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Old 12-29-2010, 02:21 AM
Heliocon Heliocon is offline
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Quote:
Originally Posted by The Kraken View Post
Actually what you describe is using tesselation for continuous LODs in contrast to distinct LODs, which is the classic technique; but let's skip the semantics...



True but irrelevant as long as distinct LOD models are still needed for users without tesselation-capable cards. Also making a model purely out of primitives and surface maps is a nightmare, and that would be required if tesselation is supposed to provide continuous LODs.



RAM is cheap these days, even on the GPU, and tesselation does require memory for its data as well. The difference is insignificant. Popups can definitely be an issue with distinct LODs, but that's again a quality and not a performance issue.

You previously said the game would be "badly coded" when not using tesselation, and that without it all planes would have to be rendered at full quality all the time. That's why the standard LOD approach was brought up, and as it doesn't come with an additional calculation overhead, can make use of geometry instancing for much improved performance, is perfectly compatible with GPUs from several generations and vendors and doesn't need a completely new modeling approach, it certainly looks like the better solution at the moment. Nobody is against tesselation as such, but right now the technology simply isn't mature and widespread enough.
Yep you are correct, the example I used for the tesselation was used due to people saying tesselation does not give better performance for quality then non tessalated models with the same details. Thats why I phrased it the way I did, of course they use LOD but I was trying to explain why tessalation delivers great quality with less performance hits then if it was all high polygon count models. Also LOD has to store all the textures etc (minor stuff), but for high res gaming how many different models do you think they will use/need? What looks like a smooth hull at 50m looks like a octagon at 10m...

Like said though from what I have "heard (as I have never worked wit tesselation or that type of 3d graphics) it should be very easy to convert the models for tesselation (says Nvidia). But going from that you only need 1 model which auto scales. Reason I am advocating for it is because DX9 and DX10 have hit the end of their lives. Windows will no longer support xp in 2011 (I believe, dont know which month it official stops) and vista soon after. DX10 was horribly but Win 7 / DX11 is where everyone is going to, check out steams statistics on users hardware. Win7 64 bit is already the most common, and with the new second gen dx11 cards these graphical effects are the bread and butter of the coming (well actually this) generation.
I am not sure though about LOD and its interaction with lighting vs tesselation over various distances. One thing we havent touched on is the terrain (not planes or buildings). Maybe it would be better used on the ground due to the nature of the geometry (nothing than having a line in your vision where trees suddenly "appear" etc.

Last edited by Heliocon; 12-29-2010 at 02:27 AM.
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