Blender For Dummies. Jason van Gumster

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      There’s another way. When you add a new primitive while in Edit mode, all the elements of your new primitive are selected, and nothing from your original object is selected. If only there were a command that would let you break this primitive away from the container object and into an object of its own. Fortunately, there is. While in Edit mode, choose Mesh ⇒ Separate ⇒ Selection, and your new primitive is separated into its own object. You can also access this function by hotkey (P ⇒ Selection).

      Tab back into Object mode and select your new object. Its origin is located in the same place as its original object’s origin. To put the origin of your new object at its actual center, choose Object ⇒ Set Origin ⇒ Origin to Geometry in the 3D Viewport’s header. This Origin to Geometry operation checks the size of your object and calculates where its true center is. Then Blender places the object’s origin at that location.

You can also specify that the object’s origin be placed wherever your 3D cursor is located by choosing Object ⇒ Set Origin ⇒ Origin to 3D Cursor.

      A third option is similar to Origin to Geometry, but it moves the object’s content rather than the origin itself. Perform this operation by choosing Object ⇒ Set Origin ⇒ Geometry to Origin.

      As expected, you can also join two objects of the same type into a single object. To do so, select multiple objects. You can practice using the Box Select or Lasso Select tools, or you can simply Shift+click objects to add them to your selection. The last object you select is considered your active object and is the object that the others join into. With your objects selected, join them by choosing Object ⇒ Join from the 3D Viewport’s header or by using the Ctrl+J hotkey combination.

      

You can join objects of the same type only. That is, you can join two mesh objects, but you can’t join a mesh object with a curve object. It’s possible to get around this by converting objects to be the same time (Object ⇒ Convert to). However, using parenting or collections (discussed later in this chapter in the section “Discovering parents, children, and collections”) may be more appropriate.

      UNDERSTANDING THE DIFFERENCE BETWEEN JOINS AND BOOLEANS

      This is a bit of a terminology thing. If you’ve never worked in 3D computer graphics before, you might expect that a join operation on two objects would result in a single, connected mesh. That’s not quite how it works. Earlier in this chapter, I explain that an object can consist of both linked and unlinked elements. There’s no requirement that, for example, all the vertices in a mesh object are linked by faces and edges. When you join two separate objects using Object ⇒ Join, you’re really just bundling them into the same object datablock. You aren’t changing any of the component mesh data.

      To actually merge meshes into a single linked unit, you need to either

       Edit the mesh data manually — merging vertices and creating new edges and faces as necessary.

       Use a Boolean — an operation that does a logical (for example, and, or, intersection) combination of two meshes.In Blender, Booleans are done with a modifier. Modifiers are covered in more detail in Chapter 5.

      Creating duplicates and links

      In the section “Working with linked vertices,” earlier in this chapter, an example involved duplicating your selected vertices by using Mesh ⇒ Duplicate. As you may expect, this operation also works in Object mode (the hotkey is the same — Shift+D — but the menu item is slightly different at Object ⇒ Duplicate Objects). This duplication method is great if you intend to take an existing object and use it as a starting point to model another, more individualized object by tweaking it in Edit mode. However, suppose that you want your duplicated object to be identical to the original in Edit mode. And wouldn’t it be nice if, when you do go into Edit mode, your changes happen to the original as well as to all the duplicates? For duplicated objects that you have to edit only once, you want to use the power of linked duplicates. Linked duplicates are objects that share the same internal datablocks.

      

Linking objects, in this case, is different from the linked vertices described earlier in this chapter. The fact that the same word is used in a couple different ways can be a bit confusing, but there’s a mnemonic that can help you keep things straight:

       Linked vertices (as described earlier in the chapter) are specific to Edit mode.

       Linked objects (as described in this section) are specific to Object mode.

      Linking data between objects

      Linked duplicates are similar to what other programs call instance copies. The process to create a linked duplicate is pretty straightforward:

      1 Select the object you want to duplicate.

      2 With the object selected, choose Object ⇒ Duplicate Linked from the 3D Viewport’s header or use the Alt+D hotkey combination.From here, the behavior is just like regular duplication.The object is automatically in grab mode.

      3 Place the object with your mouse and confirm its new location by left-clicking or by pressing Enter.

You can use a few other methods to verify that this duplicated object is, in fact, a linked duplicate. The easiest way is to tab into Edit mode on the original object or on any of the duplicates. When you do, all the linked objects appear to go into Edit mode, and any changes you make here automatically update all the other objects immediately. Figure 4-9 shows three linked duplicates of Suzanne being simultaneously modified in Edit mode.

      FIGURE 4-9: Editing duplicated Suzannes!

      UNDERSTANDING DATABLOCKS: FUNDAMENTAL ELEMENTS IN A BLENDER FILE

      To really understand how data linking works in Blender, it’s essential to know how datablocks work. A simple and obvious definition of a datablock is that it’s literally a block of data. However, there’s obviously more to it than that. Datablocks are used throughout both Blender’s interface and its internal structure, so understanding how they work and how you can take advantage of them goes a long way to understanding Blender itself. Nearly every critical element in Blender is stored in a type of datablock, from workspaces and scenes to objects and animations.

      Not only is a datablock a handy way to store information, but it also allows Blender to treat this information like a database. In particular, you can link datablocks and let them share information. As an example, say that you’ve created an excellent wood material, and you want to have two objects — a table and a chair — look like they’re both made of the same wood. Well, rather than re-create that exact same material for each object, you can simply link both object datablocks to the same material datablock. Your computer uses less memory, and, more importantly, you have less work to do. And because datablocks are used throughout Blender, СКАЧАТЬ