FPS & Timing calculating

Retro1234 · 17 December 2011, 22:52

Im running way to fast on 68020 how do I calculate FPS or/and calculate a timer for maintaing a constant speed?

pmc · 18 December 2011, 12:51

Maybe tie your code to only executing during vertical blanking? That would keep the speed at a constant 50fps (60 on NTSC machines) regardless of the clock speed of the processor executing the code.

Retro1234 · 18 December 2011, 13:11

Thank you for your reply and suggestion and I know its being awkward but I would like the timer not to rely on vertical blanking

So im thinking no matter what the cpu I need work out the difference without causing a pause - have a max speed that I can cap.

pmc · 18 December 2011, 15:50

Fair enough

You could setup a timer interrupt which would then allow you to choose (by setting the timer duration) how regularly your code would execute maybe?

Anakirob · 18 December 2011, 17:37

Umm, so you want to calculate FPS and/or cap frame rate but you don't want to count vertical blanks?! Seems like an oxymoron to me.

Anyway, many years ago with a piece of Blitz2 code I had a problem where sometimes my main loop would run at 50FPS and sometimes it would slow down to 25. I wanted a constant frame rate and felt that 25 FPS was fine. I resolved the issue like this:

Code:

SetInt 5
  VB+1
End SetInt

.mainloop
  VB=0

<some code>

  WHILE VB<2 ; this is where you set your cap
    VWait
  WEND

Goto mainloop

Retro1234 · 18 December 2011, 19:26

Thanks for your replys I think your right ill have to have a play - If anyone else has anything to add please do

17 December 2011, 22:52	#1
Retro1234 Phone Homer Join Date: Jun 2006 Location: 5150 Posts: 5,775	FPS & Timing calculating Im running way to fast on 68020 how do I calculate FPS or/and calculate a timer for maintaing a constant speed?

18 December 2011, 13:11	#3
Retro1234 Phone Homer Join Date: Jun 2006 Location: 5150 Posts: 5,775	Thank you for your reply and suggestion and I know its being awkward but I would like the timer not to rely on vertical blanking So im thinking no matter what the cpu I need work out the difference without causing a pause - have a max speed that I can cap. Last edited by Retro1234; 18 December 2011 at 13:16.

18 December 2011, 17:37	#5
Anakirob Unregistered User Join Date: Nov 2005 Location: Tasmania Age: 42 Posts: 893	Umm, so you want to calculate FPS and/or cap frame rate but you don't want to count vertical blanks?! Seems like an oxymoron to me. Anyway, many years ago with a piece of Blitz2 code I had a problem where sometimes my main loop would run at 50FPS and sometimes it would slow down to 25. I wanted a constant frame rate and felt that 25 FPS was fine. I resolved the issue like this: Code: SetInt 5 VB+1 End SetInt .mainloop VB=0 <some code> WHILE VB<2 ; this is where you set your cap VWait WEND Goto mainloop

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18 December 2011, 12:51	#2
pmc gone Join Date: Apr 2007 Location: completely gone Posts: 1,596	Maybe tie your code to only executing during vertical blanking? That would keep the speed at a constant 50fps (60 on NTSC machines) regardless of the clock speed of the processor executing the code.

18 December 2011, 15:50	#4
pmc gone Join Date: Apr 2007 Location: completely gone Posts: 1,596	Fair enough You could setup a timer interrupt which would then allow you to choose (by setting the timer duration) how regularly your code would execute maybe?

18 December 2011, 19:26	#6
Retro1234 Phone Homer Join Date: Jun 2006 Location: 5150 Posts: 5,775	Thanks for your replys I think your right ill have to have a play - If anyone else has anything to add please do

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