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Prims bigger than 10 meters generate lag as the megaprims?


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The old "mega's cause lag" tale.   LL has increased prim sizes up to 64m from 10m now to accommodate the use of mesh objects and you can use them for regular building without issues or concern.

All current Mega prims as available on SL are fine and do "not" cause any additional lag whatsoever.. in fact, somewhat the opposite is the reality of it.    One prim of 60mx10m  pushes out the same data as a single 10x10 prim  six 10x10 prims linked together push 6x the geometry (6x the number of faces/sides to send) & vertice's that a single 60x10 will. 

Why are people thinking Mega's cause lag:  That's easy to answer but wives tales abound.  The reality of it, when Mega's first appeared on SL was many moons ago and created via a small hack (open capability left by Linden Labs actually) by Gene Replacement.  At the time they were created, there was no issues with them either, other than upsetting the LL price-per-prim cost model.  As time continued and things evolved, certain parameters of prims and some of the related code changed...  This code is generally coined as "Legacy Prim Code" where the old style prims had a few extra things you could do to them which are no longer available in SL.  This is where the "Mega's cause Lag" issue first became genuinely noticeable.   The old Mega's created by Gene are based on Legacy Prim Code which has a deleterious effect on the physics engine therefore causing what appears to be lag as that code is being attempted to be resolved by the LL Servers (the server's no longer have Legacy Prim Support code, just stubs to prevent breakage of existing historical content).

A few will argue this point but bear in mind that very few people out there do know the code and the issues and that most will only repeat the old tales of woe from the bygone era.


 

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No, they won't cause more lag.

What made the original megaprims a lag problem was a combination of several things:

The original megaprims actually only existed in a dozen of so sizes, but there were 200+ common variations created by using cut, slice, dimple and other 'prim torture' to reduce a larger size to something more usable. Calculating the actual surface positions of 'tortured' prims does add to lag, regardless of their size. But a prim made with the new 64 M limits in place doesn't need to be warped like that to make it a useful size, and so the calculations are much simpler, where the bounding box and surfaces agree.

Havoc 1 didn't deal well with physics calculations for prims over 10 M in size. Even if the prim wasn't physical, colliding with a large prim, with an avatar, including walking on it, caused calculation problems. This was made even worse if the prim being collided with was a 'tortured' shape, because it had to calculate the effective surface positions too. We are on Havok 4 now, which deals with larger prim sizes much better.

FYI - I am one of the people who created a lot of the "second generation" megaprims, when a new server glitch 4+ years back enabled us to make new megaprim sizes, based on the current prim code, in a large range of sizes that didn't need prim torture to be useful. So for example if you use a 1M x 100M x 0.1 M megaprim made in that era, and don't force it to change apparent size with prim torture, it's no worse under Havok 4 than any other prim.

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