SDL2崩溃白色InputHandler鼠标运动

无警告，无错误。编译得很好，但是在update函数的底部，以下行使程序崩溃:

(*m_mousePosition).setX(event.motion.x);
(*m_mousePosition).setY(event.motion.y);

完整的代码:

#include <SDL2/SDL.h>
#include <vector>
#include "Vector2D.h"
using namespace std;
#ifndef INPUTHANDLER_H
#define INPUTHANDLER_H
enum mouse_buttons{
   LEFT = 0,
   MIDDLE = 1,
   RIGHT = 2
};
class InputHandler{
public:
    static InputHandler* Instance(){
        if(s_pInstance==0){
            s_pInstance= new InputHandler();
        }
        return s_pInstance;
    }
    void update(){
        if(event.type == SDL_MOUSEBUTTONDOWN){
            if(event.button.button == SDL_BUTTON_LEFT){
                m_mouseButtonStates[LEFT]=true;
            }
            if(event.button.button == SDL_BUTTON_MIDDLE){
                m_mouseButtonStates[MIDDLE]=true;
            }
            if(event.button.button == SDL_BUTTON_RIGHT){
                m_mouseButtonStates[RIGHT]=true;
            }
        }
        if(event.type == SDL_MOUSEBUTTONUP){
            if(event.button.button == SDL_BUTTON_LEFT){
                m_mouseButtonStates[LEFT]=false;
            }
            if(event.button.button == SDL_BUTTON_MIDDLE){
                m_mouseButtonStates[MIDDLE]=false;
            }
            if(event.button.button == SDL_BUTTON_RIGHT){
                m_mouseButtonStates[RIGHT]=false;
            }
        }
        if(event.type == SDL_MOUSEMOTION){
            (*m_mousePosition).setX(event.motion.x);
            (*m_mousePosition).setY(event.motion.y);
        }
    }
    SDL_Event* getEvent(){
        return &event;
    }
    void clear();

    bool getMouseButtonStates(int buttonNumber){
        return m_mouseButtonStates[buttonNumber];
    }
    Vector2D* getMousePosition(){
        return m_mousePosition;
    }
private:
    SDL_Event event;
    vector<bool> m_mouseButtonStates;
    Vector2D* m_mousePosition;
    InputHandler(){
        for(int i=0; i<3; i++){
            m_mouseButtonStates.push_back(false);
        }
    }
    ~InputHandler(){}
    static InputHandler* s_pInstance;
};
typedef InputHandler TheInputHandler;
#endif  /* INPUTHANDLER_H */

也许这是一个问题，但我不知道，我不能解决

============================== 新编辑 ======================================

现在我不使用指针了，但是我必须用两个参数初始化Vector2D。我把它放在InputHandler构造函数中:

InputHandler::InputHandler():m_position(0,0){
    for(int i=0; i<3; i++){
        m_mouseButtonStates.push_back(false);
    }
}

并给出以下错误:

InputHandler.cpp:12:30: error: member initializer 'm_position' does not name a non-static data member or base class
InputHandler::InputHandler():m_position(0,0){
                             ^~~~~~~~~~~~~~~

Vector2D类的定义:

#include<math.h>
using namespace std;
#ifndef VECTOR2D_H
#define VECTOR2D_H
class Vector2D {
public:
    Vector2D(float x, float y):m_x(x), m_y(y){}
    float getX(){return m_x;}
    float getY(){return m_y;}
    void setX(float x){m_x=x;}
    void setY(float y){m_y=y;}
    float length(){return sqrt(m_x*m_x + m_y*m_y);}
private:
    float m_x;
    float m_y;
};
#endif  /* VECTOR2D_H */