Wobbly Mob

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ID:84818
 
Oct 30 2009, 2:26 pm (Edited on Sep 2 2010, 7:46 pm)
Resolved
When using gliding, the client eye could get out of sync with the mob during stop-and-go movement even when simply leaving the default settings alone, as long as glide_size was not specified.
BYOND Version:454
Operating System:Windows XP Home
Web Browser:Opera 10.01
Applies to:Dream Seeker
Status: Resolved (494)
This issue has been resolved.
Descriptive Problem Summary:
It seems that the client's mob doesn't like to stay within the bounds of it's tile. When moving, it likes to "wobble" around.

Numbered Steps to Reproduce Problem:
Download this demo; walk around. Mashing the arrow keys helps. This demo has screen objects around the mob to highlight the fact that the mob wobbles. Note that you should not see any of the blue turfs between the red and green, as the green is the mob and the red are stationary screen objects.

Here is the source:
turf
    icon = 'blue.dmi'

obj
    screen
        icon = 'red.dmi'

        New(client/C,X,Y)
            screen_loc = "[X],[Y]"
            C.screen += src
            ..()

mob
    icon = 'green.dmi'

    Login()
        new/obj/screen(client,5,5)
        new/obj/screen(client,5,6)
        new/obj/screen(client,5,7)
        new/obj/screen(client,6,5)
        new/obj/screen(client,6,7)
        new/obj/screen(client,7,5)
        new/obj/screen(client,7,6)
        new/obj/screen(client,7,7)
        ..()


Expected Results:
To move, seamlessly, from tile to tile.

Actual Results:
Wobbly movement. If you'll notice while moving in the demo, you can see a bit of blue between the red and the green. If the movement was working correctly, this should not happen.

Does the problem occur:
Every time? Or how often? All the time.
In other games? I don't play games, so I'm not sure.
In other user accounts? Yes.
On other computers? Yes.

When does the problem NOT occur?
I haven't noticed it not occurring.

Did the problem NOT occur in any earlier versions? If so, what was the last version that worked?
I believe it started happening right after the movement updates. I don't remember which version it was. It was somewhere around 440, I believe.
Oct 31 2009, 8:40 am
Can you be more specific on what you're seeing? I've never noticed any "wobbling" before, so it'd help to have an in-depth description of the problem.
Oct 31 2009, 9:22 am
I think I see what he means; sometimes when going one direction continuously, the red block tends to move a little off-center from the green canvas surrounding it, revealing a little bit of the blue turfs underneath the red block
Nov 1 2009, 6:56 am
Yeah, I'm not sure what "wobbling" means. Maybe if you changed the color of the green square and the teal lines would help?
Nov 1 2009, 7:43 am
Photobucket
Nov 2 2009, 8:20 am
I still don't understand the circumstances behind this bug. Providing a .dmb-only example is not particularly helpful because it doesn't give me any idea what methods you're using for the movement. There is also still no detailed description as requested. I can confirm what you're seeing in the .dmb, but you have not yet given me the info to find out if that's a normal result or an actual bug.
Nov 2 2009, 8:37 am
Lummox JR:
Providing a .dmb-only example is not particularly helpful because it doesn't give me any idea what methods you're using for the movement.

None. That was the point; I have not modified Move() at all. Here are the details that I have left out.

Blue = Turf
Red = Mob
Green = Screen Object

If you would still like the source, I can post it when I get home later. But honestly, what could I possibly be doing for this to be a normal result?
Nov 2 2009, 8:49 am
This happens in every game I've played on BYOND, although it didn't happen some time in the past, but I can't remember in which version it started occuring, it was too long ago.

But to me it seems that it's rather the client eye sometimes "can't keep up with the mob", rather than the mob itself wobbling. The client eye seems to "shake" mildly
Nov 2 2009, 8:57 am
Hiro the Dragon King wrote:
None. That was the point; I have not modified Move() at all. Here are the details that I have left out.

Blue = Turf
Red = Mob
Green = Screen Object

Those are rather important details, as it happens. This is why it is always essential to include as much information as possible with your bug report. Your initial report was very vague.

If you would still like the source, I can post it when I get home later. But honestly, what could I possibly be doing for this to be a normal result?

Well for starters, it is not reasonable to assume that server-driven changes to a screen objects (HUDs that is, assuming we're on the same page with the terminology) are going to sync up fully with client-side gliding of a regular object. If this is really the case then there is no bug.

