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#226 | ||
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Unknown.
Join Date: Aug 2002
Location: UK
Posts: 4,882
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Seriously though, never heard of Depth Clamping. Uttar |
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#227 |
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Trollipop
Join Date: May 2003
Location: Australia
Posts: 1,630
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Saw a diagram of the damn thing somewhere after the FX came out and serious it looked like a far clipping plane for shadows calculations ( the geometry is till used in everything else so its not quite a far clipping plane ).
Okay contacting my uber secret nvidia source I found out about the ultrashadow details. 1. They can do shadow volumes it in 1 pass rather then 2 which everyone else needed at that point in time supposedly ( I'm surprised R300 couldn't :/ ) 2. They use some of the info to cull pixles 3. Allows a DEVELOPER ( ie can't be done automatically on previous gen games ) to specify a z-min and z-max for that shadow which then allows the card/drivers to cull some parts of the scene ( man this diagram I got from their website sucks the "fill saving" looks to include the rendered scene rather then the stuff culled ). If you didn't guess the uber secret source is http://www.nvidia.com/object/LO_20030508_6927.html.
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Trolls find me soo tastey :P |
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#228 | |||
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Join Date: Feb 2002
Posts: 632
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#229 | |
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Junior Member
Join Date: Oct 2002
Posts: 26
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It would probably be difficult to design a Dx9 gfx-card that didn´t beat a Gf FX in that situation. Personally I doubt people will buy XGI gfx cards. There´s no reason if you can buy a much better ATI 9800 for the same money. And Nvidia, even if they are slow in Dx9, still has a good reputation among ordinary ignorant people. People that will continue to buy Nvidia cards. And the drivers could be a problem for XGI. Perhaps there will be problems with a lot of games. They are new and that could be expected. So my guess is that XGI will be nr:2 in Dx9 performance but few will buy the cards. |
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#230 |
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Junior Member
Join Date: Jan 2003
Location: Chile
Posts: 40
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from an overclockers.com poll, by Ed Stroligo - 11/3/03:
". . .Over 90% of those indicating they wanted a video card said they wanted an ATI card. There were a few who indicated nVidia, very few. Most who chose ATI didn't even mention nVidia as a factor. It's a wipeout for nVidia among this audience . . ." " . . . nVidia is quite another matter. This audience has proven in the past to be a good leading indicator of future trends for the general computing population, what they think today is often what others think tomorrow. I'd be scared excrementless if I were nVidia after seeing these responses. Right now, they aren't losing, they're not even playing, at least not according to this audience . . . " I entirely agree with that vision. If you look at polls in web sites at least 90% of last generation cards owned are ATI (both performance or value cards); Nvidia CEO says that video cards are not the main interest of Nvidia now. "Market share" quotes are just quotes from what remains of the past, I think what is selling now is much different. |
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#231 | |
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Off-season
Join Date: Feb 2002
Location: On the pursuit of happiness
Posts: 3,019
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Two-sided stencil doesn't save fillrate. It allows you to submit the geometry only once instead of twice, which saves bandwidth and VS performance. As for depth clamp and depth bounds: Depth clamp disables near and far plane clipping and allows you to define a range [zmin, zmax] to which the screen-space depth will be clamped. This way you don't have to worry about shadow volumes that extend past the near or far clipping planes. You don't have to generate extra geometry to "close" the shadow volume at the clipping planes. Depth bounds (UltraShadow) is a way to save fillrate/bandwidth while rendering stencil shadows. It simply acts on the fact that a shadow volume can't affect fragments that are in completely in front of it or behind it. So you define a range [zmin, zmax] in which the shadow volume fits completely. The chip can then discard any fragments where the depth value in the Z-buffer is outside this range. With a hierarchical Z-buffer, this rejection can happen per tile.
