游戏人生Silverlight：星际竞技场-51CTO.COM

介绍

使用 Silverlight 2.0(c#, Farseer Physics Engine) 开发一个射击游戏：星际竞技场

玩法

W 或者 ↑ = 前进；S 或者 ↓ = 后退：A 或者 ← = 左转；D 或者 → = 右转；J 或者 Ctrl = 开火

思路

1、使用一个开源的 Silverlight 物理引擎：Farseer Physics Engine

2、将 Farseer Physics Engine 中的物理运算器 PhysicsSimulator 放到一个全局变量中，对 Body 和 Geom 做即时运算，

3、写个 IPhysicsControl 接口，用于描述物理对象的各个属性，需要运动和碰撞的对象，要实现该接口抽象出来的各个属性

4、写个抽象类（Sprite），在其内封装好物理引擎。各种类型的物理对象的模拟器，都需要重写该抽象类的两个方法GetForce()和GetTorque()即可，其分别要返回对象在当前时刻所受到的牵引力和力矩

5、写个 IFire 接口，所有可开火的对象都要实现该接口

6、写个控件 PhysicsBox，用于包装 IPhysicsControl，从而将模拟器计算出的运动和碰撞结果呈现到界面上

关键代码Sprite.cs（Sprite 模拟器的基类）

using System;  
using System.Net;  
using System.Windows;  
using System.Windows.Controls;  
using System.Windows.Documents;  
using System.Windows.Ink;  
using System.Windows.Input;  
using System.Windows.Media;  
using System.Windows.Media.Animation;  
using System.Windows.Shapes;  
 
using FarseerGames.FarseerPhysics;  
using FarseerGames.FarseerPhysics.Mathematics;  
using FarseerGames.FarseerPhysics.Dynamics;  
using FarseerGames.FarseerPhysics.Collisions;  
 
namespace YYArena.Core  
{  
    /**//// <summary> 
    /// Sprite 基类  
    /// </summary> 
    public abstract class Sprite  
    {  
        private PhysicsSimulator _physicsSimulator;  
 
        protected PhysicsBox playerBox;  
        protected Geom playerGeometry;  
 
        /**//// <summary> 
        /// 构造函数  
        /// </summary> 
        /// <param name="physicsSimulator">PhysicsSimulator</param> 
        /// <param name="physicsControl">IPhysicsControl</param> 
        /// <param name="position">初始位置</param> 
        /// <param name="angle">初始转角</param> 
        /// <param name="originalVelocity">初始速度</param> 
        public Sprite(PhysicsSimulator physicsSimulator,  
            IPhysicsControl physicsControl, Vector2 position, float angle, float originalVelocity)  
        {  
            _physicsSimulator = physicsSimulator;  
 
            playerBox = new PhysicsBox(physicsControl);  
            playerBox.Body.Position = position;  
            playerBox.Body.Rotation = (float)Helper.Angle2Radian(angle);  
            playerBox.Body.LinearVelocity = Helper.Convert2Vector(originalVelocity, (float)Helper.Angle2Radian(angle));  
 
            // Body 和 Geom 的 Tag 保存为 Sprite，方便引用  
            playerBox.Body.Tag = this;  
            playerBox.Geom.Tag = this;  
 
            playerBox.Update();  
        }  
 
        /**//// <summary> 
        /// 即时计算力和力矩  
        /// </summary> 
        void CompositionTarget_Rendering(object sender, EventArgs e)  
        {  
            if (Enabled)  
            {  
                var force = GetForce();  
                var torque = GetTorque();  
 
                playerBox.Body.ApplyForce(force);  
                playerBox.Body.ApplyTorque(torque);  
 
                playerBox.Update();  
            }  
        }  
 
        /**//// <summary> 
        /// 返回 Sprite 当前受的力  
        /// </summary> 
        protected abstract Vector2 GetForce();  
        /**//// <summary> 
        /// 返回 Sprite 当前受的力矩  
        /// </summary> 
        protected abstract float GetTorque();  
 
        public PhysicsBox PhysicsBox  
        {  
            get { return playerBox; }  
        }  
 
        private bool _enabled = false;  
        /**//// <summary> 
        /// 是否启用此 Sprite  
        /// </summary> 
        public bool Enabled  
        {  
            get { return _enabled; }  
            set  
            {   
                _enabled = value;  
 
                if (value)  
                {  
                    CompositionTarget.Rendering += new EventHandler(CompositionTarget_Rendering);  
 
                    _physicsSimulator.Add(playerBox.Body);  
                    _physicsSimulator.Add(playerBox.Geom);  
                }  
                else  
                {  
                    CompositionTarget.Rendering -= new EventHandler(CompositionTarget_Rendering);  
 
                    GC.SuppressFinalize(this);  
                    _physicsSimulator.Remove(playerBox.Body);  
                    _physicsSimulator.Remove(playerBox.Geom);  
                }  
            }  
        }  
    }  
}

