Dreaded Drift

Hello all,
I ll assume for the purposes of courtesy that everyone is just dandy today.....that is, except me, oh no, dandy I am not, primdrift fury I am.

So has anyone out there in the big ol bad ol SLuniverse any real world practical answer to the problem of prim drift? And I dont mean a technical description of what it is ( I know it is a floating point error), I mean a way to compensate for it other than obsessively and indeed compulsively checking and re -aligning each bloody prim I make every single hour?


I have dined, hearty at the table of the horsemen.

It seems after last update not only prim drift, but also prim params arent stable. I think this have something to do with memory leaks after introducing flexiprims and light sources. They didn't update positions of various parameters in memory, but added some new, so now some parameters are overwriting others.

Sweet merciful heaven. Please somebody answer him - prim drift may be the death of me.

It is an extremly irritating phenomenon, so irritating that it is draining my will to build.

I have this beautiful Desert Palace you see, spent at least 150 hours on it meticulously aligning each piece, getting it ready for sale, highly detailed opulent and elegant....over 225 prims in total ( which is a marvel if you could see the resulting structure ), I have crafted and laid each individual object, placing it just so, then linking various sections.....diligently writing down each root prims' exact position( yes boys and girls I use a pen and, mercy me a piece of paper for this ) then saving it to my inventory, soothing my strained neck muscles and staving the pounding headache with a small cigarette, yes its a filthy habit......then I re rez each piece from inventory, place it exactly according to the measurements I have taken previously and lo, it is a mess of white seams and mis matched heights and weird angles.... I need someone to tell me there is a way to at least work around this...if not does anyone out there want to volunteer as a punchbag?


I have dined, hearty at the table of the horsemen.

Unfortunately, there's no good answer here. As you're aware, the problem has to do with math errors (or rounding discrepencies, or whatever you want to call them) within the system itself. There's not much that we as users can do to prevent that. All we can really do is deal with the problem as it arises, and try to correct for it. I usually put the offending prims back where they're supposed to be by hand, then shift-drag a new copy, and delete the originals. In my experience, after a prim drifts once, it will keep drifting, requiring constant maintenance to keep it place, but new copies seem to be much more stable.

This is a snap of Damen's beautiful palace, i so hope he doesn't give up on building. This is only his 3rd building project.

http://adam-n-eve.blogspot.com/

Lets take up our arms and band together, well not literally as we 'd be halfway from here to Tuvalu if we linked inworld what with the drifting and such.

This issue seems to have been around for quite some time now, for instance I have noticed posts around 2003 regarding it and the problem still hasnt been addressed.

My thinking is a mass HELP>REPORT BUG " I have stinking prim drift issues, any chance of fixing it before I go clinically insane " message to the Lindens, or has this been done before?

Thank you Chosen for your advice, I will implement it through gritted teeth and with the aid of my filthy habit.

I have dined, hearty at the table of the horsemen.

I made a 2700 prims pagoda and it's been on SupportforHealing island for more than a month now, not one prim has drifted since. Never saw this phenomenon in any of my builds. Could this have anything to do with lost packets?

I've noticed that if I don't use the maximum size on prims, it happens less. I can't confirm this since its based on experience only. Seems that 10m x 10m prims are the worse culprits.

IEEE floats are stored as 32 bit numbers, with a mantissa of 23 bit (1 implied), a mantissa sign, and an exponent of 8 bits.
See http://en.wikipedia.org/wiki/IEEE_floating-point_standard

The max size of a mantissa is 8 million, so it should be good for at least 6 decimal digits. However, it is a binary representation, so there may be conversion errors. Some discussion of that in http://www.codeguru.com/forum/printthread.php?t=323835.

But when you look at some real numbers, like 10.00, 9.99 and 9.98, they are separated by the minimal prim size and I suspect that the lindens have done some bit stuffing so that they can store these numbers in less space on their asses server. IEEE rounding errors should only show up in the 6th or 7th digit, and prim drift is on a much more significant scale than that. Combine that with software updating, and you have a recipe for disaster.

We really need to have LL come out and say that this is not the case. Furthermore, it should be trying to solve this real problem. It is these sort of problems that will stop SL from being considered a serious platform.

Ed

I wonder what causes it, too, because I also have never seen this phenomenon.

I get snapback a lot. and also spontaneous unlinking (when I've rotated a linked piece).

But thankfully never prim drift. It can't be height that's causing it. at least not within the normal 768 range because I have a huge build between 650 and 750m that's been stable for more than 2 months.