In Composer we have the ability to select either subassemblies or the parts within them when performing a function such as a translate. The difference is subtle but important. If we select a subassembly using the Assembly Selection methods, the translate (or other operation) is performed on the assembly actor. Any component contained within that assembly is affected. If a component is added to this subassembly (drag & drop into the subassembly), it too will automatically be affected by this function.
If we pick each individual component in an assembly and apply the function, then only those selected components are affected. If a component is added to this subassembly it will not be affected by the function that was applied earlier to the components in that subassembly. You would have to redo that same function on the added components.
In animations, using assembly selection results in fewer keys in the animation timeline which simplifies things.
To perform an assembly selection:
- Use the “Assembly Selection Mode” button in the Assembly pane.
- Hold the ALT key down while clicking on a component in an assembly.
- Click on a component in an assembly in the viewport (model window) and then press the LEFT arrow key on the keyboard.
In any of those cases, the assembly actors should highlight in blue (default colour) and a thin blue border should appear around the viewport. Also, the assembly name will be highlighted in blue in the assembly tree.
Once the assembly has been selected, apply the function you wish to perform.