#p#

PlayerSprite.cs（玩家 Sprite 模拟器）

using System;  
using System.Net;  
using System.Windows;  
using System.Windows.Controls;  
using System.Windows.Documents;  
using System.Windows.Ink;  
using System.Windows.Input;  
using System.Windows.Media;  
using System.Windows.Media.Animation;  
using System.Windows.Shapes;  
 
using System.Collections.Generic;  
using FarseerGames.FarseerPhysics.Mathematics;  
using FarseerGames.FarseerPhysics;  
using FarseerGames.FarseerPhysics.Collisions;  
 
namespace YYArena.Core  
{  
    /**//// <summary> 
    /// 玩家 Sprite  
    /// </summary> 
    public class PlayerSprite : Sprite, IFire  
    {  
        private List<Key> _upKeys { get; set; }  
        private List<Key> _downKeys { get; set; }  
        private List<Key> _leftKeys { get; set; }  
        private List<Key> _rightKeys { get; set; }  
        private List<Key> _fireKeys { get; set; }  
 
        private KeyboardHandler _keyHandler;  
        private IPhysicsControl _physicsControl;  
 
        /**//// <summary> 
        /// 构造函数  
        /// </summary> 
        /// <param name="physicsSimulator">PhysicsSimulator</param> 
        /// <param name="physicsControl">IPhysicsControl</param> 
        /// <param name="position">初始位置</param> 
        /// <param name="angle">初始转角</param> 
        /// <param name="originalVelocity">初始速度</param> 
        /// <param name="keyboardHandler">KeyboardHandler</param> 
        /// <param name="up">操作玩家向前移动的按键集合</param> 
        /// <param name="down">操作玩家向后移动的按键集合</param> 
        /// <param name="left">操作玩家向左转动的按键集合</param> 
        /// <param name="right">操作玩家向右转动的按键集合</param> 
        /// <param name="fire">操作玩家开火的按键集合</param> 
        public PlayerSprite(PhysicsSimulator physicsSimulator,  
            IPhysicsControl physicsControl, Vector2 position, float angle, float originalVelocity,  
            KeyboardHandler keyboardHandler,  
            List<Key> up, List<Key> down, List<Key> left, List<Key> right, List<Key> fire)  
            : base(physicsSimulator, physicsControl, position, angle, originalVelocity)  
        {  
            PrevFireDateTime = DateTime.MinValue;  
            MinFireInterval = 500d;  
 
            _upKeys = up;  
            _downKeys = down;  
            _leftKeys = left;  
            _rightKeys = right;  
            _fireKeys = fire;  
 
            _keyHandler = keyboardHandler;  
            _physicsControl = physicsControl;  
 
            CompositionTarget.Rendering += new EventHandler(CompositionTarget_Rendering);  
        }  
 
        void CompositionTarget_Rendering(object sender, EventArgs e)  
        {  
            if (Enabled)  
            {  
                // 如果按了开火键，是否可开火  
                if (_keyHandler.AnyKeyPressed(_fireKeys) && (DateTime.Now - PrevFireDateTime).TotalMilliseconds > MinFireInterval)  
                {  
                    PrevFireDateTime = DateTime.Now;  
                    if (Fire != null)  
                        Fire(this, EventArgs.Empty);  
                }  
            }  
        }  
 
        public DateTime PrevFireDateTime { get; set; }  
 
        public double MinFireInterval { get; set; }  
 
        public event EventHandler<EventArgs> Fire;  
 
        protected override Vector2 GetForce()  
        {  
            Vector2 force = Vector2.Zero;  
 
            if (_keyHandler.AnyKeyPressed(_upKeys))  
                force += Helper.Convert2Vector(_physicsControl.ForceAmount, playerBox.Body.Rotation);  
            if (_keyHandler.AnyKeyPressed(_downKeys))  
                force += Helper.Convert2Vector(_physicsControl.ForceAmount, playerBox.Body.Rotation - Helper.Angle2Radian(180));  
 
            // 最大线性速度限制  
            if (playerBox.Body.LinearVelocity.Length() > _physicsControl.MaxLinearVelocity)  
                force = Vector2.Zero;  
 
            return force;  
        }  
 
        protected override float GetTorque()  
        {  
            float torque = 0;  
 
            if (_keyHandler.AnyKeyPressed(_leftKeys))  
                torque -= _physicsControl.TorqueAmount;  
            if (_keyHandler.AnyKeyPressed(_rightKeys))  
                torque += _physicsControl.TorqueAmount;  
 
            // 用于修正 RotationalDragCoefficient （在没有任何 Torque 的情况下，如果转速小于 1.3 则设其为 0）  
            // 如果不做此修正的话，转速小于 1.3 后还会转好长时间  
            if (!_keyHandler.AnyKeyPressed(_leftKeys) && !_keyHandler.AnyKeyPressed(_rightKeys) && Math.Abs(playerBox.Body.AngularVelocity) < 1.3)  
                playerBox.Body.AngularVelocity = 0;  
 
