Mesh (Content Creation)
Opensimulator: Content Creators: Models: Mesh
A polylist mesh, usually simply called a "mesh", is a 3D model generated from a complete list of data downloaded from the server. A mesh has amuch higher streaming cost than a prim or a sculpt but offers far more flexibility for the content creator.
Faces
A mesh in Opensim can have up to eight faces.
A mesh with more than eight faces can be uploaded but the uploader will split it into two or more objects and it's not very good at it so it's better to split manually before uploading.
Level of Detail
Each LOD model has to be created before or during upload.
Knowing how to make good LOD models is one of the most important, perhaps even the most important, skill a mesh maker for Opensim needs. The uploader can generate them automatically but the result is hardly ever satisfactory It's a balance: simplify the LOD models too much and you get the typical Second Life mesh that turns into a mess when viewed at a little bit of distance, don't simplify enough and you add a considerable extra load to the render engine. Do it wrong (or use the uploader's auto-generated models) and you get a mesh that both collapses at a distance and adds unnecessary render lag. Mesh geometry is by no means the biggest cause of render lag but it is still a significant factor and should not be ignored.
LOD model creation is a typical "minute to learn, lifetime to master" skill. Very few 3D artist know how to make great LOD models for Opensim but making perfectly acceptable ones isn't that difficult and making something slightly better than what the uploader usually produces is something most people with a little bit of 3D modelling experience can easily learn.
It's hard to find good information on the topic though, especially since the way Opensim (and Second Life) handle LOD is so different from how other game and virtual world engine do it. This is probably why even most seasoned professionals seem to struggle with getting it right.
Physics
The physics model is separate from the main visual models and the LOD models. See the links below for some guides how to make good mesh physics for Opensim.
Links
Documentation
Articles on this wiki:
- Mesh (At the moment (May 2023) this page is seriously outdated and incomplete but it still has some useful information)
Guides
Lag: Geometry (prims, meshes and sculpts)
- Link: https://chinrey.blogspot.com/2019/03/lag-geometry-prims-meshes-and-sculpts.html (confirmed 2023-05-27)
- Author: Tess Juel
A short article on the differences in lag caused by prims, meshes and sculpts.
Second Life Mesh Physics 101
- Link: https://chinrey.blogspot.com/2020/09/second-life-mesh-physics-101.html (confirmed 2023-05-27)
- Author: Tess Juel
Not all of the info here applies to opensim since it uses a different physics engine than SL.
How to make good mesh physics
- Link: https://www.kitely.com/forums/viewtopic.php?f=25&t=5691 (confirmed 2023-05-27
A similar article to the one above but more geared towards opensim.
