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How does BoM (and Omega) handle UV mapping?


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It's probably how my usual mesh avatar body, looks good with low complexity, uses a different UV map, but how much does it matter?

My first guess is that the BoM system doesn't give a monkey's about the UV mapping. It's never mentioned, but why should it matter? The samples pictured use a default texture, there's signs of shape-related distortion, but it looks like what you would expect. The demo is a universal wearable that uses classic avatar UV mapping

So why does nobody mention this? These universal wearables have to be made with a shape that matches the mesh body, and they don't have to have the same UV map, but the alpha mapping effect is going to be messy if they don't.

It's as if the Lindens writing the documentation have never made a rigged mesh, and never had to work with UV maps.

I have used tools, made for the Poser program, which will translate textures from one UV map to another, so it can be done, but what does the Omega Applier system do? Again, nobody says, but it's simplest if the target meshes all use the standard classic avatar UV mapping.

I have fitted mesh cloths on the Marketplace, but I don't use this classic UV map. I have some sweaters, and they're set up to reflect the parts of an RL sweater, with the direction of the knitting constant, so I can used a tiled normal map, easy to download and using RAM efficiently. It looks pretty good. If BoM is UV neutral, it's not going to be a problem. Yes, I know, you can't use BoM for anything but diffuse channel textures, but you have to use the same UV mapping.

 

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26 minutes ago, arabellajones said:

It's probably how my usual mesh avatar body, looks good with low complexity, uses a different UV map, but how much does it matter?

My first guess is that the BoM system doesn't give a monkey's about the UV mapping. It's never mentioned, but why should it matter? The samples pictured use a default texture, there's signs of shape-related distortion, but it looks like what you would expect. The demo is a universal wearable that uses classic avatar UV mapping

So why does nobody mention this? These universal wearables have to be made with a shape that matches the mesh body, and they don't have to have the same UV map, but the alpha mapping effect is going to be messy if they don't.

It's as if the Lindens writing the documentation have never made a rigged mesh, and never had to work with UV maps.

I have used tools, made for the Poser program, which will translate textures from one UV map to another, so it can be done, but what does the Omega Applier system do? Again, nobody says, but it's simplest if the target meshes all use the standard classic avatar UV mapping.

I have fitted mesh cloths on the Marketplace, but I don't use this classic UV map. I have some sweaters, and they're set up to reflect the parts of an RL sweater, with the direction of the knitting constant, so I can used a tiled normal map, easy to download and using RAM efficiently. It looks pretty good. If BoM is UV neutral, it's not going to be a problem. Yes, I know, you can't use BoM for anything but diffuse channel textures, but you have to use the same UV mapping.

 

As long as the layers being baked together are graphically appropriate for the UV map of what they're being baked onto there's no problem. I've literally used BOM to texture a helicopter I was wearing as a test. Tattoos, alphas and universals are completely layout-agnostic; skins have a small area in the corner of the head that can't be used for a different layout. The old "clothing" wearables are a different case because of the old "resizing" thing that could be done with sliders.

All the Omega system does is say, "Texture that thing with the texture with this UUID" - it's also layout-agnostic.

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As Theresa says, baking doesn't really know anything about UV maps. You could think of it as just sticking images one on top of another like a stack of  pancakes. As long as all the images have the *same* UV map, things will work fine. If the images are intended to fit different UV maps, you could wind up with graphical inconsistencies. So in the most common case, all the textures in your various wearables will be using the standard avatar UV map, or something close to it, and that will work fine. But if you had an avatar for a snake that used a completely different UV map, you could make compatible tattoos or clothing for the snake as long as they all used the same UV map as the model was designed for. Whether snakes should have tattoos or clothing is a separate question...

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OK, thanks, that makes sense, but why the hell couldn't you just say so?

The sticking point is going to be the interaction between the basic avatar and the mesh body. If you can't maintain the current invisibility  and also use BoM, it looks as though I'll be using a horribly more complicated mesh avatar if I want to use BoM. And forcing Alpha Blending worries me.

Right now, I'm thinking BoM is going to be useless for me

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2 hours ago, arabellajones said:

OK, thanks, that makes sense, but why the hell couldn't you just say so?

The sticking point is going to be the interaction between the basic avatar and the mesh body. If you can't maintain the current invisibility  and also use BoM, it looks as though I'll be using a horribly more complicated mesh avatar if I want to use BoM. And forcing Alpha Blending worries me.

Right now, I'm thinking BoM is going to be useless for me

When one of the bake channels (i.e. the head) is being used on an attachment, the corresponding part of the default avatar is automatically kept from displaying without needing an alpha to do that. For instance, if you wear a head that is using the avatar head bake, the head of the default avatar is automatically erased and the texture that would have been on the avatar head is instead sent to the attached head.. This means that the head you wear can use any UV map and you don't have to worry about the default avatar at all.

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53 minutes ago, Theresa Tennyson said:

When one of the bake channels (i.e. the head) is being used on an attachment, the corresponding part of the default avatar is automatically kept from displaying without needing an alpha to do that. For instance, if you wear a head that is using the avatar head bake, the head of the default avatar is automatically erased and the texture that would have been on the avatar head is instead sent to the attached head.. This means that the head you wear can use any UV map and you don't have to worry about the default avatar at all.

And for any left over parts of the base skin not in use, you can just wear a alpha set to hide the specific chunk

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2 hours ago, Vivienne Daguerre said:

I just want to clarify to make sure I understand this correctly. Please correct me if I am wrong.

As I understand it, a mesh body maker must squeeze his mesh UVs to fit the layout of the classic system avatar if you want that mesh body to be able to wear old system clothing. Am I right or wrong?

If you want to wear system clothing that was originally made for the system avatar (or mesh bodies based on the same basic UV map) then the avatar they're worn on will need to be compatible with that UV map. However, there's nothing preventing new system wearables being made for an avatar with a completely different UV map. Note that there are weird conditions in the layout for the old "clothing" wearables (i.e. non-tattoo items that could be adjusted for fit in the appearance editor) that would make it tricky to use those for a different layout.

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