A crowded molecular scene can make a simple task surprisingly difficult: locating the mesh you want to inspect, or separating it from meshes that are hidden, unselected, or named differently. In SAMSON, the mesh-specific Node Specification Language (NSL) attribute space gives you a compact way to describe which mesh nodes you want to match.
The key starting point is me. It identifies the mesh attribute space, which matches only mesh nodes. That makes expressions such as me.v useful when your intention is to query mesh visibility rather than visibility on every kind of node.
Start with a clear question
Before writing an expression, decide what you are trying to find. Are you looking for meshes that are visible? Meshes that have a material? A mesh with a particular name? Turning the task into one small question at a time helps avoid mixing up attributes that sound similar.
- Visible meshes:
me.v - Meshes that are not visible:
not me.v - Meshes with a material:
me.hm - Meshes without a material:
not me.hm - Selected meshes:
me.selected - Meshes that are not selected:
not me.selected
These are Boolean attributes: their possible values are true and false. The examples above use the short forms for visible and hasMaterial, while selected is written out in full for meshes.
Use names to narrow your search
If the mesh has a useful name, the name attribute can help you identify it. The documentation’s examples include me.n "A" and me.n "L*". The n is the short name for name, and the value is written in quotes. This gives you a practical way to express a name-based query instead of relying only on visual inspection.
For example, when you are trying to locate a mesh whose name follows a recognizable pattern, start with the documented form me.n "L*". If you know the name to search for, use the quoted-name form, such as me.n "A". The examples show the supported expression forms; consult the NSL reference if you need details about matching behavior.
Don’t confuse related attributes
The mesh attribute list includes visible, hidden, visibilityFlag, selected, and selectionFlag. They are all inherited from the node attribute space, but the reference lists them as separate attributes. If your question is specifically whether a mesh is visible, use me.v or not me.v. If you want to query the visibility flag itself, use me.vf or the explicit form me.visibilityFlag. Likewise, selection can be queried with me.selected, while the selection flag can be queried with me.sf or me.selectionFlag.
This distinction is useful when a query does not seem to answer the question you intended to ask. Rather than treating “visible,” “hidden,” and “visibility flag” as interchangeable labels, choose the exact attribute that corresponds to your task. The same applies to selection and selection flags.
A small, repeatable workflow
- Begin with the mesh scope: use the
meprefix. - Choose one attribute that describes what you need: for example,
v,hm, orn. - Use the documented short name when available, or write the full attribute name.
- For Boolean checks, use the attribute directly or negate it with
not, as innot me.h. - Check the reference for the attribute’s possible values and examples before building a more elaborate query.
Mesh attributes are inherited from the general node attribute space, so the mesh reference is also a reminder that many familiar node properties can be queried specifically for meshes. One small but important detail: selected has no short name in the mesh attribute space, so write me.selected rather than assuming a short alias.
For the complete list of mesh attributes and their examples, see the SAMSON mesh attributes reference.
Note: SAMSON and all SAMSON Extensions are free for non-commercial use. Get SAMSON.