Class and Layer: a beginner's question

[jan15]

Layers can do most of what Classes can do, plus some other things that Classes can't do, chiefly the spatial distinctions described above, and scale, and creating drawing sheets and viewports. Both have the on/off/grey/etc. options. Both can be used in both 2D and 3D work. But you don't have to use both, or either one really. They're available for your convenience.

In 2D work, Layers are like layers of drafting film, and they can't overlap. Everything on a higher layer is above and can hide anything on a lower layer.

In 3D work, a tall object on one floor can extend through the base plane of the floor above. The layers are only floor levels if you set them up that way.

Most people use Classes for the same things in 3D as in 2D, like distinguishing between plumbing fixtures, doors, furniture, etc. or distinguishing objects that you want to print all the same color, lineweight, etc. You can assign those attributes by Class but not by Layer. Objects in a Group or Symbol don't have to be all in the same Class, but they're all on the same Layer that the container object is on.

[Pat Stanford]

I have not read all of the previous threads, but let me take a shot at this.

Every object in VectorWorks has both a Layer that it is on, and a class that it is in. If you start a new document and don't change anything, objects will be drawn in the None class and on a Layer called Design Layer-1.

Layers and classes have both similarities and differences. Let's talk about Layers first.

Each design layer can be given a different scale. I like this because it allows me to draw and assign line weight that are more likely to be appropriate for the output size. Layers can also be given Z (vertical) heights so objects can be set up to stack in a 3D view. This is also very useful in an artchitectural use to allow you to reference door and window heights to a local "zero" point. You can assign each floor a different Z-height. Then when you put the windows in on the third floor, you can just set the sill height to be 3'6". It will automatically be placed at 3'6" above the layer zero point. No calculating the heights of the first and second floor to get it right. Layers can also be assigned a color. If you then turn on layer colors in the Document Preferences, all objects on each layer will display using the color of that layer. This can be very useful to make sure things are where you want them. By using Layers, you can draw objects that overlap in the proper orientation instead of spreading them out across the drawing.

What do Layers and Classes have in common? The can both be used to control visibility of objects. You can set a Layer or a class to be visible, invisible or grey. If either the Layer or the Class of an object is set to invisible, the object will not be seen in the drawing. Layers and Classes can also be used for Selection. You can set Layers and Classes to Show Active Only, Grey Others, Show Others, or Show/Snap/Modify others. Depending on the options you choose, you can pick certain parts of you drawing to select and modify the objects.

What do Classes have that Layers don't? The biggest capability that Classes offer is the ability to assign attributes (colors, hatches, line weights) to objects that are in a given class. That way when you change the attributes of the class, all of the objects can be changed at the same time. Classes also provide a way to identify objects across multiple layers.

So an Architectural example. Let's draw a three story building. You are probably going to want to have 5 Layers for the model. Basement/Foundation, First Floor, Second Floor, Third Floor, Roof. If you want to use a single file for both the model and documentation, you will probably want several more layers for Title Block, Notes, Details, Elevations, etc.

Classes in an architectural use would be used to set the type of object. Some types would include Furniture, Plumbing, Electrical, Floor, Moulding, etc. In some cases where you want to have different types of flooring, you might end up with multiple Flooring Classes (i.e Tile, Linoleum, Hardwood, Carpet1, Carpet 2). You might also want to have classes for notes or objects that should not be seen everywhere (Objects that only show in the Reflected Ceiling Plan should be in classes that can be turned off when you are looking at the plan). If you want to use the worksheet capability to count specific types of objects, classes are a great way to do this. Put the fancy carved columns into a class and then use the worksheet to count the number of objects in that classs.

Layers and Classes work together to allow you to specify what part of a model you want to see and how it will be look. They both apply to both 2D and 3D objects, so there is no differentiation there.

One object two categories it can belong to. Both effect what is visible and what it look like. As said in the earlier threads. Layers are where an object sits, Classes are the type of object it is.

I hope this helps.

Pat

[Ray Libby]

Classes are not just 2D, classes are visibility among other things, in 2D and 3D. Layer can also be visibility along with scale and layer height.

[Maccus]

OK, so if I treat Classes to be the equivalent of Objects and Layers to be construction levels I shouldn't go too far wrong.

Thanks everyone.