Problem with basic renderer - not smooth enough
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From: Ikke on 20 Mar 2010 12:38 "winapi" <apiwin(a)hotmail.com> wrote in news:ho1088$3pq$1(a)speranza.aioe.org: > The reason your animation is jerky, is that you can only update in > increments of > "one" using the GDI. If you have noticed, coordinates use integer > values, so the best you can hope for, is an increment of += 1, not += > 0.1. This is not possible. if you try, you will see your shape remains > static.You might want > to try GDI+, this will give you better results than the standard GDI. > > See example code below, just change SetTimer value of 1000(one second) > to what ever. You will why the animation is jery using GDI . . . . . Thanks for the explanation - I realise that the movement of the ellipse will always be in increments of 1 (never smaller), but that's not the type of jerkiness I was experiencing. It was more of an impression that, from time to time, the ellipse got "stuck" behind something. As in your code example, the cube moves 1 pixel every second. Suppose it would move 1 pixel the next ten seconds, and then suddenly move 1 pixel after 1.5 seconds, you'd notice the delay. That's the jerkiness I was experiencing. Anyway, I changed my code to use the QueryPerformanceCounter (like Scott said), and the improvement is incredible! The increments are of course still per pixel, but the timing is a lot more accurate. Thanks! Ikke
From: winapi on 20 Mar 2010 16:04 Well, that will teach me for browsing over code. It seems your code is taken care of the incremental update to give that smoothness. Sorry for my misleading comments, seems I should pay more attention. I wonder if timeGetTime() would work also, although QueryPerformanceCounter is obviously better. "Ikke" <ikke(a)hier.be> wrote in message news:Xns9D41B2D496E75ikkehierbe(a)69.16.176.253... > N0Spam(a)daqarta.com (Bob Masta) wrote in news:4ba2257d.396212(a)news.eternal- > september.org: > > <snip> >>>QueryPerformanceCounter updates vastly faster. You will initially >>>have to use QueryPerformanceFrequency to translate into time periods: >>>They differ on different machines. >>> >> Another approach is to use a multi-media timer >> (timeBeginPeriod, timeSetEvent, etc.), which can >> be set to fire every msec. <snip> > > Thank you Scott and Bob, I have changed my code to use the > QueryPerformanceCounter, and I added a variable onscreen to check the > improvement. > > When I used GetTickCount, the ellipse would be moved (on average) 65 times > per second (like you said, Scott, every 15 ms). As soon as I switched to > QueryPerformanceCounter, the movement become very fluent, and the ellipse > is being moved at a rate of 995 times per second! > > Thanks again, > > Ikke
From: Ikke on 20 Mar 2010 20:48
"winapi" <apiwin(a)hotmail.com> wrote in news:ho39p2$np9$1(a)speranza.aioe.org: > Well, that will teach me for browsing over code. It seems your code is > taken care of the incremental update to give that smoothness. Sorry > for my misleading comments, > seems I should pay more attention. I wonder if timeGetTime() would > work also, although > QueryPerformanceCounter is obviously better. No problem - all comments are welcome! I don't know whether or not timeGetTime() works, I haven't tried it (yet). Thanks, Ikke |