Layers

Layers essentially are a method for organizing and grouping entities within a project. Objects are automatically placed onto layers when they are generated, and then can be moved from one layer to another through the Layers palette located, by default, within the Palette dock to the right of the project window. It is through this palette or its contextual menu (right-click) that layers are created, managed, and deleted.

 

layers_palette.png
The Layers palette

The first row of the Layers palette (underneath the title bar) is a horizontal headers bar that contains five columns. They are (from left) Active Layer, Visibility, Selectability, Snapability, and Name. Each of these columns are as follows:

 

Active Layer: The red dot (Cic_8012.ENU.png) indicates the active layer. To make an inactive layer active, simply click in the column of the desired layer. Only one layer is active at any given time. The active layer is where new objects are placed when you generate them.

 

palettes_context_menu.tiff
Layers context menu.

The second, third, and fourth columns control three layer attributes. These can be applied individually, or simultaneously to all layers with one click in the header bar. The attributes of the layers apply equally to all the layers independently of whether they are active or not.

Visibility: Clicking within this column toggles the respective layer and its objects between three states: visible (Cic_8004.ENU.png), ghosted (Cic_8005.ENU.png), and invisible (Cic_8006.ENU.png).

 

Selectability: Clicking within this column locks (Cic_8002.ENU.png) or unlocks (Cic_8003.ENU.png) the respective layer. If the layer is locked, objects within the layer cannot be selected (picked).

 

Snapability: Clicking in this column determines whether the system will snap to the entities of the respective layer, when one of the object snaps is active. It has two states: snapable (Cic_8007.ENU.png) and not snapable (Cic_8008.ENU.png).

At the end of the horizontal header bar are the New Layer and Options buttons, as follows:

 

New Layer: This button (Cic_8029.ENU.png) creates a new layer with a single click.

 

Options: Clicking on this button (Cic_8011.ENU.png) invokes the palette’s contextual menu that is also accessible by right-clicking anywhere inside the palette.

 

A new project contains a single active layer which bears the default name “Layer 1.” It is visible, unlocked, and snapable by default. Layers created thereafter sequentially follow the same naming convention (Layer 2, Layer 3, etc.), however, the user is able to name them in the Layers palette as they are created.

 

As stated previously, objects are automatically placed onto the active layer from the time they are generated, and furthermore, can be moved from layer to layer in a variety of ways. One way is to drag the layer name (from the Layers palette) onto the object itself. If for example, we have a cube that is created on Layer 1 and we want it on Layer 2, all that is required is dragging the Layer 2 name onto the cube in the project window.

 

Another method is through the Attributes tab in the Pick Tool Options palette. With the Pick tool click on an object. This invokes the Pick Tool Options palette, which includes information about the object. One piece of information displayed in the Attributes tab is what layer the object is on. This is shown in a pull-down menu that contains all the currently existing layers. Selecting another layer name moves the object to that layer.

 

Layer Grouping

layer_grouping_ex1.pnga
 
layer_grouping_ex2.pngb
Layers palette with (a) both groups folded, and
(b) both groups unfolded.

Layers can function independently, or as part of a group. Choosing New Group from the Layers palette context menu (right-click in the palette or the (Cic_8011.ENU.png) button) creates a layer group. When the new group is created, it is empty (contains no layers). Clicking and dragging an existing layer onto the group name will move the layer into the group. The contained layers, or children, can be hidden or exposed depending on the direction of the triangle appearing to the left of the group name, or parent. Clicking on the triangle toggles this option. Layers can be removed from the group by dragging them outside of the group.

 

Layer Attributes dialog

Double-clicking on a layer name or selecting Edit... from the context menu (right-click) invokes the Layer Attributes dialog for that layer. Here, the layer name can be changed along with other attributes including those discussed previously (Visibility, Selectability, and Snapability).

 

Override Attributes: In this category, you are able to override object level attributes. This is accomplished by selecting the check box to the front of the attribute name. For example, if the Material attribute is turned on, all objects on the layer will be displayed with the material shown to the right, regardless of the object material. Other attributes include the ability to override whether objects on that layer will cast shadows, receive shadows, are rendered in wire frame or as a shaded surface, or if smooth shading is applied. Clicking the All button at the bottom of the category selects all these attributes simultaneously.

 

layer_attributes_dialog.png
The Layer Attributes dialog.
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