Hello community,
I have to deal with performance issues, because my model has too much vertices. In other threads I have read, that Unity creates five times more vertices then the 3D app (for position, normal, tangent, uv coordinate, material) right? In the import settings I set the tangent option to “none”, because I can’t see any differences, if I import or calculate the tangents.
Obviously I need the position, normal and material information, but what about the uv coordinate, if I’m not using any textures? For example the Mobile/Vertex Lit shader or the Legacy Vertex Lit without any texture set. Do I need the UV coordinates otherwise? And if not, how is it possible to get rid of them and reduce my vertex count to 80%. Or is my understanding not correct?
Thank you for any answer!
All objects contain at least 1 UV set and you can not disable it. It’s still in the mesh data.
Even you choose not to export the UV set from 3D software. It will automatically make a default one.
If you are developing mobile games. Take care of real-time lighting. Use texture atlas.
Material as opaque as possible. Less using fancy shader. Should enough for optimization.
@AkiraWong89 that is not correct.
You do not need UV data on your mesh if you’re not going to use it. In 3dsMax use the Channel Info tool to clear the UV channel data then export normally. On import in Unity you can click on the mesh object inside your fbx and it will list the vert data that is present.
UV data is also imported or created for lightmapping.
You need UVs for lighting to work (when using baked or realtime GI).
If you don’t import UVs, they will be required to be generated for you, otherwise, you will not have a very fun time with GI.
You need to reduce the vertices in the model, so you don’t have to be concerned about this issue.
Importing UVs for textures is done 99.99% of the time. What is your 3d model?
I don’t know much about the normals/tangets, but I’m pretty sure they are required for lighting/shadows.
Lets talk about the specific question of vertex count reduction. The addition of UVs, normals, tangents, etc do not in themselves increase the vertex count, so simply removing the UVs isn’t likely to reduce your vertex count by a significant amount.
A mesh is made of many triangles, with three vertices each. Each vertex is at its most basic a point in space, but it can also store extra information like texture UVs, normals, etc. If two triangles have a corner in the same position they can share a vertex, but only if both triangles have the same information for that point. For example if you have two triangles sharing an edge and one is entirely green and the other is entirely red they can’t share vertices and both triangles will require 3 unique vertices each, 6 total for the two triangles. If they’re both the same color, or that entire edge is the same color, then they can share the vertices and then there’s only 4 vertices total for those two triangles.
The vertices can have as little or as much data as needed, but if any single bit is different between faces that use it it’ll split and become two or more depending on how many triangles are using that position.
So, worse case would be something like a faceted diamond model or something with every face a different color like PolyWorld. In that case it doesn’t matter what else you do with UVs, every single triangle has 3 unique vertices.