Proper FPS counter increment http://www.allegro.cc/forums/view/590641 Allegro.cc Forum Thread matthew@allegro.cc (Matthew Leverton) Thu, 22 Mar 2007 09:02:44 +0000

Howdy,

I just need to know when to increment my framecounter in code like this:

1volatile int speed_counter = 0;
2 
3volatile int framecounter = 0;
4volatile int framerate = 0;
5 
6 void IncSpeedCounter()
7 {
8 speed_counter++;
9 }
10 
11 END_OF_FUNCTION(IncSpeedCounter)
12 
13 void GetFR()
14 {
15 framerate = framecounter;
16 framecounter = 0;
17 }
18 
19 END_OF_FUNCTION(GetFR)
20 
21 void PlayGame()
22 {
23 LOCK_VARIABLE(speed_counter);
24 LOCK_FUNCTION(IncSpeedCounter);
25 
26 install_int_ex(IncSpeedCounter, BPS_TO_TIMER(60));
27 install_int_ex(GetFR, BPS_TO_TIMER(1));
28 
29 while (!game_over)
30 {
31 while (speed_counter > 0)
32 {
33 //Should I increment it in here? (framecounter++)
34 update_game_logic();
35 speed_counter--;
36 }
37 
38 //Or should I increment it here? (framecounter++)
39 update_display();
40 }
41 }

]]> no-reply@allegro.cc (blargmob) Wed, 21 Mar 2007 05:42:47 +0000

If you want to count the number of redraws, then the latter. If you want the number of (logical) updates, the former. I assume you want the first, so you need the latter. (Wow, now that was perfectly confusing, wasn't it? :P)

Put it right above that update_display();.

]]> no-reply@allegro.cc (Indeterminatus) Wed, 21 Mar 2007 05:46:39 +0000

If I increment at the latter, than anything I pass to BPS_TO_TIMER() doesn't affect the FPS, and when there is actually only 1 Frame Per Second, it says that there is like 100 Frames Per Second. How do fix this and have control of my FPS?

]]> no-reply@allegro.cc (blargmob) Wed, 21 Mar 2007 06:00:01 +0000

Something like this will prevent extraneous redraws:

1bool need_redraw = false;
2while(!game_over)
3{
4 while(speed_counter > 0)
5 {
6 update_game_logic();
7 speed_counter--;
8 need_redraw = true;
9 }
10 
11 if(need_redraw)
12 {
13 framecounter++;
14 update_display();
15 need_redraw = false;
16 }
17}

]]> no-reply@allegro.cc (CGamesPlay) Wed, 21 Mar 2007 06:03:46 +0000

Problem fixed.
Thanks!
;D

]]> no-reply@allegro.cc (blargmob) Wed, 21 Mar 2007 06:41:05 +0000

You might also want to add

while(speed_counter == 0)
  rest(1);

or something like that :-/

]]> no-reply@allegro.cc (The Unknown) Thu, 22 Mar 2007 03:19:47 +0000

The Unknown: would you want that to be in a while() loop, or a simple if() statement?

1volatile int speed_counter = 0;
2 
3volatile int framecounter = 0;
4volatile int framerate = 0;
5 
6 
7void incrementSpeedCounter()
8{
9 speed_counter++;
10}
11END_OF_FUNCTION(incrementSpeedCounter)
12 
13 
14void getFrameRate()
15{
16 framerate = framecounter;
17 framecounter = 0;
18}
19END_OF_FUNCTION(getFrameRate)
20 
21void PlayGame()
22{
23 LOCK_VARIABLE(speed_counter);
24 LOCK_FUNCTION(incrementSpeedCounter);
25 
26 install_int_ex(incrementSpeedCounter, BPS_TO_TIMER(60));
27 install_int_ex(getFrameRate, BPS_TO_TIMER(1));
28 
29 while (!game_over)
30 {
31 while (speed_counter > 0)
32 {
33 update_game_logic();
34 speed_counter--;
35 need_redraw = true;
36 }
37 
38 // Should this be a "while" or an "if"?
39 if (speed_counter == 0)
40 rest(1);
41 
42 if (need_redraw)
43 {
44 framecounter++;
45 update_display();
46 need_redraw = false;
47 }
48 }
49}

]]> no-reply@allegro.cc (TeamTerradactyl) Thu, 22 Mar 2007 03:29:04 +0000

TT,

Your code will call the rest(1) nearly every time it loops past it. Would this cause more logical updates to occur for every screen update than if it were placed before the while loop(as shown below), because the while block is exited when speed_counter is zero?

1 while (!game_over)
2 {
3 // Should this be a "while" or an "if"?
4 if (speed_counter == 0)
5 rest(1);
6 
7 while (speed_counter > 0)
8 {
9 update_game_logic();
10 speed_counter--;
11 need_redraw = true;
12 }
13 
14 if (need_redraw)
15 {
16 framecounter++;
17 update_display();
18 need_redraw = false;
19 }
20 }

I'd say it wouldn't make much of a difference whether a "while" or an "if" was used if the code given was all the processing that is done (but I'd be interested if someone can show a scenario where it would have an impact). But personally I go for an "if". Do the rest(!) command once and then check everything else before testing again whether the rest(!) should be called.

]]> no-reply@allegro.cc (HardTranceFan) Thu, 22 Mar 2007 04:44:51 +0000

an if statement would run quicker than a while loop, since the amount of times a while loop needs to run is unknown... but, the difference in negligable :-/

Infact, to save a whole new if/while statement, just add it an an else to if(need_redraw)

It would still make no difference though.

]]> no-reply@allegro.cc (The Unknown) Thu, 22 Mar 2007 05:57:34 +0000

The amount of times the while statement needs to be run is known to be one. Since rest will sleep for 10 milliseconds, and his timer fires more frequently than that, the condition will always be true after a rest.

[append]
So yes, the faster is if, but the difference is microscopic.

]]> no-reply@allegro.cc (CGamesPlay) Thu, 22 Mar 2007 09:02:44 +0000