Alpha draw order bug without the alpha?
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Sindy Tsure
Will script for shoes
Join date: 18 Sep 2006
Posts: 4,103
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10-04-2007 17:23
XP, 7800GT, RC viewer 1.18.3. Dunno if this is a well-known problem or not..
Been goofing with making a prim cloud. Made a simple gray gradient on a white background - no alpha stuff - and slapped it on a bunch of differently sized spheres. When I move the camera, the prim positions seem to change!
Is this a known issue? Attached is the texture and two screenshots of some torus/sphere/ring spheres taken from slightly different angles. The prims are all the same size, at the same height and weren't changed between shots..
Any idea?
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Chosen Few
Alpha Channel Slave
Join date: 16 Jan 2004
Posts: 7,496
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10-04-2007 17:45
For that to be happening, you must have some degree of transparency in the image somewhere. If your source image was PNG, perhaps you assigned one of the colors to be transparent without realizing it. If it was TGA, then you probably saved as 32-bit instead of 24-bit.
It's also possible that you've got a script in the objects, assigning an alpha value, but since they don't appear to be at all see-through, that's probably not likely.
What happens if you turn on Highlight Transparent? Do the objects turn red? If so, then you know for sure that there's transparency in the texture.
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DanielFox Abernathy
Registered User
Join date: 20 Oct 2006
Posts: 212
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10-04-2007 17:46
I've noticed this can happen when uploading PNG's ... try saving as TGA instead
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Sindy Tsure
Will script for shoes
Join date: 18 Sep 2006
Posts: 4,103
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10-04-2007 17:47
Oh! It does go red with highlight transparent!!
/me, apparently, is an idiot.. Good tip - ty!!
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Sindy Tsure
Will script for shoes
Join date: 18 Sep 2006
Posts: 4,103
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10-04-2007 18:07
From: DanielFox Abernathy I've noticed this can happen when uploading PNG's ... try saving as TGA instead I started over, using Paint.NET here, being careful not to do any transparancy and got the same thing.. Maybe it is a upload bug. Using jpg caused it to act the way I expected it to.. |
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Day Oh
Registered User
Join date: 3 Feb 2007
Posts: 1,257
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10-04-2007 19:11
Be sure the color depth is 24-bit as opposed to 32-bit
Edit: Just noticed someone already said that... but hay, I don't see how you can go wrong with 24 bits
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Sindy Tsure
Will script for shoes
Join date: 18 Sep 2006
Posts: 4,103
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10-04-2007 19:26
Just being 32-bit gives it an alpha chanel, even if there's nothing transparent about it?
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Day Oh
Registered User
Join date: 3 Feb 2007
Posts: 1,257
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10-04-2007 19:59
I do think so. You may already know the extra 8 bits are the alpha channel. It's enough to keep the image from being useable as a ground texture, for example.
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Johan Durant
Registered User
Join date: 7 Aug 2006
Posts: 1,657
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10-04-2007 21:05
Are you sure you haven't just touched the arrows for the transparency attribute in the object?
EDIT: Just saw the bit about jpegs working fine, so this wouldn't be it.
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Void Singer
Int vSelf = Sing(void);
Join date: 24 Sep 2005
Posts: 6,973
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10-05-2007 04:04
note about .TGA and some apps
some apps have an "intelligent" save as for tga....
instance one (PSP had this as of v7, dunno if it still does)
it only options you to save up to 24bit, but if it contains an alpha channel it bumps it up to 32bit w/o telling you
instance two (dunno who if any do this)
all tga save with a default 24bit+8bit alpha, regardless of if you wanted an alpha or not... blank alpha layers can cause sorting issues
instance three (I belive many do this)
tga is saved with the options last used, if you added an alpha layer last time, you get one next time, as a default, unless you change it
again, blank alpha layer causes sorting issues
weird of chance...
you said you were using a gradient? I know sometimes apps think that if you have transparency in you base image they should automatically add an alpha layer for formats that use it, to simulate the transparency in the image... if the gradient has transparency, it's possible
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Ceera Murakami
Texture Artist / Builder
Join date: 9 Sep 2005
Posts: 7,750
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10-05-2007 07:04
From: Sindy Tsure Just being 32-bit gives it an alpha chanel, even if there's nothing transparent about it? Yes. You can make a solid blue square, save it as 32-bit TGA, and Sl will treat it with the same alpha sorting issues as any texture that has an ambedded window or other visible transparency. The sorting glitch is dependant on it being a 32-bit texture, not on it being made with visibly transparent areas. For that reason, a few of the stone textures in the Library show the sorting glitch, because they were incorrectly saved by the Lindens as 32-bit textures! At TRU just this week, we just had to issue an advisory notice to our artists, because a few of the newer ones had accidentally saved some floor textures as 32-bit, and a customer who bought them saw they had the sorting glitch problem. (I believe they have fixed those textures now, and that they got replacement textures sent to the clients, free of charge.)
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Chosen Few
Alpha Channel Slave
Join date: 16 Jan 2004
Posts: 7,496
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10-05-2007 08:07
From: Void Singer ...blank alpha layers...
... blank alpha layer...
...add an alpha layer... AAARRRGGGGHHHH! Alpha channel, alpha channel, alpha CHANNEL. There's no such thing as an alpha layer.
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Void Singer
Int vSelf = Sing(void);
Join date: 24 Sep 2005
Posts: 6,973
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10-05-2007 09:49
From: Chosen Few AAARRRGGGGHHHH!
Alpha channel, alpha channel, alpha CHANNEL. There's no such thing as an alpha layer. lol you win!!! it's a (bad?) habit I've picked up from a few programs that treat the alpha CHANNEL as a layer =) (which if you think about it, it really is =X) ::runs away:: |
