c++ - SDL_Jostick 正在发送奇怪的整数

Question

我在尝试使用 SDL(版本 2.0.3)处理 SDL/OpenGL/C++ 程序中的多个游戏 Controller 时遇到了一些问题。

我正在使用 SDL_PollEvent(&m_events) 循环更新事件并使用 switch(m_events.type) 查找 SDL_JOYBUTTONDOWN(或 SDL_JOYBUTTONUP/SDL_JOYAXISMOTION/SDL_HATMOTION)事件。我想要的是使用 m_events.jbutton.which 和 m_events.jbutton.button(或轴和帽子的等效项)的值来更新包含我的 Controller 状态的数组。

我使用的是 Windows 7 Pro 64 位和 Code::Blocks 13.12，但它不应该改变任何东西。

这是我的(调试)代码，我试图只保留相关部分:

主要.cpp

#include "SceneOpenGL.h"
int main(int argc, char *argv[])
{
  SceneOpenGL scene(/* some args for window size */);

  if(!scene.initWindow())
    return -1;

  scene.mainLoop();

  return 0;
}

场景OpenGL.h

#ifndef SCENEOPENGL_H_INCLUDED
#define SCENEOPENGL_H_INCLUDED
#include <iostream>
#include "Input.h"
#include <SDL2/SDL.h>

class SceneOpenGL
{
public:
  SceneOpenGL(/* some args for window size */);
  ~SceneOpenGL();
  bool initWindow();
  void mainLoop();

private:
  SDL_Window* m_window;
  SDL_Event m_event;
  Input m_input;
  bool m_useJoysticks;
};
#endif

场景OpenGL.cpp

SceneOpenGL::SceneOpenGL(/* some args for window size */) :
  m_window(0), m_input()
{
  if(SDL_NumJoysticks())
    m_useJoysticks = true;
}

bool SceneOpenGL::initWindow()
{
  if(SDL_Init( SDL_INIT_VIDEO | SDL_INIT_JOYSTICK ) == -1)
  {
    std::cout << "Error while initializing SDL : " << SDL_GetError() << std::endl;
    SDL_Quit();
    return false;
  }
  /*
  **** Creation of SDL Window and GLContext ****
  */
  return true;
}

void SceneOpenGL::mainLoop()
{
  if(m_useJoysticks)
  {
    m_input.openJoysticks();
    SDL_JoystickEventState(SDL_ENABLE);
  }

  while(!m_input.terminate()) // m_input.terminate() sends true when SDL receives SDL_WINDOWEVENT_CLOSE event
  {
    m_input.updateEvents(); // this is the other loop where I update the joystick, keyboard & mouse state

    /* ...
    **** moving opengl objects & render ****
    */
  }
}

输入.h

#ifndef INPUT_H_INCLUDED
#define INPUT_H_INCLUDED
#include <SDL2/SDL.h>
#include <iostream>

class Input
{
public:
  Input();
  ~Input();
  void updateEvents();
  bool terminate() const;

  void openJoysticks();

private:
  SDL_Event m_events;

  int m_numJoysticks;
  SDL_Joysticks* m_joysticks[4]; // Array containing the first 4 joysicks

  bool m_terminate; // used for ending program
};

输入.cpp

#include "Input.h"

Input::Input() :
  m_numJoysticks(0), m_terminate(false)
{}

Input::~Input()
{
  for(int i(0); i < SDL_NumJoysticks(); i++)
    SDL_JoystickClose(m_joysticks[i]); // Closes joysticks before exiting
}

void Input::openJoysticks()
{
  m_numJoysticks = SDL_NumJoysticks; // Counts the connected joysticks
  if(m_numJoysticks > 4)
    m_numJoysticks = 4; // Sets maximum joysticks to 4

  for(int i(0); i < m_numJoysticks; i++)
  {
    m_joysticks[i] = SDL_JoystickOpen(0) // Open existing joysticks
    std::cout << "Joystick #" << i << " OK" << std::endl;
  }
}

void Input::updateEvents()
{
  while(SDL_PollEvent(&m_events))
  {
    switch(m_events.type)
    {
    /* ... Keyboard and mouse events, no problem there */
    case SDL_JOYBUTTONDOWN:
      std::cout << "JOYBUTTONDOWN" << std::endl;
      std::cout << "type : " << m_events.jbutton.type << std::endl;
      std::cout << "which : " << m_events.jbutton.which << std::endl;
      std::cout << "button : " << m_events.jbutton.button << std::endl;
      std::cout << "state : " << m_events.jbutton.state << std:: endl << std::endl;
      break;

    /* ... Same thing for SDL_JOYBUTTONUP, SDL_JOYAXISMOTION, SDL_JOYHATMOTION  */

    case SDL_WINDOWEVENT:
      if(m_events.window.event == SDL_WINDOWEVENT_CLOSE)
        m_terminate = true; // end program
      break;

    default:
      break;
    }
  }
}

bool Input::terminate() const
{
  return m_terminate;
}

下面是我在 x360 Controller 上按 A、B、X、Y(= 按钮 0、1、2 和 3)时的控制台输出:

Joystick #0 OK
JOYBUTTONDOWN
type : 1539
which : 65536
button : §
state : Ý

JOYBUTTONDOWN
type : 1539
which : 1996554496
button :
state :

JOYBUTTONDOWN
type : 1539
which : 1996554752
button :
state :

JOYBUTTONDOWN
type : 1539
which : 1996555008
button :
state :

Process returned 0 (0x0)   execution time : 7.437 s
Press any key to continue.

如您所见，它似乎不太正常。我什至有时会为相同的输入得到不同的值(就像这里按下第一个按钮)，但我注意到“哪个”值之间的差异是 256，所以它不是完全随机的。如果我重新启动程序或按同一个按钮两次，这些值基本相同。好吧，似乎“event.jbutton.which”包含按钮索引的信息(应该是 Uint8)

不知道是我做错了还是SDL2的bug。

Answer 1

您的数字似乎是各种标志字段的按位或，可能带有值字段。

用十六进制检查它们会很明显:​​

1996554752 = 0x77010200

1996554496 = 0x77010100

1996555008 = 0x77010300

看起来您的“按钮编号”可能位于第 15-8 位，即值 2、1、3

这几乎肯定包含在适当的文档中