#SL Content-Mesh Meeting Week 11

There is lots of confusion about what will happen to the Mesh User Group (UG). We do know it met today and Nyx, Vir, and Runitia were there. Because the User Groups’ page was edited to remove links to the group’s home page, we didn’t have much of an agenda. You can reach the page here: Content Creation/Mesh Import User Group. Watch that page for more information on the group.

Unofficial Mesh UG Meeting

The Future

It’s unknown. Last week Nyx said he would find out what he could. When I asked about it this week, he said, “We’re not quite ready to make an announcement as to how we will be handling these meetings in the future. Stay tuned!” So, the group’s future is still unknown.

Too Many Vertices

There is a strange thing happening with mesh import. In certain cases the vertex count goes way up. For a discussion of the problem see warehousefifteendesigns’ post: Two different vertices count.

Gaia Clary describes some of what is happening:

The vertex count as calculated by the mesh importer is more complex than it may look in first place.

  • It first counts all vertices just like you expect (and like your 3D modeling software shows you),
  • If you have used seams (and you most probably HAVE used seams), then you get additional UV vertices, because at the seams the UV-vertices are doubled and such need extra space.
  • If you use flat shading instead of smooth shading, i believe that each vertex which belongs to a flat shaded face gets counted as many times as it is shared by other flat shaded faces. this is because with flat shading the importer needs to store the vertex normals according to each adjacent face. (I must admit that this explanation is a guess and if it’s wrong, please can anyone correct me ?)

 Hence the displayed number of vertices in the mesh importer can be significantly higher than the number of vertices shown in your modeling software (which only counts the actual number of vertices)

Mesh Format

Mesh Data Format Diagram by Drongle McMahon

Drongle McHahon explains more about mesh in this thread: Mesh asset format picture. He provided this image to help understand. The format is described in the wiki here: Second Life Mesh Format.

Runitai sums it up saying, “Basically — if one “vertex” has multiple normals or texture coordinates, it’s more than one vertex.”

All this is well and good, but Jr4201 Kruyschek points out a problem: Here is how I first found it: I uploaded a car door without a problem, then I uploaded the same car door mirrored. It’s prim count was 8 times higher. (Edited for clarity)

Matching Sculpty LoD

Davido Chrome asked how much a mesh object needs to simplify per step to match what sculpties do? I suppose that is useful to know for those converting sculpties to mesh.

Drongle McMahon answered:  Sculpties go down 4x per step until they are 4×4 vertices.

Runitai Linden says, apparently it’s more complicated than that now. The actual code was brought up to see. You can find it in the repository. Apparently it gets complex because sculpties are no long square.

Rinitai suggests that probably the easiest thing one can to do is use the render info display to get a triangle count of your selection then zoom out to see how it changes. I didn’t know how to do that for a ‘selected item.’ Develop->Show Info->Show Render Info. One of the lines near the bottom of the display shows the triangle count of your selection or the region if nothing else is selected.

Broken Shiny On Invisiprims

Invisiprims are kind of out of style now. In general they were used to hide parts of avatars. It was very common for shoes that needed to hide feet. Now Alpha Layers take over that job.

However, it is possible to use invisiprims for building special effects in buildings and avatar clothes. When Deferred Rendering was added shiny on invisiprims broke, changed how it behaved. Simulated windows and ghostly avatars stopped working and look goofy.

Avatars at the Meeting

Also, people that make things for one arm avatars need invisiprims. Alpha Layers cannot hide just one arm. Invisiprims are needed for that task.

It looks for the foreseeable future invisiprims will remain broken. Runitai said, “While shiny transparencies are technically possible, there are no plans to work on that at this time.”

Cloudy, Grey, Blurry

Nyx still needs more test results from the Runway Project viewer. Nyx is working on figuring out why avatars are failing to rez, stay grey, or blurry. You can get a copy of the viewer: Runway Project Viewer Latest.

I wrote about the problem and the effort to help the Lindens find the problem cause in: #SL Clouds, Grey, and Blurry Avatars. More viewer logs are needed, but they have to come from the Runway Project Viewer.

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