我正確計算我的FPS嗎？

Question

所以我在想，如果我是正確的計算我的FPS：

Uint32 delayFrom(float startTime, float endTime){ 
    return(endTime - startTime); 
} 


int main(){ 
    int numFrames = 0; 
    Uint32 startTime = SDL_GetTicks(); 
    while(!done){ 
     frameTime = 0; 
     float fps = (numFrames/(float)(SDL_GetTicks() - startTime))*1000; 
     cout << fps << endl; 
     SDL_Delay(delayFrom(frameTime, 1/60)); 
     ++numFrames; 
    } 
} 

Answer 1

int main() { 
    int numFrames = 0; 
    Uint32 startTime = SDL_GetTicks(); 
    while (!done) { 
    ++numFrames; 
    Uint32 elapsedMS = SDL_GetTicks() - startTime; // Time since start of loop 
    if (elapsedMS) { // Skip this the first frame 
     double elapsedSeconds = elapsedMS/1000.0; // Convert to seconds 
     double fps = numFrames/elapsedSeconds; // FPS is Frames/Seconds 
     cout << fps << endl; 
    } 
    SDL_Delay(1.0/60.0); // Use floating point division, not integer 
    } 
} 

Answer 2

frameTime的永遠不會被分配任何0以外想必這是一個錯誤。

Answer 3

cout可能比較緩慢，從而得到更精確的值，你需要分割時間測量和輸出結果。

int main(){ 
    int numFrames = 0;  
    long totalTime = 0; 
    while(!done){ 
     // measure time 
     const Uint32 startTime = SDL_GetTicks(); 
     SDL_Delay(1.0f/60.0f); 
     const Uint32 endTime = SDL_GetTicks(); 

     // calculate result 
     totalTime += endTime - startTime; 
     ++numFrames; 
     float fps = numFrames/(totalTime/1000.0); 
     cout << fps << endl; 
    } 
}