Organizing drawings with AutoCAD - 5 Section

22.2 Layers and Objects

If the planning of our drawings are now based on their organization by layers, then we must know how they are manipulated and what advantages they offer us when creating objects.
For example, if we decide that an already drawn object must belong to another layer, then we select it and choose its new layer from the list that is in the section of the ribbon. When you change layers, the object takes its properties. Obviously, the ideal is to draw the different objects in their corresponding layer, so you should be careful that your current layer is the one in which the objects to be created will remain. To change the layer, simply choose it from the list.
If you select an object that belongs to another layer, the list changes to show that layer, but that does not make that layer the current working layer, for that is the second button in the section.

You may have noticed that the most important layer functions are available in the drop-down list, in the Administrator window, and in the buttons on the Ribbon section. This is the case of the command that serves to block a layer, which prevents the editing of the objects it contains. In a locked layer we can create new objects, but not modify existing objects, which is a great way to avoid accidental changes.

As we explained at the beginning, we can also make the objects of a layer appear or disappear from the screen as if we were removing or adding acetates. For this we can deactivate the layer or disable it. The effect on the screen is apparently the same: the objects of that layer are no longer visible. However, internally there is a difference of consideration, the objects of the deactivated layers become invisible, but their geometry is still considered for the calculations that Autocad does when it regenerates the screen after a Zoom or Regen command, which redraws everything. On the other hand, rendering a layer unusable not only makes the objects it contains invisible, but it also stops being considered for those internal calculations. It is as if these objects cease to exist, even while the layer is unused.
The difference between both procedures is not really relevant in simple drawings given the speed at which internal calculations can be made. But when a drawing becomes very complex, rendering it useless can be practical if we are going to do without some layers for a long time, because we save calculations and, therefore, time to regenerate the drawing on the screen. However, if we disable layers with thousands of objects only to be invisible for a moment and then reuse them, we force Autocad to perform all regeneration calculations, which may take a few minutes. In those cases it is better to deactivate.

22.3 Layer filters

Those who work in any area of ​​engineering or architecture, know that the blueprints of large projects, such as a large building or a large engineering installation, can have tens or hundreds of layers. This implies a new problem, as the selection of layers, their activation or deactivation or, simply, the change from one to another could mean a huge search job among those hundreds of names.
To avoid this, Autocad also allows to discriminate layers for use by applying filters. This idea is similar to the object filters that we saw in the 16 chapter. So we can apply a filter to work only with groups of layers that have certain properties or a certain common name. In addition, it is also possible to create the criteria with which the layers will be filtered and save them for future occasions.
These filters, of course, can be used from the Layer Properties Manager. When we click the button to generate new filters, the dialog box where we can indicate the name of the filter and the selection criteria of layers arranged in columns appears. In each column, we must specify the characteristics of the layers to be displayed. A simple example would be to select those layers whose line color was red. Thus, it would be enough to use any combination of properties in the columns to filter the layers: Line type, thickness, layout style, by name (using wildcards), by state, if they are disabled or blocked, and so on.

In fact, this style of filtering the layers is what, in databases, is called "query by example". That is, in the columns we put the layer properties that we want, only those that meet those requirements are presented.
On the other hand, it is also possible to filter layers using their names, for this we create filtering criteria using wildcard characters.
For example, suppose we have a drawing with the following layers:

1 Floor Walls
2 Floor Walls
3 Floor Walls
4 Floor Walls
1 Electrical Installation-a Floor
Floor 1 Electrical Installation-b
2 Electrical Installation-a Floor
Floor 2 Electrical Installation-b
3 Electrical Installation-a Floor
Floor 3 Electrical Installation-b
4 Electrical Installation-a Floor
Floor 4 Electrical Installation-b
Floor 1 Installation Hydraulic and sanitary
Floor 2 Installation Hydraulic and sanitary
Floor 3 Installation Hydraulic and sanitary
Floor 4 Installation Hydraulic and sanitary

In order for Autocad to filter several layers, so that only those of the electrical installation can be seen, we can indicate wildcard characters in the “Layer name” section by writing:

Floor # Installation E *

Maybe many of these characters seem familiar to create filters, in fact they are the same as those used in the MS-DOS operating system with commands like DIR in ancient times, when Aragon fought Sauron so that the hobbit could destroy the ring and the computers depended on some of Gandalf's magic. It is said that in those years the Microsoft software was rather the work of orcs.

But let's look at the characters used to create the above filter. The symbol # is equivalent to any individual numeric character, so when applying the filter, the layers that have numbers from one to four appear in that position; the asterisk substitutes for any string of characters, so putting it after the “E” removes all other layers that don't have “Electric” in their name. This filter would also have worked as follows:

Floor # Electrical Installation- *

The asterisk and # sign are not the only characters that are used to create layer filters. The following list presents some of common use:

@ (at) In its position there can be any alphabetic character. In our
For example, the 2 Floor Installation - @
result 2 layers.

. (dot) Equals any non-alphanumeric character, such as dashes,
ampersand, quotes or spaces.

? (interrogation) Can represent any individual character. For example,
would it be the same to put Floor # M * than, Piso? M *

~ (Tilde) Creates an exclusion filter if used at the beginning of the mask.
For example, if we put ~ Floor # Inst * will exclude from the selection
to all layers of the hydraulic and sanitary facilities.

However, it is also possible to create groups of layers without necessarily having elements in common, such as line or color characteristics or certain characters in their name and which therefore have to be expressed in terms of a recorded filter.
Group Filters are groups of layers that the user selects on his own free will. To create one, click the corresponding button, give it a name and simply drag the layers that we want to be part of the group from the list on the right. In this way, when you click on the new filter, the layers that we have integrated will appear.

Consider that creating layer filters and group filters has no effect on the layers themselves, much less on the objects they contain. So you can create as many branches as necessary in your tree view with the idea of ​​always having a long list of layers organized. This will hardly regain control.