Thread: Pixle Calc. Problem

For the game i have been making i have been using some physics to create realistic, parabolic, movments.

i first use Vf = Vi + at to find the next velocity from the last one
then i change Vi = Vf in order to create the change in velocity
then DeltaY = Vi(Sin(theta)(DeltaTime) - 1/2(Gravity(DeltaTime^2)
then DeltaX = Vi(Cos(theta)(DeltaTime)
(i love physics)

the problem is that since i am having this program run at 60 frames per second i use 1/60 for my DeltaTime, right. but the chance from one position to the next it to small becouse the time change it to small so the object dose not move becouse you cant draw part of a pixle, and if i up the time frame it of corse moves way to fast.

Any one with any tricks on the subject plz tell me and thank you for your input

I have been looking around and have not been able to find any thing one implementing time, can some one point me in the right direction, that would be great.

it would also be great if some one could explain a little about how to implement what Perspective was talking about, after some thought i dont really understand how that would help me with my pixle problem becouse i would still be using small incremets of time, which would still not show up when the flote converts to int.

thanks for the help

You should probably look into high-resolution timers. Those other timers are junk.

QueryPerformanceFrequency
QueryPerformanceCounter

The way I do it (thanks to some guy over at www.gamedev.net):

Code:

// This function is called ONCE each frame
float Val2Proc()
{
	static double       time_elapsed;
	static __int64      pc1, pc2;
	static __int64      pf;

	QueryPerformanceCounter((LARGE_INTEGER*)&pc2);

	time_elapsed = double(pc2-pc1) / double(pf);
	QueryPerformanceFrequency((LARGE_INTEGER*)&pf);
	QueryPerformanceCounter((LARGE_INTEGER*)&pc1);

        // procPower is a global float i have. 50 is a number I just chose.
	procPower = (float)time_elapsed*50.0f;    
	return (float)time_elapsed;
}

Then, I multiply everything that should be timebased (like cameraspeed, the speed of an object) with procPower. There are lots of ways you could do it, this is one. most likely not the best way but I think it does the job just fine.

Depending on what hardware you support, always remember that the machine the game will want to run on / is capable of running on might not have harware timers. I personally support both hardware and multimedia timers in all my games for older computers.

Shakti, why do you return (float)time_elapsed;, when you have already set procPower to what you want? is it just to make the function more usefull by allowing the coder to also use it to return the time elapsed between frames if needed?

Also, why in "procPower = (float)time_elapsed*50.0f;" do you multiply time_elapsed by 50?

Also, why in "time_elapsed = double(pc2-pc1) / double(pf);" do you divide by the frequency pf?