The REGION command is used to convert closed objects such as polylines, polygons, circles, ellipses, closed splines, and donuts into two dimensional regions. After we create a region, we can then modify it using various three dimensional tools.
The EXTRUDE command is used to create 3D solid or surface by extruding the dimension of selected object. For example, a circle can become a cylinder, a line can become a 3D plane, and a rectangle can become a box.
The system variable that controls the cumulative selection is PICKADD, the initial value for PICKADD is 2, which means the PICKADD is on; when the value is 0 or 1, the PICKADD is off, which means the previously selected objects are removed from the selection set.
Imagine that we have selected some objects and are ready to edit them but cancel the selection by mistake. Can we get the selection back? Just execute the CHANGE command, and when we are prompted to select object, type P and then press Enter, we will get the canceled selection back.
The background color of different versions of CAD system doesn’t remain unchanged over the years. However, the settings of different colors may be confusing for some beginners, so let’s explore the settings of color in your CAD system together.