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Author Topic: Problem with choppy/laggy/jerky scrolling in SFML2 (binary inside)  (Read 6868 times)

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waxx

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Hi guys

I've been coding my next game - a runner - for couple of weeks and yet I can't seem to handle the problem I have with it. It runs like shit. Now, I don't believe I'm doing anything wrong performance wise, as simple one sprite scrolling slowly on screen feels choppy on its own. And in dynamic game like mine it really is annoying. I don't know what to do - in case it's only my weird feeling I'm throwing out here a test binary (controls: Z jump X attack), try it for yourself:
https://dl.dropbox.com/u/9649932/Release.rar

Looking forward to some feedback and tips.

eXpl0it3r

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Re: Problem with choppy/laggy/jerky scrolling in SFML2 (binary inside)
« Reply #1 on: January 19, 2013, 11:51:29 pm »
Looks nice! :)

It seems you've implemented a bad way to calculate the physics. You should take a look at this article.

But without code we can't really help you...
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waxx

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Re: Problem with choppy/laggy/jerky scrolling in SFML2 (binary inside)
« Reply #2 on: January 19, 2013, 11:53:55 pm »
Well... I'm basically not even using any delta time nor anything, capped FPS with VSync and left it like that. Should fixed timestep actually fix it?


eXpl0it3r

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Re: Problem with choppy/laggy/jerky scrolling in SFML2 (binary inside)
« Reply #3 on: January 20, 2013, 12:55:30 am »
Well... I'm basically not even using any delta time nor anything, capped FPS with VSync and left it like that.
Then you're doing something quite wrong in your calculations...
Also keep in mind that this can be quite a bit 'dangerous', because SFML can't guarantee that VSync gets activated, because one usually can force VSync on/off with the driver.

Should fixed timestep actually fix it?
Probably not, since it's a problem in your math (I guess), but it's better in any case. ;)
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waxx

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Re: Problem with choppy/laggy/jerky scrolling in SFML2 (binary inside)
« Reply #4 on: January 20, 2013, 08:17:00 am »
//pseudocode
speed = 0.05f;
pos -= speed;

drawAt(clouds, pos);

how's that my math's problem?? simple thing like this already makes the thing damn laggy

eXpl0it3r

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AW: Problem with choppy/laggy/jerky scrolling in SFML2 (binary inside)
« Reply #5 on: January 20, 2013, 09:31:04 am »
And again, without code we can only guess. ;)
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waxx

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Re: Problem with choppy/laggy/jerky scrolling in SFML2 (binary inside)
« Reply #6 on: January 20, 2013, 07:23:48 pm »
I just gave you the code.

eXpl0it3r

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Re: Problem with choppy/laggy/jerky scrolling in SFML2 (binary inside)
« Reply #7 on: January 20, 2013, 07:50:05 pm »
I just gave you the code.
Where? That little pseudo code you mean?
As you've noticed on your own, it 'probably' won't be the cause, thus we need to see a complete and minimal example that reproduces the problem. Which means that you have to narrow down the problem, while minimizing the codebase. If you do that you also don't have to fear any code 'stealing' or whatever are your reasons for not giving more information in the first place... ;)
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waxx

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Re: Problem with choppy/laggy/jerky scrolling in SFML2 (binary inside)
« Reply #8 on: January 21, 2013, 04:41:42 pm »
zzzzzzzz
#include <SFML/Graphics.hpp>

int main()
{
    sf::RenderWindow window(sf::VideoMode(1024, 600), "SFML works!? No");
        window.setVerticalSyncEnabled(true);
        sf::Vector2f pos(0,0);
        sf::Vector2f pos2(2048,0);
         sf::Texture img;
     img.loadFromFile( "test.png" );
         img.setSmooth( false );

    while (window.isOpen())
    {

        sf::Event event;
        while (window.pollEvent(event))
        {
            if (event.type == sf::Event::Closed)
                window.close();
        }
               
                pos.x -= 0.5f;
                pos2.x -= 0.5f;
               
                if(pos.x + 2048 < 0)
                        pos.x = pos2.x + 2048;
                if(pos2.x + 2048 < 0)
                        pos2.x = pos.x + 2048;

                sf::Sprite sr(img);
                sr.setPosition(pos);
               
                sf::Sprite sr2(img);
                sr2.setPosition(pos2);

                window.clear(sf::Color::Yellow);
        window.draw(sr);
        window.draw(sr2);
        window.display();
    }

    return 0;
}

Test asset: https://dl.dropbox.com/u/9649932/test.png
How to test: compile and run, stare at it literally for 30-60seconds, focus please, and tell me whether the movement is fluid and smooth as toddler's arse or choppy and jerky for whatever reason

cire

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Re: Problem with choppy/laggy/jerky scrolling in SFML2 (binary inside)
« Reply #9 on: January 21, 2013, 05:12:53 pm »
It is perfectly smooth here.

eXpl0it3r

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Re: Problem with choppy/laggy/jerky scrolling in SFML2 (binary inside)
« Reply #10 on: January 21, 2013, 05:20:18 pm »
Yep works fine here too, while the release binary has problems...

Have you ever run any performance test on your update function, is it at all time <= 1/60 of a second?
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waxx

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Re: Problem with choppy/laggy/jerky scrolling in SFML2 (binary inside)
« Reply #11 on: January 21, 2013, 06:54:02 pm »
But even the sample I just gave you feels meh to me. Are you guys running it with static or dynamic libs?
And my PC is high-end.

krzat

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Re: Problem with choppy/laggy/jerky scrolling in SFML2 (binary inside)
« Reply #12 on: January 21, 2013, 07:30:48 pm »
Disable vsync a try higher fps.
SFML.Utils - useful extensions for SFML.Net

eXpl0it3r

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Re: Problem with choppy/laggy/jerky scrolling in SFML2 (binary inside)
« Reply #13 on: January 21, 2013, 07:52:39 pm »
But even the sample I just gave you feels meh to me.
Well 'meh' isn't really something we can go with.
For me there's a huge difference between the release and the demo code, see here:

http://www.youtube.com/watch?v=hgT4siUPDNo
It's a bit harder to spot on the YouTube video itself, but one can still spot the stutter.
At 0:50 you get the demo application.

Are you guys running it with static or dynamic libs?
How would that have an effect?

And my PC is high-end.
This isn't a justification not to perform some tests... ;)
« Last Edit: January 21, 2013, 07:54:32 pm by eXpl0it3r »
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waxx

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Re: Problem with choppy/laggy/jerky scrolling in SFML2 (binary inside)
« Reply #14 on: January 21, 2013, 09:13:58 pm »
Oh well, maybe I tried to implement fixed timestep in a wrong and thus I implemented dt only, there might be a difference now.

https://dl.dropbox.com/u/9649932/Release.rar

Can you test it out on your end?