Unsure if RealXtend or if the RealXtend Dev group is the right place for this post but here goes.
One thing that has annoyed me for a long time in Second Life, that I do not have to deal with in game engines, is the lack of proper alpha test support, as well as high quality normal maps. I really believe some of this is due to the dependence on the JPG2000 format, and the desire for some reason, not to enable the ability to upload 1 bit alpha images - Linden Lab insists on doing this on the fly through file conversion instead, which often results in a lower quality product, not to mention JPG2000 is not an ideal format for compressing large areas of a single color. Is there any plans to add DXTC support, especially when it comes to DXT1 alpha and 3Dc format for normal maps? These are more ideally suited to the graphics card, even though JPG2000 is a better format for diffuse due to the savings in compression. I wrote up a JIRA request for this for the Second Life client (which I am sure will be ignored like just about all JIRA requests there do) but folks are welcome to read what I have posted there, so I offer it up as a topic for discussion. http://jira.secondlife.com/browse/VWR-20322 -- Second Life content creators use a heck of a lot of textures, and the lack of ability to really optimise textures, is really one of the major sources of lag in the viewer. JPG2000 is not a good algorithm for normal map creation (3Dc format is), nor is it really good for making alpha test textures (DXT1 is) - as evidenced by the fairly crappy automatic "fast alpha" that we see in SL and the lack of normal maps (aside from the water - but JPG2000 limitations are clearly seen there). We need more than JPG2000, as it has limitations that can be overcome by other formats. JPG2000 is good for regular textures, but we need better technology for alpha test (1 bit) textures and for the eventual use of normal maps, to improve the visual experience and frame rates inworld. DXT1 is ideally suitable for alphatest textures and is smaller than JPG2000, it is also supported by the graphics card natively. Additionally 3Dc format is much more optimised for normal maps. Links to further information on this topic for discussion: http://www.evl.uic.edu/files/pdf/ag2007-renambot.pdf http://developer.nvidia.com/object/texture_tools.html http://softwarecommunity.intel.com/UserFiles/en-us/Image/1221/Real-Time%20Texture%20Streaming%20&%20Decompression.pdf> read online http://cache-www.intel.com/cd/00/00/32/43/324337_324337.pdf and on normal maps: http://developer.nvidia.com/object/real-time-normal-map-dxt-compression.html >From the Intel/id Software document (third pdf) - "Although JPEG 2000 produces superior quality compared to JPEG, the gains are modest at medium compression ratios (10:1). The improvement is typically much larger at higher compression ratios [5] but there may also be a noticeable loss in quality. JPEG 2000 eliminates some of the compression artifacts introduced by JPEG at higher compression ratios, such as blocking artifacts. However, JPEG 2000 can introduce quite prominent blurring and ringing artifacts. *Furthermore JPEG 2000 decompression is significantly more computationally expensive than JPEG decompression and requires more memory during decoding.*" -- In general I am very happy with the frame rates I get in the Naali viewer - they are way higher than framerates in Second Life and also significantly higher than framerates in the old RealXtend viewer - I am looking forward to seeing it more fully fleshed out in features. Also I am getting a bug in that alpha textured surfaces do not cast shadows for me, on either my Win7 x64 on an ATI HD 5770, or on my Vista x64 on a NVIDIA 8600 GTS, in either Naali or the old RealXtend viewer - is there any way to fix this? I havent experimented harder yet (maybe a plane needs to be two sided?) but the trees definitely are not casting shadows for me from the leaves. take care, -- hypatiaa -- http://groups.google.com/group/realxtend http://www.realxtend.org
