Object selection is one of the most basic and frequently used actions in any CAD software. Normally, in LusoCAD, you can work in two ways: start a command and then select the objects, or select the objects first and only then execute the desired command.
However, some users may notice that preselection suddenly stops working. If this happens, it does not necessarily mean there is a problem with the design or the software. As we saw in previous articles about system variables and the like, many behaviours in LusoCAD are controlled by variables that may have been inadvertently altered.
In this article, we will examine the main variable responsible for this behaviour and other definitions related to object selection.
Check the PICKFIRST variable
The most important variable in this case is PICKFIRST, eThis variable controls whether it is permitted to select objects before starting a command.
To check the current value, write PICKFIRST at the command line and press Enter.
PICKFIRST = 1
This is the default value.
When set to 1, users can:
- Select one or more objects
- Run the intended command
For example:
- Select a line
- Run the MOVE command
- The selected object remains active for editing
This is the behaviour expected by most users.
PICKFIRST = 0
When this option is disabled, pre-selection stops working.
In this case, it will be necessary:
- Run the command first
- Select the objects afterwards
If you cannot select objects before a command, simply change the value to 1.
2. Check the PICKAUTO Variable
Another variable related to the selection is PICKAUTO, eThis variable controls the automatic selection by window or crossing.
To check the current amount: PICKAUTO.
PICKAUTO = 1
This is the default value.
When the cursor is dragged in an empty area of the drawing, LusoCAD automatically creates a window or crossing selection.
This makes it easy to quickly select multiple objects.
PICKAUTO = 0
When this option is disabled, automatic window selections no longer work in the usual way.
If you notice difficulties when selecting groups of objects, it is worth checking this variable.
3. Check the PICKADD variable
If the problem is related to the selection of multiple objects, the variable to be analysed is PICKADD, eThis variable controls how objects are added to the selection set.
To check the current value: PICKADD
PICKADD = 1
The newly selected objects are added to the existing selection.
This makes it possible to create selection sets with multiple objects.
PICKADD = 0
Each new selection replaces the previous one.
In practice, when selecting a new object, the previously selected objects are removed from the selection.
Quick Check
If you are having trouble with object selection, confirm that the following values are set:
- PICKFIRST = 1
- PICKAUTO = 1
- PICKADD = 1
These are the settings normally used by most LusoCAD users.
Conclusion
If you cannot select objects before starting a command in LusoCAD, the most likely cause is the variable PICKFIRST to be defined for 0. However, it is also worth checking the variables PICKAUTO and PICKADD, as these influence the behaviour of window selections and multi-object selection.
With just a few seconds of checking, you can quickly restore normal selection behavior and continue working without interruption.