GenMipmapsTest.cs

using Microsoft.Xna.Framework;
using Microsoft.Xna.Framework.Graphics;

namespace ShaderTest
{
    class ShaderTestGame : Game
    {
        GraphicsDeviceManager graphics;

        RenderTarget2D renderTarget;
        SpriteBatch spriteBatch;
        SamplerState lowDetail;
        Texture2D surge;

        public static void Main(string[] args)
        {
            using (ShaderTestGame game = new ShaderTestGame())
            {
                game.Run();
            }
        }

        public ShaderTestGame()
        {
            graphics = new GraphicsDeviceManager(this);
            graphics.PreferredBackBufferWidth = 1280;
            graphics.PreferredBackBufferHeight = 720;
            graphics.PreferMultiSampling = false;
            Content.RootDirectory = "Content";

            Window.AllowUserResizing = false;
            IsMouseVisible = true;
        }

        protected override void LoadContent()
        {
            base.LoadContent();
            spriteBatch = new SpriteBatch(GraphicsDevice);
            renderTarget = new RenderTarget2D(GraphicsDevice, 200, 200, true, SurfaceFormat.Color, DepthFormat.None);
            surge = Content.Load<Texture2D>("surge");
            lowDetail = SamplerState.PointClamp;
            lowDetail.MaxMipLevel = 2;
        }

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

        protected override void Update(GameTime gameTime)
        {
            base.Update(gameTime);
        }

        protected override void Draw(GameTime gameTime)
        {
            GraphicsDevice.SetRenderTarget(renderTarget);
            GraphicsDevice.Clear(Color.CornflowerBlue);
            spriteBatch.Begin();
            spriteBatch.Draw(surge, Vector2.Zero, Color.White);
            spriteBatch.End();

            GraphicsDevice.SetRenderTarget(null);

            GraphicsDevice.Clear(Color.CornflowerBlue);
            spriteBatch.Begin(SpriteSortMode.Deferred, BlendState.AlphaBlend);
            spriteBatch.Draw(renderTarget, Vector2.Zero, Color.White);
            spriteBatch.End();

            spriteBatch.Begin(SpriteSortMode.Deferred, BlendState.AlphaBlend, lowDetail, DepthStencilState.None, RasterizerState.CullNone);
            spriteBatch.Draw(renderTarget, new Vector2(0, 200), Color.White);
            spriteBatch.End();

            base.Draw(gameTime);
        }
    }
}