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Binary prefixes for bits and bytes |
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#232 | ||
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Senior Member
Join Date: Jul 2002
Location: BelleVue Sanatorium, Billary, NY. Patient privileges: Internet access
Posts: 2,694
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You make what seems to me a very odd distinction here between what nVidia releases as "information" which is "PR-centric" and "specific information" which I assume you mean is information which you consider technically correct and PR-neutral. My question to you is simply how can you distinguish which is which?.... Case in point: TR asked nVidia point blank a few months ago to clear up the confusion it had created around nV3x with the following question: "Does nv3x render 8 pixels per clock?" To which nVidia replied, "Yes, we do 8 ops per clock." (That was a line I doubt I'll ever forget.) Considering that nVidia was unable to provide a straight, PR-neutral answer to such a simple, fundamental question about its architecture as "How many pixels per clock does it render?", I find it difficult to believe the company when it discusses much more complex and arcane "facts" about its architecture. Obviously, I do not possess your ability to separate the wheat from the chaff in this regard... I mean, I find it just ludicrous that anyone might have to be "told" by ATi that ATi does generic, global shader optimizations in its drivers, before they might appreciate that ATi has in fact done this. Since the first 3d card shipped IHVs have routinely "optimized" their drivers in a global sense to get more from their hardware. I think DaveB was being polite to Josh with these statements, but really these are things that if one doesn't understand one has no business writing "state of 3d" articles, to put it bluntly. It doesn't follow for me that ATi should have to "talk about it" as nVidia has "talked about it" in order for me to consider it has been done. It's clear from using R3x0 for the last year that such things have been done, routinely. Rather, this is the kind of thing I expect them not to spend an appreciable amount of time talking about because it's just so evident in the performance and IQ of their products. So why isn't ATi telling us about such things? Because they are so self-evident, of course. At least, to me they always have been. I think it is illogical to assume that because nVidia talks about something that it is in fact what nVidia has actually done, or that because ATi has not talked about something that ATi has not done it. I have a problem with that approach. It's simply not required that ATi tell me about every little thing they've done in order for me to see that those things have been done, and indeed, when I contrast the deficiencies of nV3x with R3x0 I can understand why nVidia has done so much talking... What I have seen, though, demonstrated many times over the last year, is that there is often a gulf between what nV3x actually does and what nVidia PR says it does. In line with this disparity, people postulate all kinds of artificial constructs in an attempt to bridge the gap--and often come up with ideas which, while sounding plausible, cannot be verified or demonstrated by anything nVidia has actually said. I suppose that people do this because they cannot accept the fact that nVidia is simply misrepresenting its products--so they rationalize in order to avoid that conclusion. Let's take the whole, "DX9 is an ATi-Microsoft conspiracy with nVidia as its target," line of thought. Well, that's certainly one way to look at it... The last reminds me of the old saw about two guys each bidding their rocket designs to boost payload into orbit. One guy's design is 2 stages and costs $x, while the other's is 10 stages and costs $2.5x.... All talking seems therefore very much beside the point to me. I don't think we need a "monkey see, monkey do" situation where if nVidia talks about something it considers relevant ATi must address the same subjects, or vice-versa. The companies are different as are their products, and when we let the products do the talking we are left with some fairly clear and unambiguous answers. |
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#233 | |
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Member
Join Date: Feb 2002
Posts: 632
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#234 | ||||||||
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Senior Member
Join Date: Feb 2002
Location: CT
Posts: 2,024
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I said "specific information" in reference to both ATI and nVidia. I then referred to PR-centric and technically distorted in association with nVidia, because nVidia quite often seems to fit that with their information. Where is there a mystery of whether "specific information" is PR-centric or not...if it is, it seems for this discussion I'll be adding the description: "PR-centric" as applicable, as well as other descriptions that don't make "specific information" any more confusing. Are you confusing yourself by simplifying the situation to "acting like your opinion of nVidia wrong-doing" and "acting unlike nVidia in any arbitrary particulars that suit you", such that specific information has to be like the former? Quote:
It is also besides the point, since the problem Wavey seems to be referring to is the large amount of people who don't "distinguish which is which", especially those that publish. At least for the understanding I have of it, and agree with. Quote:
My arguing that there is a reason doesn't mean that I'm arguing that it is a good reason to confuse "plausability without factuality" with "factuality" (rather the opposite would be what I maintained...if we were to actually discuss the matter). It means that I'm suggesting ATI providing facts doesn't require more reason than what Dave mentions, because your viewing things as either "providing information like the bad information nVidia has provided" or "not providing information", doesn't mean things are actually that simple, even if you spend several paragraphs failing to relate that premise to logic. Quote:
