How to assess frames per second?

BlitzMax Forums/BlitzMax Programming/How to assess frames per second?

ImaginaryHuman

(Posted 2004) [#1]

I wonder if someone(s) can confirm whether this following program is correct to assess the frames-per-second framerate of a given loop (heavily commented for your delectation)..... I used to go by knowing what the refresh rate of the display is (e.g. 50Hz and doing the math in comparison to that benchmark, but this needs to be htz independent). Millisecs() is 1000ths of a second right?

'Is this a correct program to read the frames per second? ..........:

Local counter:Int=MilliSecs() 'Store current MilliSecs() reading
Local passage:Int=0 'Initialize passage of time since last frame
Local m:Int=0 'Initialize temporary variable for math
Local fps:Int=0 'Initialize frames per sercond result variable
Repeat 'keep going
'
'do Max2D graphics processing stuff here
'
m=MilliSecs() ' Get the current MilliSecs() so that the number is consistent
passage=m-counter 'Passage of time since the last iteration of the loop
fps=1000/passage 'Fps is 1000 (millisecs) / millisecs since last loop?
counter=m ' Store current reading for next time
SetRotation 0 'Undo rotation settings from earlier in the graphics stuff
SetScale 1,1 'Undo scale from earlier too
DrawText fps+"fps",0,0 'So that this text draws right - the framerate
Flip ' Flip the backbuffer into view
Until KeyHit(KEY_ESCAPE) 'keep going until escape key hit

zeedoktor

(Posted 2004) [#2]

Looks about right. What gets me tho is the int being used for millisecs. shouldn't that be a long?

ImaginaryHuman

(Posted 2004) [#3]

I thought Int's were 32bit, same thing? otherwise it would be a double?

zeedoktor

(Posted 2004) [#4]

woops. wrong basic. i was assuming int (as in C and powerbasic) is 16bit. but you're right, it's 32bit.

Tibit

(Posted 2004) [#5]

I have always found this more stable and exact. I pasted yours into the fireworks demo and it changes way to much (unreadable for me).

'FPS_Counter    <> Runs And displays the FPS
'--------------------------------------------
  SetRotation 0 'Undo rotation 
  SetScale 1,1 'Undo scale
		
  FPS_Counter=FPS_Counter+1
			
  If FPS_Counter_time+1000 =< MilliSecs()
        FPS=FPS_Counter' <- Frames/Sec
        FPS_Counter=0
        FPS_Counter_time=MilliSecs()	
  EndIf
					
  DrawText "Current FPS: "+FPS,20,20
'--------------------------------------------

This is porbably not optimal, but it gives a accurate FPS for tweaking