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arno

Whats the difference between these types

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Hi Guy'sCan someone please give me a rough difference between these file types pleaseDXT1 and DXT3also, what would happen if someone created a scenery item in 16 bit, and I changed it to DXT3Thanks.

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Hello Steve, - DXT1 -- for scenery or aircraft, 1 bit reserved for alpha channel so in scenery is used to make parts of the texture transparent - DXT3 -- for aircraft only, 256 shades of gray for alpha channel so is used in aircraft for different levels on shininessIf an aircraft texture has no alpha channel, then there is no point in using DXT3 and DXT1 should be used. Why? Because DXT3 is twice the size of DXT1.If you convert all large textures in scenery to DXT1, you will immediately see an improvement in performance.Best regards.Luis

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Well, that's not completely true. You can use DXT3 for scenery textures, if you need multiple levels of transparency.

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Thank you for the correction, Andy. You are absolutely right. One can also use 32-bit images if one is so inclined.Best regards.Luis

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Another minor note is that the DXT3 format has a 4 bit alpha channel, so that means you have 16 gray colors to use and not 256. But that still means you only need the DXT3 format if you want different levels of transparancy, DXT1 is fine in all other cases (and saves half the diskspace).

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Hi Gang.Thank you all for the replies, and for explaining this to me.I do think I have understood your explanations, and I do appreciate them.if I can, can I please also ask something else, I have noticed a lot of the newer scenery's are now coming out in DXT3 format, and are mipped, and yet a long time ago I mentioned this to other people and got some very damning replies, literally telling me it was rubbish, and that I don't know what I am talking about, and yet, ALL of the textures by default in FS9 were DXT3, AND mipped, so I think it was they who were wrong.the other thing is, I have noticed some significant differences in some of the add-on aircraft makers techniques as well, for example captain sim's C130 uses a panel of 16 bit, and some others use 32 bit, not miped mapped of course, but then again some use 8 bit.This is very confusing to me, and I am just trying to get an understanding of why they use so many different settings or types.I know that you guy's have probably been doing this sort of thing for a long time, and that to have someone like me come along and start asking basic questions is a pain, but I do appreciate you're answers and time, I have read up on some of these things, but, to be honest, they are so confusing they might as well be in hieroglyph.Thank you all once again.

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I think if you d/l the DXTBmp program, there is a help file with a lot of good info on the history of different file formats used by FS in the past and currently.scott s..

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Scott,Thanks for reminding about the Help File. Lots of very good basic info. Is it safe to assume that the supported file types mentioned for FS2000 carry over entact to FS2004?Thanks,Dick near 5G8

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I'm pretty sure that is the case. All the old formats, back to raw 8 bit still work.scott s..

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Yes, all old format still seem to work fine. But it is adviced to use DXT textures (with mipmaps) nowadays. So for new creations I would not use the other formats anymore.Using DXT3 only makes sense if you require an alpha channel with more than 1 bit, for all other textures DXT1 is fine. So in general that should be the default format.

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