_xxx_ said:Didn't know about GFFX supporting it though. I suppose it was slow as a**, maybe just somehow emulated in SW?
No it was in hardware and was one of the major reasons for NV30's lackluster performance IIRC.
_xxx_ said:Didn't know about GFFX supporting it though. I suppose it was slow as a**, maybe just somehow emulated in SW?
geo said:Edit: Inq broke the existance of this new benchmark here: http://www.theinquirer.net/default.aspx?article=31799 So I think it reasonable to assume Faud has been in contact with them for some time.
trinibwoy said:Yeah I can see that perspective. But would you really like to set that precedent for a publication like the Inquirer that trades in conspiracy and rumor? As a PR manager reading that Inquirer piece what would your reaction be? Would you really want to validate that drivel with a response?
Maybe because you didn't read the first reply to this thread?The Baron said:"NVIDIA cards are locked at FP16 lawls!" Er, I get the feeling that given today's shader-intensive games, we'd be able to, y'know, see rampant artifacting in just about any screenshot when it was compared to an X1900 screenshot. Why am I the first person to think of this?
You recall incorrectly. NV30's lackluster performance was primarily due to:trinibwoy said:No it was in hardware and was one of the major reasons for NV30's lackluster performance IIRC.
Don't forget the free FP16 normalize...Jawed said:A fair way down this long page (3/4) you can see that FP16 still has the potential to make a massive performance difference with G71:
http://www.digit-life.com/articles2/video/g71-part2.html
in the: Cook-Torrance, Parallax Mapping and Frozen Glass shaders, the latter two regardless of the use of the arithmetic- or texturing-intensive versions of the shaders.
That article is a few months old now, but at least indicates that the driver wasn't forcing _PP on the code being executed.
Which I think was the heart of the problem with ambient lighting in D3, wasn't it?MDolenc said:Don't forget the free FP16 normalize...
Jawed said:It wouldn't be computationally expensive to make the driver force _PP on ALL instructions. Don't forget that shader code is always "compiled" by the driver in realtime, anyway.
I can see a case for hypothesising that the driver does indeed force _PP - NVidia's driver team can then create game profiles that identify exceptions - or provide explicit shader code to be substituted (i.e. mixed _PP and normal precision).
But the iXBT/Digit-Life evidence implies that if there is driver-forcing, it's new.
That doesn't mean that FP16 normalize is broken or doesn't have enough precision. It says clearly "That works on all surfaces except ambient ones where our cubemap isn't a normal cube map." FP32 normalize would also broke that simply becouse normalization cubemap was not a normalization cubemap.Jawed said:Which I think was the heart of the problem with ambient lighting in D3, wasn't it?
NVidia was forcing the free FP16 normalise (shader replacement) in preference to a cubemap lookup.
http://www.beyond3d.com/forum/showthread.php?t=23195
Jawed
Well, while it might be possible, I doubt that nVidia would ever do it, because it would significantly lengthen shader compile time. Modern games use a very large number of shaders, making shader compile time somewhat important.geo said:The below is only tangentially involved with whatever it is (still unclear) Inq is pointing at. I'm not suggesting this is what's happening. Particularly given Jawed's excellent point showing that full precision is still biting G71 in spots. Automating _pp has just always been a fascination of mine.
We know NV has had three years to push around _pp. I wonder if it might be technically doable with some extended effort over that time to come up with an automated algo in the driver to reliably predict (> 95%) some subset of shaders that could be forced to _pp? If a shader fails whatever your algo is looking for you leave it alone. That's key. The "reliably predict" part is just so far as being accurate when the algo *does* decide this particular shader can safely be _pp'ed. Then the question would be what percentage of shaders it is finding it can do that with.
Chalnoth said:Well, while it might be possible, I doubt that nVidia would ever do it, because it would significantly lengthen shader compile time. Modern games use a very large number of shaders, making shader compile time somewhat important.
geo said:Well, this is why I mentioned multi-core cpu as a possible enabler.
Edit: Oh. I guess I never really thot of where this "compile" is happening. . .or rather old skewled myself into thinking it must be on the cpu . . .but I guess I really don't know that. Where are shader compiles done?