Nevermind any mention of how "otherwise" is demonstrably the case, when you can take the opportunity to focus on how the issue is how they should avoid being nVidia instead? No, it is not obvious that ATI does generic global shader optimizations for your (lack of) stated logic, because it is obvious that generic global shader optimizations don't write themselves. A bit of logic: it would only require that ATI didn't write one. Given the 3dmark 03 GT 4 "valid optimization implemented other than generically and globally", not "knowing" that there was a generic and global optimizer doesn't seem too unreasonable. This wouldn't mean it would be ATI's fault that someone echoes what their competitors say about ATI's hardware and drivers without checking with ATI, it just means ATI can do something to improve the situation resulting from some people displaying such behavior (those people willing to listen)...without having to be exactly like nVidia. Quote:
Of all the things done wrong, not being born with the knowledge of the specifics of ATI's optimization is not one of them. It appears to me that you are transforming "that is wrong for that reason" to "that is wrong for this reason", where "this reason" is a new simplification whose apparent merit, so far, is to make it more convenient for you to propose your preference as some sort of divine mandate independent of logic. Quote:
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I actually have to wonder if you're trying to sabotage the idea of criticizing Josh, because this sentiment seems more suited as a satire of the idea that a writer should have a sufficient set of standards for checking and evaluating information. Why should they bother, if they should simply know everything to begin with? |
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#235 | |
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Member
Join Date: Mar 2003
Location: Denmark
Posts: 867
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http://oss.sgi.com/projects/ogl-samp...epth_clamp.txt Edit: Sorry I missed that Stevem allready has linked this file. |
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#236 | |||||||||||||||||
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Senior Member
Join Date: Jul 2002
Location: BelleVue Sanatorium, Billary, NY. Patient privileges: Internet access
Posts: 2,694
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My comments were also about the media, D... But, you asked me to explain my comments in connection with Dave's. In my first post, I quoted DaveB's comments verbatim, and in my response to your question, I quoted them again--just so there'd be no misunderstanding as to what I was responding to. Dave's comments that I quoted distinctly reference ATi's global shader optimization, and the comments I quoted do not mention stencils, which is why I did not talk about stencils. For some reason you keep wanting to overlook the comments I quoted and responded to, and make reference instead to comments I did not quote or respond to. I know that you think DaveB's comments didn't actually mean what they said as quoted, but I obviously disagree. This is getting silly, don't you think? "What I think I know," is irrelevant--I was quoting what DaveB said, and simply offering my opinions on issues that I see directly relate to them. Please don't tell me I have to quote those remarks a third time before you understand that what I responded to and what you think I should have responded to are two different things... Quote:
My point was that in these very forums I've seen people take nVidia's PR descriptions of its products and attempt to reconcile them with objective testing done on those products, and in the process create pages of meaningless speculation. Remember the "zixels" discussions? That's a prime example of how being in these forums does not serve as innoculation against nVidia's PR-centric technical "information" such as, "Yes, we do 8 ops per clock," when the company was simply asked to disclose the number of *pixels* per clock nV3x does. "Information" such as that coming out of nVidia has prompted many a marathon speculation session around here--not to be confused with discussions of any facts in evidence... Quote:
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Yes--that was my point exactly--that it takes more than plausibility to establish a fact. Quote:
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Again, my point was that I have no complaints with the information ATi has provided thus far. I really think it's stretching probablity to imagine that if even they did provide a longer list of factoids that those nuggets of information would either be completely understood or correctly placed in context. I don't think that they would be (obviously.) My point with reference to nVidia's "information" proves itself. Even when such "information" is provided it is more often than not moved completely out of context and/or completely misunderstood. And that happens because the basic assumption used in interpreting the information is flawed--that assumption being that the information is both accurate and correct. Heh... Quote:
