3D / FPS相機問題-SDL2

Question

我的代碼有問題，我正在嘗試制作第一人稱3D相機。 我使用SDL_GetKeyboardState（NULL）來獲取按下的鍵。

當我按下已定義的鍵之一時，什么也沒發生，為什么？

相機（控制）：

void Control(float movevel, float mousevel, bool mi, SDL_Window* window)
{
if (mi)  //if the mouse is in the screen
{
    int MidX = 640 / 2;   //middle of the screen
    int MidY = 480 / 2;
    SDL_ShowCursor(SDL_DISABLE);    //we don't show the cursor
    int tmpx, tmpy;
    SDL_GetMouseState(&tmpx, &tmpy); //get the current position of the cursor
    camYaw += mousevel*(MidX - tmpx);   //get the rotation, for example, if the mouse current position is 315, than 5*0.2, this is for Y
    camPitch += mousevel*(MidY - tmpy); //this is for X
    lockCamera();
    //SDL_WarpMouse(MidX, MidY);       //move back the cursor to the center of the screen
    SDL_WarpMouseInWindow(window, MidX, MidY);

    const Uint8* kstate = SDL_GetKeyboardState(NULL);

    if (kstate[SDLK_w])
    {
        if (camPitch != 90 && camPitch != -90)
        {       //if we are facing directly up or down, we don't go forward, it will be commented out, when there will be gravity
            moveCamera(movevel, 0.0);        //move forward
        }

        moveCameraUp(movevel, 0.0);      //move up/down
    }

    if (kstate[SDLK_s])
    {
        //same, just we use 180 degrees, so we move at the different direction (move back)
        if (camPitch != 90 && camPitch != -90)
        {
            moveCamera(movevel, 180.0);
        }

        moveCameraUp(movevel, 180.0);
    }

    if (kstate[SDLK_a])
    {       //move left
        moveCamera(movevel, 90.0);
    }

    if (kstate[SDLK_d])
    {  //move right
        moveCamera(movevel, 270);
    }
}

glRotatef(-camPitch, 1.0, 0.0, 0.0);
glRotatef(-camYaw, 0.0, 1.0, 0.0);
}

主（循環）

while (running)
{
    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
    glLoadIdentity();

    SDL_Event ev;
    while (SDL_PollEvent(&ev))
    {
        switch (ev.type)
        {
            case SDL_QUIT:
                running = false;
                break;
            case SDL_KEYDOWN:
                int x, y;

                SDL_GetMouseState(&x, &y);
                Main::handleKeys(ev.key.keysym.scancode, x, y);
                break;
        }
    }

    Main::update(window);
    Main::render(window);

    SDL_GL_SwapWindow(window);
}

主要（更新）：

void Main::update(SDL_Window* window)
{
Control(0.2, 0.2, mousein, window);
UpdateCamera(0.2); //move the camera to the new location
}

Answer 1

您應該在平移相機之前調用glRotatef函數，否則它將繞原點而不是其位置旋轉

Answer 2

使用SDL_PumpEvents（）更新狀態數組。 （來自SDL_GetKeyboardState（）Wiki）。 我相信，如果您這樣做：

SDL_PumpEvents();
SDL_GetKeyboardState(NULL);

您應該得到想要的結果。 （顯然，每個循環都需要SDL_PumpEvents以及SDL_GetKeyboardState）

（編輯）另一個選擇：

    case SDL_KEYDOWN:
        switch(event.key.keysym.sym){
            case SDLK_w
                (... code)
                break;
            case SDLK_s:
                (... code)
                break;
            case SDLK_a:
                (... code)
                break;
            case SDLK_d:
                (... code)
                break;

您也可以將event.key.keysym.sym發送給函數，並在過程中使用它。