            // 最大转速限制  
            if (Math.Abs(playerBox.Body.AngularVelocity) > _physicsControl.MaxAngularVelocity)  
                torque = 0;  
 
            return torque;  
        }  
    }  
}

#p#

AISprite.cs（敌军 Sprite 模拟器）

using System;  
using System.Net;  
using System.Windows;  
using System.Windows.Controls;  
using System.Windows.Documents;  
using System.Windows.Ink;  
using System.Windows.Input;  
using System.Windows.Media;  
using System.Windows.Media.Animation;  
using System.Windows.Shapes;  
 
using System.Collections.Generic;  
using FarseerGames.FarseerPhysics.Mathematics;  
 
using FarseerGames.FarseerPhysics;  
using FarseerGames.FarseerPhysics.Collisions;  
using FarseerGames.FarseerPhysics.Dynamics;  
 
namespace YYArena.Core  
{  
    /**//// <summary> 
    /// 敌军 Sprite  
    /// </summary> 
    public class AISprite : Sprite, IFire  
    {  
        private Sprite _attackTarget;  
        private int _aiLevel;  
        private IPhysicsControl _physicsControl;  
 
        /**//// <summary> 
        /// 构造函数  
        /// </summary> 
        /// <param name="physicsSimulator">PhysicsSimulator</param> 
        /// <param name="physicsControl">IPhysicsControl</param> 
        /// <param name="position">初始位置</param> 
        /// <param name="angle">初始转角</param> 
        /// <param name="originalVelocity">初始速度</param> 
        /// <param name="attackTarget">攻击目标</param> 
        /// <param name="aiLevel">ai等级</param> 
        public AISprite(PhysicsSimulator physicsSimulator,  
            IPhysicsControl physicsControl, Vector2 position, float angle, float originalVelocity, Sprite attackTarget, int aiLevel)  
            : base(physicsSimulator, physicsControl, position, angle, originalVelocity)  
        {  
            // 上次开火时间  
            PrevFireDateTime = DateTime.Now.AddSeconds(3);  
            // 最小开火间隔  
            MinFireInterval = 3000d;  
 
            _attackTarget = attackTarget;  
            _aiLevel = aiLevel;  
            _physicsControl = physicsControl;  
 
            InitAI();  
 
            CompositionTarget.Rendering += new EventHandler(CompositionTarget_Rendering);  
        }  
 
        private void InitAI()  
        {  
            // 根据 ai 等级设置最小开火间隔  
            double fireCoefficient = 1 + 30 / _aiLevel;  
            MinFireInterval = Helper.GenerateRandom((int)MinFireInterval, (int)(fireCoefficient * MinFireInterval));  
        }  
 
        void CompositionTarget_Rendering(object sender, EventArgs e)  
        {  
            if (Enabled && AttackTarget.Enabled)  
            {  
                // 是否开火  
                if ((DateTime.Now - PrevFireDateTime).TotalMilliseconds > MinFireInterval)  
                {  
                    PrevFireDateTime = DateTime.Now;  
 
                    if (Fire != null)  
                        Fire(this, EventArgs.Empty);  
                }  
            }  
        }  
 
        public DateTime PrevFireDateTime { get; set; }  
 
        public double MinFireInterval { get; set; }  
 
        public event EventHandler<EventArgs> Fire;  
 
 
        public Sprite AttackTarget  
        {  
            get { return _attackTarget; }  
            set { _attackTarget = value; }  
        }  
 
        protected override Vector2 GetForce()  
        {  
            Vector2 force = Vector2.Zero;  
 
            if (!_attackTarget.Enabled)  
                return force;  
 
            force += Helper.Convert2Vector(_physicsControl.ForceAmount, playerBox.Body.Rotation);  
 
            // 根据 ai 等级做最大线性速度限制  
            if (playerBox.Body.LinearVelocity.Length() > _physicsControl.MaxLinearVelocity * Helper.GenerateRandom(50, 200) / 1000)  
                force = Vector2.Zero;  
 
            return force;  
        }  
 
        protected override float GetTorque()  
        {  
            float torque = 0f;  
 
            if (!_attackTarget.Enabled)  
                return torque;  
 
            // 按某个方向旋转，原则是以最小的旋转角度对准目标  
            Vector2 relativePosition = _attackTarget.PhysicsBox.Body.Position - playerBox.Body.Position;  
            double targetRotation = Helper.Convert2Rotation(relativePosition);  
            double currentRotation = playerBox.Body.Rotation;  
            double relativeAngle = Helper.Radian2Angle(targetRotation - currentRotation);  
            if (relativeAngle < 0)  
                relativeAngle += 360;  
 
            if (relativeAngle > 1)  
            {  
                if (relativeAngle < 180 && relativeAngle > 0)  
                    torque += _physicsControl.TorqueAmount;  
                else if (relativeAngle > 180 && relativeAngle < 360)  
                    torque -= _physicsControl.TorqueAmount;  
            }  
            else  
            {  
                playerBox.Body.AngularVelocity = 0;  
            }  
 
 
            // 最大转速限制  
            if (Math.Abs(playerBox.Body.AngularVelocity) > _physicsControl.MaxAngularVelocity)  
                torque = 0;  
             
            return torque;  
        }  
    }  
}

[源码下载]

原文链接：http://www.cnblogs.com/webabcd/archive/2009/06/22/1508042.html