 | | | Timers and global variables | Timers and global variables 2004-01-15 - By Chad Armstrong
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Hello:
I've been working on some new gaming concepts for my own little game.
I want to be able to implement a background timer which can slowly
increment things like health and mana points (for an example) while the
character waits or rests.
Since my game runs on Windows, Linux, and Macintosh (OS 8-X), I want to
keep this as platform neutral as possible. My program is written in
C/C++. Here is some example code I've written:
#include <time.h>
#include <stdio.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <unistd.h>
extern int health = 10;
int main()
{
int i = 0;
int time_passing = 2;
int wTime = time(NULL) + time_passing;
int child_proc = 0;
char ch = 'y';
child_proc = fork();
if (0 == child_proc)
{
printf("Timer started: %d\n", time(NULL));
for (i = 0; i < 5; i++)
{
while (time(NULL) < wTime)
{
}
health += 2;
printf("%d ", health);
wTime = time(NULL) + time_passing;
}
}
else if (child_proc > 0)
{
while (ch != 'n' && ch != 'N')
{
printf("Would you like to see your health? (y/n) ");
scanf(" %c", &ch);
if ('y' == ch || 'Y' == ch)
{
printf("Your health: %d\n", health);
}
}
wait(0);
}
printf("It's all over: %d\n", health);
return 0;
}
The good news is that the timer is working just fine for what I need.
I don't need a nanosecond precision timer, so just counting by standard
seconds works just fine.
What isn't working for me in this example is how I'm trying to create a
background job, yet have the information which is modified to remain
global. In this example, the health variable is incremented by the
child process, but not by the parent process. In my game I'll need a
way so there is global data. Yes, I might need to lock some
information from time to time (mutexes and such). Is there a better
way to handle running a background process than just a simple fork?
Should I consider using threads instead? Keep in mind that I'm trying
to steer away from system specific APIs such as NSTask or NSThread.
Thanks.
Chad Armstrong
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