[sldev] Optimus Prim vs. Megatrim: "The Big Prim Problem"

[Dzonatas]

Argent Stonecutter wrote:
>> When you rez a prim larger than 10 meters, it gets ignored by the 
>> physics engine.
>
>> That would break content.
>
> Only if it was applied to existing megaprims. They obviously should be 
> grandfathered in for some period.

True, but there are some megaprims that are friendly and others that 
wreck Havok (and more).

>
>> On the rez event, instead, is where parts of the system can use the 
>> original untranformed/unoptimized version (hence "protoform") and 
>> decide if it can work well with the physics at that point or if it 
>> has to force phantom.
>
> So you'd have the same prim sometimes being treated as multiple prims 
> and sometimes not? Sometimes phantom or sometimes not?
>
> The thing is, as far as the physics engine is concerned, a linkset 40m 
> across is just as hard to deal with as a single prim 40m across. A 
> linkset with a hollow is just as bad as a hollow prim. If the prims 
> are unlinked and magic, what happens if some of them are deleted? It 
> seems a lot of complexity that will violate the principle of least 
> astonishment.

There is a parallelization process that could happen within a sim. The 
single 40m prim offers no parallelization ability by default by itself. 
A prim made of smaller prims may be broken up and processed by two (or 
more) separate render paths on the physics side. With both version 
available, one optimized megaprim could travel across a sim boundary and 
be handled physically by both.


>
>> Given both versions of transformed and protoforms, each process 
>> (client or server) can decide what is the best version to use. All 
>> the calculations to render either version can be done ahead of time 
>> instead of on each event.
>
> I don't see how exposing the complexity to the end user provides any 
> benefit. As something that the server could to to simplify the 
> calculations for concave objects under the hood, sure... but the 
> client doesn't care, it only wants the graphically simplest form.

It does not need to be exposed. The current state of the viewer would 
only have such exposure just to give the ability. Beyond that, the 
viewer can include (in the future) specialized megaprim builders (as 
sort-of suggested in Aimee's blog -- please review her blog again).


-- 
Power to Change the Void