用XInput库使用xbox360手柄

前言

XInput库是微软开发的库，功能是让xbox360类型的手柄能在Windows PC平台使用。它被附带在DXSDK_Jun10开发包中（我写的框架基于这个版本），链接和实际使用都特别简单。这篇文章应该可以让你更快的使用上XInput。

环境配置

包含文件和DX11的配置一样，头文件都在同一个目录下，如果之前配置了DX库，就不需要额外做什么。只需要链接上附加依赖项 XInput.lib。
在代码中也只需要包含头文件XInput.h。

最后接口

class Input_imp;//输入的单例类
class DLL_API GamePad
{   friend class Input_imp;
public://按键状态bool KeyUp(int pad);bool KeyDown(int pad);bool KeyState(int pad);//LT、RT的按下程度：[0,1]float ForceLT();float ForceRT();//LS、RS的位置偏移程度：[0,1]Vector2 GetLS();Vector2 GetRS();//LS、RS离原地的距离：[0,1]float ForceLS();float ForceRS();//设置振动，左右马达的各自强度：[0,1]void SetVibration(Vector2 lr);
private:UINT32 _id;//手柄编号 0-3Input_imp* _input;
};

上面的值均规范化到0到1的范围。
其中LT、RT需要返回按下的程度，在XInput库中名字叫Trigger。LS、RS代表左右两个摇杆，在Xinput中叫Thumb。
其它的按钮均只有按下和非按下状态，所以使用KeyUp、KeyDown、KeyState来返回它们的状态。KeyUp代表上一帧按下，这一帧没有按下。KeyDown代表上一帧没按下，但此帧按下。KeyState返回当前是否按下。
单个状态的按钮枚举值如下：

struct DLL_API PadCode
{
public:enum NAME{UP          = 0x00000001,DOWN        = 0x00000002,LEFT        = 0x00000004,RIGHT       = 0x00000008,START       = 0x00000010,BACK        = 0x00000020,LS          = 0x00000040,RS          = 0x00000080,LB          = 0x0100,RB          = 0x0200,A           = 0x1000,B           = 0x2000,X           = 0x4000,Y           = 0x8000};
};

通过名字，读者就应该知道代表什么含义了。如果要检测组合键应该使用第二种方式：

gamepad->KeyDown(UP | LEFT);//错误
gamepad->KeyDown(A) && gamepad->KeyDown(B);//正确

具体实现

由于暂时支持最多4个手柄，Input_imp类需要存储4个GamePad类对象，4个当前按键状态，4个上一帧按键状态。用户调用GetGamePad(N)时返回第N个手柄，如果手柄不存在，就返回NULL。

XINPUT_STATE _xinputState[MAX_CONTROLLERS];//当前状态
XINPUT_STATE _xinputStatePre[MAX_CONTROLLERS];//上一帧状态
GamePad _gamePad[MAX_CONTROLLERS];//手柄接口
bool _gamePadConnected[MAX_CONTROLLERS];//手柄是否连接

XINPUT_STATE结构体包含了手柄按键的所有状态，如下

typedef struct _XINPUT_GAMEPAD
{WORD                                wButtons; //单个状态按钮们的组合值BYTE                                bLeftTrigger;//LT [0,255]BYTE                                bRightTrigger;//RT [0,255]SHORT                               sThumbLX;//LS 的X轴位移 [-32768,32767]SHORT                               sThumbLY;//LS 的Y轴位移 [-32768,32767]SHORT                               sThumbRX;//RS 的X轴位移 [-32768,32767]SHORT                               sThumbRY;//RS 的Y轴位移 [-32768,32767]
} XINPUT_GAMEPAD, *PXINPUT_GAMEPAD;typedef struct _XINPUT_STATE
{DWORD                               dwPacketNumber;XINPUT_GAMEPAD                      Gamepad;
} XINPUT_STATE, *PXINPUT_STATE;

我们就在每帧调用下面的函数，获取到手柄的按钮状态：

void Input_imp::_xinput_run()
{DWORD dwResult;for (DWORD i = 0; i < MAX_CONTROLLERS; i++){_xinputStatePre[i] = _xinputState[i];//上一帧状态ZeroMemory(&_xinputState[i], sizeof(XINPUT_STATE));// Simply get the state of the controller from XInput.dwResult = XInputGetState(i, &_xinputState[i]);if (dwResult == ERROR_SUCCESS){//获取成功// Controller is connected _gamePadConnected[i] = true;}else{//获取失败，手柄不存在// Controller is not connected _gamePadConnected[i] = false;}}}

然后手柄状态被存储到了_xinputState中，接下来只需要GampPad类访问即可，但其中需要做一些处理。第一是将数值规范化到[0,1]，其次是过小的值需要归0。所有成员函数的实现都列出来了，由于并不复杂，我就不多说了，许多直接copy自文档，并做了一些改动（文档的并不能直接使用）。

