StartDrawing(ScreenOutput()):StopDrawing()

Psychophanta · Post by **Psychophanta** » Sat Mar 19, 2005 7:18 pm

These two functions eats a lot of CPU time.
Sorry if i am a purist of saving resources, but in this case, i think it is a disproportionate consumption. About 80% of CPU inter-frame time at 60Hz.

Can be done something?

filperj · Post by **filperj** » Sat Mar 19, 2005 10:41 pm

Well...
-1: Test that little test.
-2: Note the results.
-3: Comment the "If StartDrawing..." line.
-4: Test again.
-5: Compare results.
-6:

Code: Select all


InitSprite()
If OpenScreen(800,600,32,"")
   CreateSprite(0,100,100)
   BeginTime=ElapsedMilliseconds()
   For it=1 To 3000
      start=ElapsedMilliseconds()
      If StartDrawing(ScreenOutput()) : StopDrawing() : EndIf ; <- Comment me !
      Drawtime+(ElapsedMilliseconds()-start)
      ClearScreen(100,100,80)
      start=ElapsedMilliseconds()
      For itspr=1 To 400
         DisplaySprite(0,Random(700),Random(500))
      Next
      SpriteTime+(ElapsedMilliseconds()-start)
      FlipBuffers(0)
   Next
   TotalTime=ElapsedMilliseconds()-BeginTime
   CloseScreen()
   advert$="Total time : "+Str(TotalTime)+#lf$+"Drawing time : "+Str(drawtime)
   advert$+(#lf$+"Sprites time : "+Str(SpriteTime))
   advert$+(#lf$+"Drawing+Sprites : "+Str(DrawTime+SpriteTime))
   MessageRequester("",advert$)
EndIf

Psychophanta · Post by **Psychophanta** » Sat Mar 19, 2005 11:11 pm

Nice snip to demonstrate it.
Look this:

Code: Select all

InitSprite() 
If OpenScreen(800,600,32,"") 
   CreateSprite(0,100,100) 
   BeginTime=ElapsedMilliseconds() 
   For it=1 To 3000 
      start=ElapsedMilliseconds() 
      StartDrawing(ScreenOutput()) : StopDrawing() 
      Drawtime+(ElapsedMilliseconds()-start) 
      ClearScreen(100,100,80) 
      start=ElapsedMilliseconds() 
      For itspr=1 To 160 
         DisplaySprite(0,Random(700),Random(500)) 
      Next 
      SpriteTime+(ElapsedMilliseconds()-start) 
      FlipBuffers(0) 
   Next 
   TotalTime=ElapsedMilliseconds()-BeginTime 
   CloseScreen() 
   advert$="Total time : "+Str(TotalTime)+#lf$+"Drawing time : "+Str(drawtime) 
   advert$+(#lf$+"Sprites time : "+Str(SpriteTime)) 
   advert$+(#lf$+"Drawing+Sprites : "+Str(DrawTime+SpriteTime)) 
   MessageRequester("",advert$) 
EndIf

Time used by:
StartDrawing(ScreenOutput()) : StopDrawing()
is about time used by:
For itspr=1 To 160
DisplaySprite(0,Random(700),Random(500))
Next

Incredible

filperj · Post by **filperj** » Sat Mar 19, 2005 11:48 pm

Yes but... Did you try to remove the StartDrawing() ? The code won't run that much faster. And as I used FlipBuffers(0) it's not a matter of VSync.

I suppose that there is a "Mysterious Operation" (Let's call it MOP) which has to be done before each FlipBuffers().
If I guess right, when you call StartDrawing(Screenoutput()), it executes the MOP, and when you call FlipBuffers(), it executes the MOP IF the MOP has not been executed before.

So StartDrawing() looks slow but is not...

:roll:

Psychophanta · Post by **Psychophanta** » Sun Mar 20, 2005 12:21 am

so strange :roll:
any answer

Ralf · Post by **Ralf** » Sun Mar 20, 2005 6:08 am

hi Psychophanta! i remember someone posted this some time before and shared an example how to speed it up with direct DX access or whatever it was!? i am not really sure and i havent found the posting yet. maybe you have more luck!?