Frames per second

By the way I''m programming in C++ so a little example or source code can be very helpful.

bool CText::renderFPS(D3DCOLOR color, float timeDelta)
{
	if( _font )
	{
		_frameCnt++;

		_timeElapsed += timeDelta;

		if(_timeElapsed >= 1.0f)
		{
			_fps = (float)_frameCnt / _timeElapsed;

			sprintf(_fpsString, "%f", _fps);
			_fpsString[8] = ''\0''; // mark end of string


			_timeElapsed = 0.0f;
			_frameCnt    = 0;
		}

		_font->DrawText(20, 20, color, _fpsString);	
	}
	return true;
}

I leave the rest up to you.

I have seen this asked before, but do not understand why.

When I first was wondering how to do this, I said to myself "If I can''t figure out how to calculate the number of frames per second then how in the world am I ever going to make it do anything cool?"

That said, I will give you several hints, but I hope noone actually answers your question so that you can learn on your own.

1) You have to code it yourself, it''s so simple that there aren''t any library functions for it in DirectX.
2) You do not actually need to wait one second to determin the actual number of frames per second, you can predict.
3) You may wish to take an average over a period of time (say 1/2 second) so that your FPS counter doesn''t flicker between two numbers every frame making it unreadable.

-SniperBoB-

well crap.... i was 2 slow

What is the timeDelta variable, where is it come from, how do I declare it?

Forget it my mistake!!!

No, I steel doesn''t understandhow the timeDelta gets the time between the last time the function was called and this time?

But how do I know that One second past, in the example the timeDelta variable gives us the time between frame to frame, when I add all of the timeDelta and get to 1, the I know that 1 second has past, but where do I get the timeDelta, the time btween frame to frame?

Lookup GetTickCount().

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Where can I find it, can you give me a simple source code so I''ll see in which .h file this function is?

DorRaba, take a look at the C++ help files. GetTickCount is one of the functions that can tell you how much time has passed.

[edited by - Erzengeldeslichtes on January 19, 2004 12:20:15 PM]

Here is a little FPS Timer class I threw together. You can use it as is, or just go through the code to learn how it works. There''s really very little to it.

http://www.drunkenhyena.com/docs/dhFPSTimer.phtml


Stay Casual,

Ken
Drunken Hyena