XNA系列—3d模型的导入

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 My3DGame
{
    public class Game1 : Microsoft.Xna.Framework.Game
    {
        GraphicsDeviceManager graphics;
        SpriteBatch spriteBatch;

        Model terrain;   //地形的模型
        Vector3 terrainPosition; //地形的世界坐标位置

        Matrix cameraViewMatrix;   //照相机视图矩阵
        Matrix cameraProjectionMatrix;  //照相机投影矩阵

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


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

        protected override void LoadContent()
        {
            spriteBatch = new SpriteBatch(GraphicsDevice);
            terrain = Content.Load<Model>("Models\\terrain");
            terrainPosition = Vector3.Zero;

           
            //初始化摄像机的视图矩阵  参数： 摄像机位置，摄像机目标位置，看的方向
            cameraViewMatrix = Matrix.CreateLookAt(
                 new Vector3(0f, 60f, 160f),
                 new Vector3(0f, 50f, 0f),
                 Vector3.Up);
            //初始化摄像机的投影矩阵 参数：摄像机看的范围、屏幕的比例、照相机看的最近的距离、照相机看的最远的距离
            cameraProjectionMatrix = Matrix.CreatePerspectiveFieldOfView(
                MathHelper.PiOver4,
                graphics.GraphicsDevice.Viewport.AspectRatio,
                1f,
                10000f);

        }

        protected override void UnloadContent()
        {
        }

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


        protected override void Draw(GameTime gameTime)
        {
            GraphicsDevice.Clear(Color.CornflowerBlue);
            foreach (ModelMesh mesh in terrain.Meshes)
            {
                foreach (BasicEffect effect in mesh.Effects)
                {
                    effect.EnableDefaultLighting();
                    effect.PreferPerPixelLighting = true;

                    effect.World = Matrix.CreateTranslation(terrainPosition);  //将世界坐标转化成矩阵坐标
                    effect.View = cameraViewMatrix;
                    effect.Projection = cameraProjectionMatrix;
                }
                mesh.Draw();
            }
            base.Draw(gameTime);
        }
    }
}