Linking prims to mesh? No Problem! - A Guide to mixed Linksets

One of the most notorious myths in Second Life is that you can't link prims and sculpties to mesh objects. It will shoot your Land Impact through the roof and might even crash the sim you're on. 

Well, I do this all the time. 

 

Um, NO, I'm NOT crashing any sims (or at least not so far...)! But I do mixed linksets a lot. In fact, there is hardly any build I make that doesn't contain mesh parts and I still love sculpties, they simply do have their purpose, even in times of mesh.  And I tend to always link as much as I can - it's so much nicer if you have only 1 object to handle instead of several. Even if you put them in a rezzer, the less elements you have in there, the more likely it is to rezz properly. 

 

Of course, like in every myth, there is some truth in it: 

When you link prims and sculpts to mesh objects, there is always the chance to have one or another prim or sculpty that doesn't behave well in the linkset and makes the LI go up higher than expected. But in most cases, this can be avoided by following a few simple rules when linking your mixed build.

 

Example:

This beautiful antique bookstand that we make in the Spell Book Class consists of  5 single elements: the table, the bookstand, the book, the candle and the wick. 

 

So in this build, we have 2 sculpted prims, 2 regular prims and 1 mesh object. 

All 5 objects are linked and together, they add up to an LI of 4. 

So yes, it's perfectly possible. And I would like to encourage you to experiment with it. It is often a big benefit to pick your building tools like a surgeon would pick their instruments. Every tool serves their purpose, none is "better" than the other one. Mesh is great but sometimes, a prim is better, depending on what you 're building. Sometimes a sculpty is the best choice you can make. I promise, we will look at these differences in an extra article soon. 😁

 

By the way, these rules also apply whenever you want to use ALM materials in your prim or sculpty builds. ALM materials (normal and specular textures) can significantly higher your LI when used on prims or sculpts. Like, a simple prim sphere with ALM material textures can end up with 800 LI or more (YES, I know how it sounds but it's TRUE! Check it out here!). 

Now, let's jump right into it and see what we need to know when we want to mix our prims.

Rule #1: Set your prims to Convex Hull

This is the first and foremost rule when you make a mixed linkset: ALWAYS set all prims to Physics Shape Type "Convex Hull" when you plan to link them to mesh.

To do this, select your prim, go to Features Tab and pick "Convex Hull" from the Physics Shape Type menu. 

 

This is absolutely necessary as mixed linksets can really mess up your LI when fortune does not favor you. 

By doing that, you can also already see if your LI is turning out to be a problem. It will show as soon as you have set the Physics Shape Type, so you will already get a clue if it works out or not. 

 

Caveats:

There is one downside of the "Convex Hull" trick though: 

As it will cause SL to use simplified physics, it also will ignore  all holes and hollowed shapes. You probably know this from sculpties: Even if they look as if you could walk through, their physics are one big block, so you have to set them to phantom to be able to use holes that are in it. 

This problem only affects regular prims though. Sculpties ignore all holes anyway, and mesh objects usually ignore holes, too - unless the creator cared to make custom physics for them. The good mesh creators do that when it makes sense - but the vast majority doesn't. 

 

Rule #2: Pick a very simple object as your root prim

Always try and pick either a mesh part or a very simple prim (like a box) as the root prim.

If the mesh part is not made by you, you want to take one of your prims, so it shows your name as the creator of the build. Boxes and cylinders are the simplest prims you can add (boxes are still better than cylinders though).

 

If you have the permission to upload mesh to Second Life (you need to go through an approval process on the  Second Life website), you can also create a simple mesh object for yourself with your name as the creator. In another article, I show you how to make a mesh cube for Second Life with nothing more than your viewer. 

First Troubleshooting:

If you have a very complicated prim, like a heavily tortured torus or a very detailed or big sculpt, it might shoot up your LI even though it's set to "Convex Hull". You usually see that right away on the LI of the object in the edit window - but sometimes, the actual LI needs a bit to update. Peek at the free LI on the land when you change it, this often updates much faster and will give you a direct clue if your LI goes up, down or stays the same.

If you have this troublemaker as a child prim, you can try and set it's physics shape type to "NONE" - that often fixes the problem. 

BUT...
Physics shape type NONE only works on child prims. You can not set the root prim to have no shape. If you try, you will get an error message. It's no big deal though, the rest of the build will still change to Physics Shape Type "None". Just the root prim will stay what is was before. And yes, it will stay whatever it was before, so if it was Physics Shape Type "Prim", it will still be "Prim" and this can potentially cause trouble. 

 

So this is why we want to have a prim with simple physics as the root prim: it won't cause any problems when set to "Convex Hull" and it most likely doesn't affect the linkset too much, even if we don't pay attention and have it set to "Prim". 

Note:

Physics Shape Type "None" also sets the prim to "Phantom".
This is a nice and easy way to set single objects to Phantom in a non-Phantom linkset but it only works if it doesn't mess up your LI.

Sometimes, we want to have "holes" in our builds, e.g. for doors, hallways, etc. 

Holes in prims or mesh are ignored with the simplified physics of "Convex Hull". If we want the object's physics to behave like the object looks, we have to set it to Physics Shape Type "Prim". This can cause serious trouble though, especially if we use complicated prims or ALM materials, so we'll have to be really careful with it.

Sculpted prims will always ignore holes, no matter what. If we have hollow sculpties in our linkset, we will have to make them "Phantom" in one or another way to be able to walk through them.  

In former times, there used to be scripts with a phantom hack, that allowed us to make single prims phantom within a linkset. There still are some that work, but it's often wonky and it requires a script in every prim (though the can be removed without changing the effect - but when you change the linkset, this might break.). 

Physics Shape Type "None" does exactly this thing for us. Of course, we will need objects that defines the physics then or we could just walk through the walls or fall through the floor.

Now... what if our LI is still too high?

 

1.) Search your linkset for another troublemaker - probably there is another prim that you didn't expect to cause high LI.
If in doubt, just set the whole linkset (except for the root prim) to Physics Shape Type NONE and see what happens to your LI.

2.) Check the mesh you use. Some mesh is really badly created or is uploaded with too high LoD settings, so it has a very high LI by itself. Unfortunately, there is no way to fix bad mesh inworld.

3.) Check the scale of your build. The bigger the mesh, the higher the LI and sometimes, it just needs to be a little bit smaller to lower the LI significantly (especially if the LoD of the mesh is very high!).

4.) If the LI is just a little bit higher as you would like it, you can always try to add a few more simple prims or mesh parts, like a few decorations more or something simple that enhances your build. Sometimes, the LI just rounds up and you can add quite a few more prims and still keep the LI.
Just experiment... ;)

5.) If everything fails....
Well, there are cases where there is no further option than to leave things unlinked. In this case, make 1 linkset for all mesh objects and another linkset for prims and sculpties. If you need things to be partially phantom, make a 3rd linkset for all phantom objects. You can then use a rezzer system (like Builders Buddy, for example) to make it easy to rezz your build or keep the linksets soft-linked.

 

 

 

Ok, that was it for today. I hope this helped a bit to demystify mixed linksets. 

I really want to encourage you to experiment with mixed linksets as all SL objects have their purpose and there's no reason to drop helpful tools form your toolbox only because they appear outdated or complicated. 

Please tell me about your experiences in the comments  and also let me know if you have further questions or have some more additional information about it. I would really like to know what you think. 

Have a wonderful day and I'm looking forward to hear from you,

Wolf Song