Re: Problem gettting a smooth continous background scroll (SDL2)

If you send me a link to download your solution I can take a look to it
tomorrow morning and see if I see something wrong, I have free time and
willing to help. (I tried to check the tutorial but I'm lazy to compile
SDL_Image).

:)

2016-08-19 17:19 GMT+02:00 exerion <[email protected]>:

>
>
>
> BenoitRen wrote:
>
>
> -The duration of one frame when rendering at 60 frames per second is not
> 16 milliseconds, but 16.67 milliseconds (1000 / 60 = 16.67). This
> difference in timing adds up.
>
>
>
> Right. But I tried with different delays, speeds, etc. configurable while
> processing the scroll so I could see the changes in runtime.
> Problem is still there.
> I'm not completely sure if it's tearing. Looks so, if I understood
> correctly what tearing is.
>
>
>
>
> BenoitRen wrote:
>
>
> -Every frame you insert a waiting period of 16 milliseconds. This does not
> take into account the time it takes to process one frame between the delays.
>
>
>
>
> Right. But I tried to use more advanced timing control and the problem is
> still there.
>
>
>
>
> BenoitRen wrote:
>
>
> -SDL_Delay is not very reliable. The operating system's scheduler might
> decide to allocate some time to another process instead of yours at the
> time you expect control back.
>
>
>
>
> True. I was reading about that the last days and applied some timing
> methods withotu using SDL_Delay, related to previous suggestions. Some
> improvement but I still see the problem.
>
>
>
>
>
> BenoitRen wrote:
>
>
> There are two approaches you can take.
>
> One approach is using timers, which Lazy Foo' also explains in one of his
> tutorials. To solve the problem of one second not cleanly being divisible
> by 60, you can combine it with the approach explained by Aaron at Wolfire (
> http://forums.wolfire.com/viewtopic.php?f=1&t=16539). In short, it makes
> every first and second frame take 17 milliseconds, and every third frame 16
> milliseconds. Personally, I combined all of that with what Disch explained
> at NESDev (http://forums.nesdev.com/viewtopic.php?f=3&t=6107) to try to
> mitigate SDL_Delay's unreliability.
>
> The second approach is to have your program wait for vsync after rendering
> a frame. To use this, pass the SDL_RENDERER_PRESENTVSYNC flag to
> SDL_CreateRenderer's flags parameter.
>
>
>
> Timers... pending subject. I'll start with them.
>
> I tried enabling Vsync before reading your suggestion. The scroll is smooth,
> perfect. Although I don't want to use this, because it limits the frame
> rate to the monitor refresh (60Hz in my case), and for this simple example
> is ok but for more complex processing can be a big limitation. Anyway I
> don't know much about game development to see if this can be or not an
> issue for a real 2D game.
>
> I found many examples claiming "smooth" scrolls but 99% of them use VSync.
> Few days ago I found 1 example with a very smooth scroll without using
> Vsync. This example (http://olofson.net/download/smoothscroll-1.1.tar.gz)
> uses SDL1 or GL (selectable), and a "time filter" to deal with shedulling
> jitter.
> The example shows a very smooth scroll with a map bigger than screen (in
> fact it's a parallax scroll of 3 layers).
> It comes with a precompiled example. The example works nicely. I compiled
> the source in VS2013, and... tadaaaaa with the new compiled code the scroll
> is not smooth [image: Crying or Very sad]
>
> I have to explore this, because makes no sense unless something is
> happening related to my especific hardware (I'm using a laptop). Again from
> my novice perspective a simple smooth scrool shouldn't be so hard, but it
> looks it is a challenge (of course without using Vsync).
>
>
>
>
>
> Jonny D wrote:
>
>
> If you have a low rate of scrolling, like on the order of 10 pixels per
> second or less, you will experience pixel-sized jitter.
>
>
>
> Yep, I was reading indirectly about that, when people use floats for
> calculating speeds and positioning what is correct then rendering with
> floats results and weird things happened.
>
>
> I'll try all your suggestions (and read the websites you posted), and will
> return with the results. I don't want to use Vsyng. If anyone has more to
> say, don't hesitate, I'll read the forum often.
>
>
> ------------------------------
>
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>
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