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OK, the context here is about people publishing articles on "the state of 3d", and what such people should know without having to have it spelled out for them. When people write such articles they place themselves in the role of being an "authority figure" on the subject--ergo, they should know a lot of things without expressly having to be told about them afresh whenever they occur. Although I don't publish such articles, I didn't have to be told that ATi was globally optimizing for its hardware (shaders are no less "hardware" than anything else in the chip) to know that they were simply through empirical use of their products and the observations I've made stemming from that use, coupled with years of experience in the use of similar products. I would think that anyone setting himself up as an authority figure on 3d hardware to the extent of publishing articles on "the state of 3d" would be no less qualified. But to provide an example of what typically happens... ATi could say: "We, of course, do global optimizations in our drivers for our hardware, including shaders and everything else"... and some "authority figure" at a web site would undoubtedly interpret that as follows... "Well, out of ATi's own mouth we have it confirmed that ATi does application-specific optimization of its shader code...!" In fact, I think this has already happened more than once... So, the problem is not so much in the amount of "information" delivered, it's found in whether or not the information the IHV provides is first factual and accurate, but far more importantly the problem lies in the ability of those who hear it to understand it and to place it into meaningful context. And that's the real problem: some "authority figures" are illegitimate. If the information is false/highly misleading, they cannot see it; or if it is entirely factual they are unable to understand it and place it into its proper context. Quote:
Optimizing is a good thing. It's too bad that nVidia has succeeded in butchering the word over the last year, but unfortunately some people now see "optimizing" as some sort of "negative" when in fact it is common practice in the industry and has been for years. Secondly, I see no need to confuse application-specific optimization with global driver optimization, since they are entirely separate and I've not mentioned the former. Quote:
That's of course nonsense... So, again, the problem is not with the "information" provided by the IHVs, be it true or false, the problem is in the "hearers" of that information, and in their ability to understand whether it is truth or fiction, and to put all such information into its proper context. IMO, of course. Quote:
Nope, never said that. In fact, I haven't talked about application-specific optimization of any type. What I've said was that I didn't need to be told that ATi was doing global driver optimizations for its hardware, including its shader hardware, since this is what competitive IHVs *always* do, without question or exception. Discussing application-specific optimization is an entirely different subject, and I've not commented on it. Quote:
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#237 | |||||||||
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Senior Member
Join Date: Feb 2002
Location: CT
Posts: 2,024
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You, on the other hand, are talking about a fiction you made up of how ATI having a general and global shader optimizer is self-evident (again, please note that Wavey proposes that it was not the case for Cat 3.5 and earlier, and consider how non-omniscient people might have missed the change), as an excuse to argue against Wavey when he actually said "information". As I discussed, the idea is indeed a fiction, seemingly promoted by your ignorance of the possibility of how a "general and global shader instruction optimizer" is distinct from other optimizations IHVs may have already done, and continuing to miss how your basic premise is asserted to be completely incorrect by what you quoted. Quote:
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I look at the rest of your post, and I am (not so) amazed to note that you are also trying to dismiss a long history of discussions as useless because they bothered to discuss something you'd already made up your mind on (without any technical basis that seems evident). Strange, though, how you just proposed you wereonly talking about the shader optimizer a moment ago, and how this made my stencil example irrelevant. The "zixel" discussion wasn't meaningless, it was a discussion about some new information pertinent to NV3x performance, and how nVidia's PR was inaccurate in using "pixels". The very term "zixel" is a separation from nVidia PR, not something that follows it. I'm happy for you that you knew exactly the situation before the discussion, but, again, Wavey wasn't discussing your apparent omniscience. It would be...interesting...to go over (somewhere else) the topics you have complaint with, and how exactly you propose your discussion illustrates more "technical probity". While we're bringing up past discussions, I'll mention that I actually find your discussions to consistently be the exact opposite, most often ignoring technical details or even being downright technically incorrect. I believe I've even pointed it out to you exactly why on some occassions...though if you call those occassions "meaningless" I guess it's "obvious" that it doesn't matter? ... There is...quite a bit more I could say to try and decipher the multi-layered illogic and filibuster you present and illustrate the problems with it, and I'm sure it could be entertaining to some, but I think I've covered everything actually remotely on topic about your commentary. I am amazed at how little relation your conversation has to anything remotely established outside of what you've already decided without any apparent adherence to objective rationale at all. |
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#238 | |
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Dangerously Mirthful
Join Date: Feb 2002
Location: Winfield, IN USA
Posts: 15,314
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Elite Bastards - Adminish “Be polite, be professional, but have a plan to kill everybody you meet.” - General James N. Mattis |
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