GamePad* Input_imp::GetGamePad(UINT32 id)
{if (_gamePadConnected[id])return &_gamePad[id];elsereturn NULL;
}bool GamePad::KeyUp(int pad)
{return !(_input->_xinputState[_id].Gamepad.wButtons & pad) && (_input->_xinputStatePre[_id].Gamepad.wButtons & pad);
}bool GamePad::KeyDown(int pad)
{return (_input->_xinputState[_id].Gamepad.wButtons & pad) &&!(_input->_xinputStatePre[_id].Gamepad.wButtons & pad);
}bool GamePad::KeyState(int pad)
{return _input->_xinputState[_id].Gamepad.wButtons & pad;
}float GamePad::ForceLT()
{if (_input->_xinputState[_id].Gamepad.bLeftTrigger < XINPUT_GAMEPAD_TRIGGER_THRESHOLD)return 0;return _input->_xinputState[_id].Gamepad.bLeftTrigger / 255.0f;
}float GamePad::ForceRT()
{BYTE ret = _input->_xinputState[_id].Gamepad.bRightTrigger;if (ret < XINPUT_GAMEPAD_TRIGGER_THRESHOLD)return 0;return ret / 255.0f;
}Vector2 GamePad::GetLS()
{float LX = _input->_xinputState[_id].Gamepad.sThumbLX;float LY = -_input->_xinputState[_id].Gamepad.sThumbLY;if (abs(LX) < XINPUT_GAMEPAD_LEFT_THUMB_DEADZONE)LX = 0;if (abs(LY) < XINPUT_GAMEPAD_LEFT_THUMB_DEADZONE)LY = 0;if (LX == 0 && LY == 0)return Vector2();//determine how far the controller is pushedfloat magnitude = sqrt(LX*LX + LY*LY);//determine the direction the controller is pushedfloat normalizedLX = LX / magnitude;float normalizedLY = LY / magnitude;return Vector2(normalizedLX, normalizedLY);
}Vector2 GamePad::GetRS()
{float RX = _input->_xinputState[_id].Gamepad.sThumbRX;float RY = -_input->_xinputState[_id].Gamepad.sThumbRY;if (abs(RX) < XINPUT_GAMEPAD_RIGHT_THUMB_DEADZONE)RX = 0;if (abs(RY) < XINPUT_GAMEPAD_RIGHT_THUMB_DEADZONE)RY = 0; if (RX == 0 && RY == 0)return Vector2();//determine how far the controller is pushedfloat magnitude = sqrt(RX*RX + RY*RY);//determine the direction the controller is pushedfloat normalizedRX = RX / magnitude;float normalizedRY = RY / magnitude;return Vector2(normalizedRX, normalizedRY);
}float GamePad::ForceLS()
{//copy 自DirectX文档float LX = _input->_xinputState[_id].Gamepad.sThumbLX;float LY = _input->_xinputState[_id].Gamepad.sThumbLY;//determine how far the controller is pushedfloat magnitude = sqrt(LX*LX + LY*LY);//determine the direction the controller is pushedfloat normalizedLX = LX / magnitude;float normalizedLY = LY / magnitude;float normalizedMagnitude = 0;//check if the controller is outside a circular dead zoneif (magnitude > XINPUT_GAMEPAD_LEFT_THUMB_DEADZONE){//clip the magnitude at its expected maximum valueif (magnitude > 32767) magnitude = 32767;//adjust magnitude relative to the end of the dead zonemagnitude -= XINPUT_GAMEPAD_LEFT_THUMB_DEADZONE;//optionally normalize the magnitude with respect to its expected range//giving a magnitude value of 0.0 to 1.0normalizedMagnitude = magnitude / (32767 - XINPUT_GAMEPAD_LEFT_THUMB_DEADZONE);}else //if the controller is in the deadzone zero out the magnitude{magnitude = 0.0f;normalizedMagnitude = 0.0f;}return normalizedMagnitude;
}float GamePad::ForceRS()
{//copy 自DirectX文档float RX = _input->_xinputState[_id].Gamepad.sThumbLX;float RY = _input->_xinputState[_id].Gamepad.sThumbLY;//determine how far the controller is pushedfloat magnitude = sqrt(RX*RX + RY*RY);//determine the direction the controller is pushedfloat normalizedRX = RX / magnitude;float normalizedRY = RY / magnitude;float normalizedMagnitude = 0;//check if the controller is outside a circular dead zoneif (magnitude > XINPUT_GAMEPAD_RIGHT_THUMB_DEADZONE){//clip the magnitude at its expected maximum valueif (magnitude > 32767) magnitude = 32767;//adjust magnitude relative to the end of the dead zonemagnitude -= XINPUT_GAMEPAD_RIGHT_THUMB_DEADZONE;//optionally normalize the magnitude with respect to its expected range//giving a magnitude value of 0.0 to 1.0normalizedMagnitude = magnitude / (32767 - XINPUT_GAMEPAD_RIGHT_THUMB_DEADZONE);}else //if the controller is in the deadzone zero out the magnitude{magnitude = 0.0f;normalizedMagnitude = 0.0f;}return normalizedMagnitude;
}void GamePad::SetVibration(Vector2 lr)
{XINPUT_VIBRATION vibration;ZeroMemory(&vibration, sizeof(XINPUT_VIBRATION));vibration.wLeftMotorSpeed = lr.a * 65535; // use any value between 0-65535 herevibration.wRightMotorSpeed = lr.b * 65535; // use any value between 0-65535 hereXInputSetState(_id, &vibration);}

测试效果

下图为通过手柄操作后的结果

实际的源码请参考
https://github.com/Lveyou/DND
要运行此例子请跑其中的DNDTest项目

作者：吴泔游
QQ：1339484752
日期：2017-09-28