XNA 4.0 - Alpha和多个纹理...搞砸了

Question

我想做出某种滑动菜单...在一个圆圈图像将滑落或向上，因为用户将触摸图标并滑动它们（如现代手机或赌场机器的水果等...）

我有一个透明的圆圈，并让我们说三个图标......我如何融合他们在这种方式？

项目：

http://i52.tinypic.com/rcn67s.jpg

问题：

http://i52.tinypic.com/i77nrk.jpg

我可以让他们得到由spriteBatch一个拉一个与订单，但如何以这种方式融入其中？

我很抱歉，我能感觉到它的东西，可能是容易的，但我坚持..

谢谢！

Answer 1

我做到了......下面是如何：

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; 

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

     Texture2D star, cloud, shape; 
     AlphaTestEffect alphaTestEffect; 
     DepthStencilState stencilAlways; 
     DepthStencilState stencilKeep; 
     RenderTarget2D rt; 

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

      graphics.PreferredDepthStencilFormat = DepthFormat.Depth24Stencil8; 

      graphics.PreferredBackBufferWidth = 800; 
      graphics.PreferredBackBufferHeight = 600; 

      IsMouseVisible = true; 
     } 

     protected override void Initialize() 
     { 
      base.Initialize(); 
     } 

     Texture2D grass; 

     protected override void LoadContent() 
     { 
      // Create a new SpriteBatch, which can be used to draw textures. 
      spriteBatch = new SpriteBatch(GraphicsDevice); 
      star = Content.Load<Texture2D>("star1"); 
      cloud = Content.Load<Texture2D>("cloud1"); 
      shape = Content.Load<Texture2D>("shape"); 
      back = Content.Load<Texture2D>("back"); 
      grass = Content.Load<Texture2D>("grass1"); 

      Matrix projection = Matrix.CreateOrthographicOffCenter(0, shape.Width, shape.Height, 0, 0, 1); 
      Matrix halfPixelOffset = Matrix.CreateTranslation(-0.5f, -0.5f, 0); 

      alphaTestEffect = new AlphaTestEffect(GraphicsDevice); 
      alphaTestEffect.VertexColorEnabled = true; 
      alphaTestEffect.DiffuseColor = Color.White.ToVector3(); 
      alphaTestEffect.AlphaFunction = CompareFunction.Equal; 
      alphaTestEffect.ReferenceAlpha = 0; 
      alphaTestEffect.World = Matrix.Identity; 
      alphaTestEffect.View = Matrix.Identity; 
      alphaTestEffect.Projection = halfPixelOffset * projection; 

      // set up stencil state to always replace stencil buffer with 1 
      stencilAlways = new DepthStencilState(); 
      stencilAlways.StencilEnable = true; 
      stencilAlways.StencilFunction = CompareFunction.Always; 
      stencilAlways.StencilPass = StencilOperation.Replace; 
      stencilAlways.ReferenceStencil = 1; 
      stencilAlways.DepthBufferEnable = false; 

      // set up stencil state to pass if the stencil value is 1 
      stencilKeep = new DepthStencilState(); 
      stencilKeep.StencilEnable = true; 
      stencilKeep.StencilFunction = CompareFunction.Equal; 
      stencilKeep.StencilPass = StencilOperation.Keep; 
      stencilKeep.ReferenceStencil = 1; 
      stencilKeep.DepthBufferEnable = false; 

      rt = new RenderTarget2D(GraphicsDevice, shape.Width, shape.Height, 
            false, SurfaceFormat.Color, DepthFormat.Depth24Stencil8, 
            0, RenderTargetUsage.DiscardContents); 
     } 

     protected override void UnloadContent() 
     { 

     } 

     protected override void Update(GameTime gameTime) 
     { 
      // Allows the game to exit 
      if (Keyboard.GetState().IsKeyDown(Keys.Escape)) 
       this.Exit(); 

      // TODO: Add your update logic here 

      base.Update(gameTime); 
     } 

     float angle = 0f; 
     private Texture2D back; 
     Vector2 pos = new Vector2(400, 300); 
     float cloudscale = 0.25f; 

     protected override void Draw(GameTime gameTime) 
     { 

      // set up rendering to the active render target 
      GraphicsDevice.SetRenderTarget(rt); 

      // clear the render target to opaque black, 
      // and initialize the stencil buffer with all zeroes 
      GraphicsDevice.Clear(ClearOptions.Target | ClearOptions.Stencil, 
           new Color(0, 0, 0, 1), 0, 0); 

      spriteBatch.Begin(SpriteSortMode.Immediate, BlendState.Opaque, 
         null, stencilAlways, null, alphaTestEffect); 

      spriteBatch.Draw(shape, Vector2.Zero, null, Color.White, 0f, 
          Vector2.Zero, 1f, SpriteEffects.None, 0f); 

      spriteBatch.End(); 

      spriteBatch.Begin(SpriteSortMode.Immediate, BlendState.AlphaBlend, 
        null, stencilKeep, null, null); 

      //for (int i = 0; i < Math.Ceiling(800/(cloud.Width * cloudscale)); i++) 
      // for (int j = 0; j < Math.Ceiling(600/(cloud.Height * cloudscale)); j++) 
      //  spriteBatch.Draw(cloud, Vector2.Zero + new Vector2(i * cloud.Width * cloudscale, j * cloud.Height * cloudscale), null, Color.White, 0f, 
      //   Vector2.Zero, cloudscale, SpriteEffects.None, 0f); 

      spriteBatch.Draw(grass, new Vector2(rt.Width/2, rt.Height/2) + new Vector2(0f, -100f), null, Color.White, 0f, 
     new Vector2(grass.Width/2, grass.Height/2), .85f, SpriteEffects.None, 0f); 

      spriteBatch.Draw(cloud, new Vector2(rt.Width/2, rt.Height/2), null, Color.White, 0f, 
        new Vector2(cloud.Width/2, cloud.Height/2), 1f, SpriteEffects.None, 0f); 

      spriteBatch.Draw(star, new Vector2(rt.Width/2, rt.Height/2) + new Vector2(0f, 100f), null, Color.White, 0f, 
     new Vector2(star.Width/2, star.Height/2), .85f, SpriteEffects.None, 0f); 

      spriteBatch.End(); 

      GraphicsDevice.SetRenderTarget(null); 

      spriteBatch.Begin(); 

      spriteBatch.Draw(back, Vector2.Zero, null, Color.White, 0f, Vector2.Zero, 1f, SpriteEffects.None, 0f); 

      spriteBatch.Draw(rt, pos + new Vector2(50f * (float)Math.Cos(MathHelper.ToRadians(angle)), 50f * (float)Math.Sin(MathHelper.ToRadians(angle))), null, Color.White, 0f, new Vector2(rt.Width/2, rt.Height/2), 1f, SpriteEffects.None, 0f); 

      spriteBatch.End(); 

      // TODO: Add your drawing code here 

      angle +=0.5f; 

      base.Draw(gameTime); 
     } 
    } 
} 

Answer 2

难道你不能只是让这个圆圈变大一些，这样它下面就不会显示任何东西，并将它放在最上面？