Kyrah Abattoir

Yup you got it, and you can draw masks by hand, or generate them on the fly (various noises, pointiness, cavities, etc etc...) For all intents and purposes, node graphs are essentially visual shaders, you are building a mathematic equation to drive the properties of each rendered pixel.

A mask is typically a black & white texture (but not necessarily) that you feed into your node graph to combine multiple paths into one on a per UVpixel basis, you obviously need to give "some kind" of unwrap to your high polygon mesh if you plan to do that on it. Example below

For smaller details like stitches I usually draw a mask & a bump map in Krita and integrate them into my blender material. And yes, if you use normal/specular maps only people with ALM enabled will get the full effect. But unless policies have changed at Linden Lab the non-alm renderer is on its way out. You can still bake "some" (not all or you will fight against the normal map) details into your diffuse map for those users. My position, realistically, is that, if you can't run ALM, you are very unlikely to have the ram/vram required to support larger textures anyway.

Make a checker material for your object where the check count is equal to your texture resolution if you want to get a feel on the distorsion. Do keep in mind that transitions between pixels are filtered, unlike what photoshop/gimp shows us. so a stretchy pixel might not necessarily be that visible.

Pretty much, the extra data of your normal map makes up for the difference, and the high poly subdivided model essentially never touches SL.

Yup, you use the full memory that your texture occupies regardless of whether you are using that piece of texture for something or not. It's not always possible but try to aim for 90% coverage, unless you are using a tiling texture in which case, obviously you want your UV to conform to the tiling instead. This is one of my most recent uvmap:

@Butler OffcourseSince you are going to bake anyway i'd recommend to create a separate low-polygon model of your shoe, using surface snapping with your highpoly as a reference so you don't have to guess smoothness too much, and try to reconstruct a "close approximation" without using subdivision, only adding what is strictly necessary and not going to be highlighted enough by the normal map.

@Butler OffcoursePassing comment on your UV, you are wasting a massive amount of texture space having your object unfolded like this. You should consider introducing seams to break it up further and make better use of that space.

It is a problem that exist in pretty much every game under the sun, some are better at mitigating it, but alpha blended surfaces are rendered in reverse order to account for multi-layered surfaces.

The audacity of those mute/deaf people using SecondLife, right?

Yeah it is called "edge splitting" Edges get split for various reasons: Material change. UV seam. Hard edge normals

A word on strided lists, I'm not sure they are beneficial in any way compared to just using two lists. since lists used as arguments are copied around, it seem that two lists would move around less memory than a strided list?

Pro tip, there is an interesting little pattern you can use for flip flop systems: on = !on;

Yeah i think that normal map is already here but there is something wrong with your model's shading. or something wrong with now you baked those normals because all that flat blue indicate "no normal differences" which is simply not possible given that your upload is smooth shaded. Speaking of, why is it if the normal target was flat shaded?

https://jira.secondlife.com/browse/BUG-227448 It is definitely something wrong with how meshs are either stored, or rendered.