On Mon, Jan 10, 2011 at 11:47 AM, Ricky <kf6...@gmail.com> wrote: > Question: what, if anything, is the 5th channel currently used for? >
Bump maps in baked textures. IIRC, only the avatar pipeline produces/consumes that channel. Also, IIRC, the logic is entirely client-side at the moment. > Could it be used for normal maps if it is currently unused? > If so, then we could do this entirely clientside, assuming 5 channel > textures can be uploaded. Of course there would still need to be a > way to disable the alpha channel during upload while preserving the > normal map channel. > That would technically be possible. The asset system does do verification and modification of various asset types on upload (including textures), but - again, technically - this would probably work, possibly requiring some minor changes to the asset verifier. However... The biggest challenge is the lack of support for multiple channels in JPEG2000-producing/consuming tools. Many tools only work with 3-channel images, and complain about 4. Combined with the lack of tools for authoring JPEG2000 images in the first place, I'm not sure you'd want add another 3 channels to the image for the normal map. It would also mean you couldn't re-use a normal map with two textures, e.g. to allow color variants on a base mesh. Avoiding two separate texture asset fetches (colors and normals) per face might be a significant win, but I'd want to see the numbers to prove it first. (For comparison, the 13-channel RAW data used for uploading/downloading region terrain and parcel data is pretty pesky to work with. Sure, it works with PhotoShop, and is a technically simple single file backup format, but putting all of that data into a single image is fragile that you expect users to edit is not particularly user-friendly.) > Ricky > Cron Stardust > > On Monday, January 10, 2011, Joshua Bell <j...@lindenlab.com> wrote: > > On Mon, Jan 10, 2011 at 9:28 AM, Dave Booth <d...@meadowlakearts.com> > wrote: > > > > Thats a pretty good bit of thinking out loud there, Ponzu.... > > > > Personally I'd say thats a "clean" fix for this. However it all depends > > on how things are stored server-side - if the asset server code > > automatically assumes that every texture has an alpha channel and > > supplies a "solid" one for those where the upload doesnt provide one, > > any benefit of specifying at upload time is moot. > > The asset upload/storage system handles 3, 4 or 5 channel JPEG2000 > textures and doesn't tinker with the channel data. The bulk of the textures > in the asset system are 3-channel (RGB). > > > > (Excellent question, BTW.) > > > > > _______________________________________________ > Policies and (un)subscribe information available here: > http://wiki.secondlife.com/wiki/OpenSource-Dev > Please read the policies before posting to keep unmoderated posting > privileges >
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