Re: [Algorithms] BSP tree, or what?

[Jamie F. <ja...@qu...>]

Stefan Sandberg wrote:
> I find that reasoning pretty silly..
> Wherever you gain performance(or rather, reduce cost), it's a win..

Only if it's a consistent win, or improves your worst case. If you gain 
performance in a situation which isn't your worst case (e.g. facing a 
wall), and lose performance in your worst case (e.g. viewing a large 
open area with many entities), I wouldn't call that a win. All occluder 
fusion code falls into that category for all situations I've seen; your 
situation may be different.

Jamie

> Naturally you cap your framerate at something, usually 30-60 fps, that 
> doesn't mean that you wont benefit from a solution that
> is capable of 4 times that framerate if you let it loose. Just spend 
> that time doing something else..
> Most graphics artists & designers would massage you daily if you told 
> them you figured out a way for them to
> have twice the amount of <something> in the game...
> 
> Megan Fox wrote:
>> While this is true, do keep in mind that occluder fusion isn't
>> necessarily going to win you anything you actually want.  Consider the
>> case where a collection of trees, viewed just so, occludes 80% of the
>> scene, netting you a significant performance boost.  This is a bad
>> thing, not a good thing - because players respond better to a
>> consistently mediocre framerate than they do to a framerate that
>> spikes massively and inconsistently.
>>
>> I'm all for occlusion where it makes sense (big city buildings, big
>> houses, large walls), but most of the places where occluders make
>> sense are probably also places where individual objects are big enough
>> to just be modelled with occluders built in - no need for fusion.  The
>> usual example of "and we can take this group of people / cars and
>> occlude everything behind it!" tends to be a plain bad idea, unless
>> you're in the unlikely situation of having a game in which you're
>> absolutely always surrounded by a mass of (something indistinct).
>>
>>   
>>> All of those mechanisms can be improved, from a rasterization point of
>>> view, by adding dynamic occluders (ideally with occluder fusion). I know
>>> that the IHVs say that their cards are efficient enough that you
>>> shouldn't bother, but that's only true for the "GTX" versions -- the
>>> 64-bit versions that end up in the laptops that most of the buying
>>> public are buying, are still very fill rate sensitive.
>>>
>>> Sincerely,
>>>
>>> jw

-- 

Jamie Fowlston
Program Manager
Tools & Technology
Qube Software

www.qubesoft.com