Hey, so we have been trying some things when asking ourselves which would be the best way to unwrap simple shapes.
I had stretching issues when making large islands and the criteria are those:
(Yes this is going to be very basic, so basic in fact that I never really thought about that stuff too hard)
Minimize small islands that waste tons of UV space and are just a mess if you ever want to texture anything manually, especially as many packing algorithms do not pack small islands well, so have as much of the islands in one piece to have the UVs organized, clean and maximize space2.
Optimize Vertice count and minimize edge cuts3.
Minimize skewing / stretching4.
Ease of Unwrap
Here are the candidates:
And here is the bake:Edit2: After some troubleshooting: If you have matching tangent spaces these can all be baked without stretching.
The below result holds true in non optimal environments, (if you want to bake normals that work in any environment, like selling assets on the asset store / 3D Marketplaces or for clients you dont know about)
The full island has heavy skewing and the "T" shape does not work as well as I thought
Now onto the real meat: Vertices
Here it becomes very clear why cubic auto unwraps are really bad. They waste a lot of space, are hard to find and a shitton of vertices.
Remember real in-engine vertice count matters over triangle count. These all have the same amount of triangles, but performance is far from the same.Edit:
My test seems to use the worst case, not ideal matching tangent spaces.If you have ideal tangent space matches, number 2 and number 4 would be the most optimized if you put in the extra effort over number 1,
in non matching tangent spaces (or you make assets for 3D Marketplaces with all kinds of end user spaces), this here is my conclusion:
So we have 2 candidates:Nr1 - Baking Roller unwrap
+ Very Simple to unwrap
+ Saves a little bit of UV space due to less border surface area (vs Nr6)
+ Majority of the UV space is at one place
- Makes the UV messy again with tons of small solo pieces, hard to work with when doing manual edits, bad oversight, ugly uvs
- 18 Vertices, worse on performance but acceptable
- Has seams on a lot of the edgesNr6 - [ ] Hugging unwrap
+ Great performance with 16 out of a potential minimum 14 vertices
+ Nice clean and easy to work with UVs with splits in 2 larger pieces
+ Has long Pieces which are easy to paint on and have a little less seams
- Harder to unwrap
- More surface area = potentially more spacing area if the packer is unusually good with tiny single pieces like Rizom UV
So in this simple shapes example I think the U+U unwrap is the best choice despite being a little harder to pull off,
Let me know what you think or if I am missing something. I have not tried a world space normal to tangent space conversion or anything the sorts, and no support loops have been used on the lowpoly. Id like to hear some tricks and tips if there are some.