But regardless it is important to produce a demo with source whenever possible, because being able to see what should happen based on the source, and possibly trace the specific DM commands responsible, is often the difference between finding the cause of a bug or not.
Nov 2 2009, 9:04 am (Edited on Nov 2 2009, 9:12 am)
Oh and I've experimented a little and, this "wobbly" effect does not seem to occur at very low tick lags.

At tick_lag 0.2 it doesn't happen at all it seems
Nov 2 2009, 9:28 am
Nielz, if you see an issue like this then it probably belongs in a separate bug report, with a demo. Based on Hiro's information it's likely to be a completely different cause.
Nov 2 2009, 9:36 am
Lummox JR wrote:
Nielz, if you see an issue like this then it probably belongs in a separate bug report, with a demo. Based on Hiro's information it's likely to be a completely different cause.

I don't want to doubt anything you say, but I am absolutely certain that it's the same glitch, if it can be called a glitch

As I've said in comment #9, this "wobbly" effect as Hiro calls it, happens in every game I've played on BYOND

Nov 2 2009, 10:19 am
Nielz, just because you're seeing the same kind of thing doesn't mean it's the same cause. The conditions Hiro briefly mentioned wouldn't be happening in every game in BYOND, hence it is not the same thing even if the results are similar.

I'm on the cusp of marking this "Not a bug" pending a real demo from Hiro, but the same result coming up in some other scenarios could be a real bug and would warrant a separate report--with a demo to reproduce the problem.
Nov 2 2009, 11:16 am
Lummox JR:
The conditions Hiro briefly mentioned wouldn't be happening in every game in BYOND, hence it is not the same thing even if the results are similar. ... --with a demo to reproduce the problem.

I mentioned no conditions... Furthermore, the demo doesn't reproduce the problem, it merely accentuates it. So far as I can see, it is always there.

I have updated the Bug Report. The source doesn't show anything I haven't already mentioned. The only reason I didn't post the source was because I thought that it was simple enough to be excluded, read, I was rushing.

The mob should stay perfectly still in the center of the screen; it doesn't. It wobbles, i.e., it moves back and forth a few pixels. The screen objects are simply there to accentuate this. You shouldn't be able to see any blue between the red and green.

The screen doesn't move improperly. Screen objects don't move improperly. The mob is the only thing that is moving -wrong-.

Edit: I will not rush further reports as to avoid this in the future.
Nov 2 2009, 11:52 am
Hiro the Dragon King wrote:
I mentioned no conditions...

You said the green bits are screen objects, and the red is a mob.

Furthermore, the demo doesn't reproduce the problem, it merely accentuates it. So far as I can see, it is always there.

As I said originally, I haven't seen "wobbling" in other projects so I need something a little more detailed to go on. Your file does reproduce the issue you reported.

Regarding this particular issue I think I see the problem that you mean though, in that the eye and the mob don't appear to be entirely in sync even though the mob is the eye. That's something I can investigate further now that I understand the cause.
Nov 3 2009, 7:54 pm
I realize that my original report was vague. I really, really don't want to attack (for lack of a better word, at the moment) you, because I do in fact have respect for you, but I have to point out some things. It is my nature to sound a bit snide, but I mean no disrespect.

Lummox JR:
The conditions Hiro briefly mentioned wouldn't be happening in every game in BYOND...

Myself:
I mentioned no conditions...

Lummox JR:
You said the green bits are screen objects...

These are not, to all intents and purposes, conditions. A condition is a restricting, limiting, or modifying circumstance, i.e., "it can happen only under certain conditions." I have earlier mentioned, twice, that the screen objects were simply there to accentuate the problem, read, the problem happens whether or not they ar present but they help to make the bug "stick out." Thus, they are not a condition.

Lummox JR:
...and the red is a mob.

The fact that I am using a mob, or that the mob is a red square is not a condition under these circumstances because without a mob, there wouldn't be a visual system by which to have such a bug.

This is not to mention, 99% of the games on BYOND use a mob and most that I have seen, use screen objects.
Sep 2 2010, 7:43 pm
Not to be any more of an ass than I already have in this report, but this issue is still ugly and still annoying. Any chance of a second look?

P.S. I edited the initial report to be a bit less vague.
Sep 3 2010, 12:59 pm
Unfortunately the new information isn't really new; the issue is still confirmed, but highly difficult to fix.
Sep 6 2010, 3:39 pm
I didn't add anything new, I only edited it to be more specific to new readers. Anyway, that's a shame. Not that I use mobs that often anyways.
Feb 4 2011, 2:03 pm
Bump. This is still a rather annoying bug. As much as I was an ass last year and I'd like to not sound like one now, I was wondering about the status of this bug. Smooth transitions from tile to tile in the default movement engine seems like a rather important issue to me.
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