計算FPS使用SDL 2.0

Question

#define FPS_INTERVAL 1.0 //seconds. 

Uint32 fps_lasttime = SDL_GetTicks(); //the last recorded time. 
Uint32 fps_current; //the current FPS. 
Uint32 fps_frames = 0; //frames passed since the last recorded fps. 

// you would initalise these in a main method, really. 

void loop() 
{ 
    //YOUR PAINTING STUFF HERE... 
    //********// 

    fps_frames++; 
    if (fps_lasttime < SDL_GetTicks() - FPS_INTERVAL*1000) 
    { 
     fps_lasttime = SDL_GetTicks(); 
     fps_current = fps_frames; 
     fps_frames = 0; 
    } 
} 

我把上面的代碼來自： http://sdl.beuc.net/sdl.wiki/SDL_Average_FPS_Measurement

我理解的代碼，但FPS_INTERVAL混淆了我，因爲我實在無法理解爲什麼需要它的if語句。有人可以解釋這個嗎？

而且我也必須使用Uint32或將任何int做這項工作，爲什麼？

Answer 1

SDL_GetTicks()返回毫秒數; FPS_INTERVAL指定計數幀的秒數（此處爲-1）;它乘以1,000得到毫秒數。

回覆：Uint32 - 那就是SDL_GetTicks()返回。你會使用什麼其他類型，爲什麼？