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• Mesh (At the moment (May 2023) this page is seriously outdated and incomplete but it still has some useful information)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.

Tutorials

Internal links

• How To Upload Mesh

Tools

Blender

• Link: http://www.blender.org/ (confirmed 2023-05-25)
• Type: Program
• Use: Mesh models, Materials, Terrain, Animations
• OS: Windows, Mac, Linux
• License: Open source (GNU GPL)
• Price: Free

Blender is the free open source 3D content creation suite, available for all major operating systems under the GNU General Public License. It is mainly known as a mesh editing/creation program but is also a powerful tool for creating animations, materials and terrains.

Blender add-ons

• Auto-Building for Blender
  • Link: https://juliengauthier.gumroad.com/l/nzifx (confirmed 2023-09-07)
  • Type: Program add-on
  • Use: Building model generator
  • OS: Windows, Mac, Linux
  • License: Commercial
  • Price: CAD 20-60

Monster Mash

• Link: https://monstermash.zone/
• Type: Online tool
• Use: Generate shapes
• OS: Any
• License: ?
• Price: Free

This may be more of a fun gadget than a useful tool but it is really fun and may have some practical uses too. You draw a shape on the screen and then Monster Mash inflates it into a 3D shape. The shape can be animated and distorted and exported as a mesh in obj format. The mesh you get is very high poly so it shouldn't be used in OpenSim as it is, it needs to be cleaned up in BLender or another modelling program first.

SketchUp

• Link: (missing)
• Type: Program
• Use: Mesh models
• OS: Windows, MacOS
• License: Propietary?
• Price: Free?

Entry level mesh model editor/creator software. SketchUp is CSG based which means it tends to generate rather "dirty" and render heavy meshes. As the name indicates, it was made as a 3D sketching tool and never intended for making models for real time rendering. Use it carefully!

Wings 3d

• Link: http://www.wings3d.com/ (confirmed 2023-05-28)
• Type: Program
• Use: Mesh models (and to some degree sculpts)
• OS: Windows, MacOS, Linux
• License: Open source
• Price: Free

A simpler and less developed free 3D modelling program. This is a good alternative for many since, unlike SketchUp, it offers all the functions you really need to create mesh for opensim and much fewer of the often confusing mass of functions not relevant for our purpose than Blender and the big commercial programs.

Unlike the other 3D modelling programs Wings 3d also has some limited support for sculpts, limited since it only supports 32x32 format sculpt map. This function is a bit compromised though since it requires special templates that can be hard to find.

Other tools

• makehuman - Realistic 3d humans, open source for Windows, OSX, Linux.
• 3DS Max
• Maya
• Zbrush