我正在用 C++ OpenGL 制作一个小游戏。update()
通常在程序每次运行代码时调用一次。我试图将其限制为每秒 60 次(我希望游戏在不同速度的计算机上以相同的速度更新)。
下面包含的代码运行一个计时器,update()
一旦计时器 >= 0.0166666666666667(每秒 60 次),就应该调用它。然而,该语句if((seconds - lastTime) >= 0.0166666666666667)
似乎每秒只触发一次。有谁知道为什么?
在此先感谢您的帮助。
//Global Timer variables
double secondsS;
double lastTime;
time_t timer;
struct tm y2k;
double seconds;
void init()
{
glClearColor(0,0,0,0.0); // Sets the clear colour to white.
// glClear(GL_COLOR_BUFFER_BIT) in the display function
//Init viewport
viewportX = 0;
viewportY = 0;
initShips();
//Time
lastTime = 0;
time_t timerS;
struct tm y2k;
y2k.tm_hour = 0; y2k.tm_min = 0; y2k.tm_sec = 0;
y2k.tm_year = 100; y2k.tm_mon = 0; y2k.tm_mday = 1;
time(&timerS); /* get current time; same as: timer = time(NULL) */
secondsS = difftime(timerS,mktime(&y2k));
printf ("%.f seconds since January 1, 2000 in the current timezone \n", secondsS);
loadTextures();
ShowCursor(true);
glBlendFunc(GL_ONE, GL_ONE_MINUS_SRC_ALPHA);
}
void timeKeeper()
{
y2k.tm_hour = 0; y2k.tm_min = 0; y2k.tm_sec = 0;
y2k.tm_year = 100; y2k.tm_mon = 0; y2k.tm_mday = 1;
time(&timer); /* get current time; same as: timer = time(NULL) */
seconds = difftime(timer,mktime(&y2k));
seconds -= secondsS;
//Run 60 times a second. This limits updates to a constant standard.
if((seconds - lastTime) >= 0.0166666666666667)
{
lastTime = seconds;
update();
//printf ("%.f seconds since beginning program \n", seconds);
}
}
timeKeeper()
在 int 中调用WINAPI WinMain
,而程序是!done
编辑:
感谢那些提供帮助的人,您为我指明了正确的轨道。正如下面的答案中提到的那样<ctime>
,没有毫秒精度。因此,我实现了以下具有正确准确性的代码:
double GetSystemTimeSample()
{
FILETIME ft1, ft2;
// assume little endian and that ULONGLONG has same alignment as FILETIME
ULONGLONG &t1 = *reinterpret_cast<ULONGLONG*>(&ft1),
&t2 = *reinterpret_cast<ULONGLONG*>(&ft2);
GetSystemTimeAsFileTime(&ft1);
do
{
GetSystemTimeAsFileTime(&ft2);
} while (t1 == t2);
return (t2 - t1) / 10000.0;
}//GetSystemTimeSample
void timeKeeper()
{
thisTime += GetSystemTimeSample();
cout << thisTime << endl;
//Run 60 times a second. This limits updates to a constant standard.
if(thisTime >= 16.666666666666699825) //Compare to a value in milliseconds
{
thisTime = seconds;
update();
}
}