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[Article] DDS Converter

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Re: [Article] Image Engine

Postby giftfish » 28 Feb 2016, 16:26

Creeper, please stop editing the page. Your making it difficult for me to roll back the changes.

Also, please stop changing the wording for the credit box at the top of the page. I get you prefer your wording, but what I've changed it to is more succinct and uses less words. Considering I'm basically responsible for editing the entire wiki, fewer words are always better.

EDIT: And, I see you rolled it back, lol. Thanks. On to TPF Tools!
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Re: [Article] Image Engine

Postby KFreon » 29 Feb 2016, 06:57

@gift: 100% alpha is no alpha. The default alpha is 100%, because if a pixel has an alpha value less than 100%, it starts becoming transparent.
So if the "Show Alpha" checkbox doesn't do anything, it means there isn't any alpha.
BUT it's worth noting that sometimes the alpha can be hard to spot (tiny little area that's supposed to be transparent).
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Re: [Article] Image Engine

Postby giftfish » 29 Feb 2016, 16:24

KFreon wrote:@gift: 100% alpha is no alpha. The default alpha is 100%, because if a pixel has an alpha value less than 100%, it starts becoming transparent.
So if the "Show Alpha" checkbox doesn't do anything, it means there isn't any alpha.
BUT it's worth noting that sometimes the alpha can be hard to spot (tiny little area that's supposed to be transparent).

Hm.

What you say makes complete sense, and is what I was thinking. BUT, why then are all these programs telling me that an alpha layer is present? That's the part that is confusing me. They aren't just RGB images, they are RGBA/ARGB. They have an alpha layer. I can open other textures that are specifically RGB, but these are ARGB.

Any ideas why?
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Re: [Article] Image Engine

Postby KFreon » 01 Mar 2016, 07:35

I can only assume one of two things.
1) The programs see that the format can contain alpha and thus checks for it, doesn't see any so just creates a blank channel so the programmer had less work to do.
2) The header of the DDS might have some obscure flag that indicates the presence of alpha. I don't know of it, but who knows.

Is it that big of a deal though?
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Re: [Article] Image Engine

Postby giftfish » 01 Mar 2016, 15:15

KFreon wrote:I can only assume one of two things.
1) The programs see that the format can contain alpha and thus checks for it, doesn't see any so just creates a blank channel so the programmer had less work to do.
2) The header of the DDS might have some obscure flag that indicates the presence of alpha. I don't know of it, but who knows.

Is it that big of a deal though?

Well, not sure if it's a big deal. I've really never messed with the alpha channel in all the image editing I've done. I mess with layer transparency, but not the alpha of the entire image.

My personal concern is two things:

1. I know what to explain in the wiki.
2. Users know whether or not a vanilla game texture has an alpha, and thus how to format their texture properly. RGB is a different format from RGBA, one has alpha, the other does not (theoretically).

I guess the best course of action is going to be to advise the user/modder to ensure the alpha channel -- if present -- stays identical to the game's vanilla texture. That's the only way to prevent problems with 100% accuracy.

What I'm wondering, though, is if this somehow ties into the bug I get when using GIMP, where some DXT5's are totally uneditable as their alpha is so transparent. Other users have reported this, as well. I can open two DXT5s and one will be fine and the other won't. And, the bad one when opened in PS will look fine. Like you're saying, I wonder if there's some missing data, somewhere.

At any rate, I know what to say for the wiki, and that was my primary concern. Thanks :)
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Re: [Article] Image Engine

Postby CreeperLava » 01 Mar 2016, 16:37

I think you can change the opacity of the alpha layer in gimp. It allows to actually see the texture when efiting it.
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Re: [Article] Image Engine

Postby giftfish » 01 Mar 2016, 16:45

CreeperLava wrote:I think you can change the opacity of the alpha layer in gimp. It allows to actually see the texture when efiting it.

Yes, I've tried that; it doesn't work. The texture still doesn't look as it should -- as it does in PS.
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Re: [Article] Image Engine

Postby giftfish » 01 Mar 2016, 18:34

@Kfreon -- Hm, still thinking about this weird alpha thing.

With the DXT1s, doesn't it indeed matter, though? B/c the structure is different, depending on whether alpha data is present or not:

No alpha -- compressed, 24-bit RGB (3 channel; 5 bits/channel for Red/Blue, 6 bits for Green)
Alpha -- compressed, 16-bit RGB w/1-bit alpha (4 channels; 5 bits/channel for colors, 1 bit for alpha)

So, isn't the game going to read that differently, and isn't the toolset going to care? Or, since they both use DXT1 compression, is it irrelevant?
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Re: [Article] DDS Converter

Postby KFreon » 02 Mar 2016, 07:19

You should be able to disable the alpha layer in GIMP right? For everyone's sake, I hope it's possible...

It's all handled rather cleverly, but basically the logic behind which type of DXT1 an image is is part of the DDS spec, and every image/engine tool will respect it.
This includes the game and the image engine.

CAVEAT
If you put an alpha DXT1 in the game where there wasn't one before, odd things could happen. I dunno what it'll do.


Just so it's clear, this problem is only applicable to DXT1 since the others all have explicit alpha channels.
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Re: [Article] DDS Converter

Postby giftfish » 02 Mar 2016, 15:02

@Kfreon -- Hm. This is interesting. GIMP's alpha channel is harder to play with than PS's, but let me do some testing today.
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