0;
};

struct vsout
{
 float4 Position : POSITION0;
 float3 ViewDirection : TEXCOORD2;
};

vsout vs(vsin input)
{
 vsout output;
 output.Position=mul(input.position,mul(mul(World,View),Projection));
 output.ViewDirection=eyePosition-mul(input.position,World);
 return output;
}

struct psin
{
 float3 ViewDirection:TEXCOORD2;
};

float4 ps(psin input):COLOR0
{
 float3 vd=normalize(input.ViewDirection);
 return texCUBE(textuSampler,-vd);
}


technique Technique1
{
 pass Pass1
 {
 VertexShader = compile vs_3_0 vs();
 PixelShader = compile ps_3_0 ps();
 }
} 
 

 

 

注意：这里出来后，当你移动镜头时，可能看到skybox的移动方向可能和实际方向相反。

然后是主程序：

 

Code

    using System;
using System.Collections.Generic;
using System.Linq;
using Microsoft.Xna.Framework;
using Microsoft.Xna.Framework.Audio;
using Microsoft.Xna.Framework.Content;
using Microsoft.Xna.Framework.GamerServices;
using Microsoft.Xna.Framework.Graphics;
using Microsoft.Xna.Framework.Input;
using Microsoft.Xna.Framework.Media;
using Microsoft.Xna.Framework.Net;
using Microsoft.Xna.Framework.Storage;

namespace SkyBox
{
 public class Game1 : Microsoft.Xna.Framework.Game
 {
 GraphicsDeviceManager graphics;
 SpriteBatch spriteBatch;

 CameraLib.Camera camera;

 Model skybox;
 SpriteFont fnt;
 TextureCube texture;
 Effect effect;

 Matrix modRow=Matrix.Identity;

 public Game1()
 {
 graphics = new GraphicsDeviceManager(this);
 Content.RootDirectory = "Content";
 }

 protected override void Initialize()
 {
 camera = new CameraLib.Camera(MathHelper.PiOver4, GraphicsDevice.Viewport.AspectRatio, 1, 1000,
 new Vector3(0, 0, 50), Vector3.Forward, Vector3.Up);

 base.Initialize();
 }

 protected override void LoadContent()
 {
 // Create a new SpriteBatch, which can be used to draw textures.
 spriteBatch = new SpriteBatch(GraphicsDevice);

 skybox = Content.Load<Model>("skybox");
 fnt = Content.Load<SpriteFont>("fnt");
 texture = Content.Load<TextureCube>("SkyboxTex");
 effect = Content.Load<Effect>("effect");
 }

 protected override void Update(GameTime gameTime)
 {
 KeyboardState ks = Keyboard.GetState();

 if (ks.IsKeyDown(Keys.Escape))
 {
 Exit();
 }

 if (ks.IsKeyDown(Keys.NumPad4))
 {
 modRow *= Matrix.CreateRotationY(0.1f);
 }
 if (ks.IsKeyDown(Keys.NumPad6))
 {
 modRow *= Matrix.CreateRotationY(-0.1f);
 }
 if (ks.IsKeyDown(Keys.NumPad8))
 {
 modRow *= Matrix.CreateRotationZ(0.1f);
 }
 if (ks.IsKeyDown(Keys.NumPad5))
 {
 modRow *= Matrix.CreateRotationZ(-0.1f);
 }
 if (ks.IsKeyDown(Keys.NumPad7))
 {
 modRow *= Matrix.CreateRotationX(0.1f);
 }
 if (ks.IsKeyDown(Keys.NumPad9))
 {
 modRow *= Matrix.CreateRotationX(-0.1f);
 }

 camera.UpdateMatrix();

 base.Update(gameTime);
 }

 protected override void Draw(GameTime gameTime)
 {
 graphics.GraphicsDevice.Clear(Color.CornflowerBlue);

 effect.Parameters["World"].SetValue(modRow*Matrix.CreateScale(30f));
 effect.Parameters["View"].SetValue(camera.View);
 effect.Parameters["Projection"].SetValue(camera.Projection);

 effect.Parameters["textu"].SetValue(texture);
 effect.Parameters["eyePosition"].SetValue(camera.mposi);

 foreach(ModelMesh mesh in skybox.Meshes)
 {
 foreach (ModelMeshPart part in mesh.MeshParts)
 {
 part.Effect = effect;
 }
 mesh.Draw();
 }

 spriteBatch.Begin(SpriteBlendMode.AlphaBlend);

 spriteBatch.DrawString(fnt, "Position:" + camera.mposi.ToString() + "\n" +
 "Target:" + camera.mtarget.ToString() + "\n" +
 "up:" + camera.mup.ToString(), Vector2.Zero, Color.White);

 spriteBatch.End();

 base.Draw(gameTime);
 }
 }
}

 

 

好了，看下效果：

 

其实要实现天空效果也不只有一种方法，还可以通过一个"房顶"完成。

通过上面的模型也能实现天空效果。