Читать книгу Blender For Dummies - Jason van Gumster - Страница 83

Ngons are a fantastic help when modeling 3D meshes. However, there are still some limitations. For example, an ngon cannot currently have a hole in it — not on its own, at least. As the figure shows, to get a hole, you need to have two faces. There need to be edges that connect from the inner ring of vertices to the outer ring.

As mentioned earlier in the chapter, it’s best to think of ngons as a process tool. On any mesh that’s likely to be used in animation (like a character model) or included in real-time environment like a video game, the finished mesh should be composed of only tris and quads. An exception to this rule of thumb might be for architectural models or models intended to be rendered as still images. Because those meshes won’t be deformed by something like an armature or a lattice and they don’t have to work in a game engine, often you can get away with leaving ngons in them.

In 3D, extrusion follows a similar concept, except you don’t have to create the hole to extrude through. Instead, that shape is determined by your selection, and you can extend that selection in any direction. Follow these steps to extrude:

1 Select the object you want to edit.

2 Tab into Edit mode or switch to the Modeling workspace.

3 Select the vertices, edges, or faces you want to extrude.Use any of the selection methods listed in the previous section.

4 Extrude your selection in one of several ways:Vertex, Edge, or Face menus in the 3D Viewport’s header.Quite sensibly, because the Extrude operator is used so frequently, it’s the first choice in each of these menus. Do note that Blender will extrude only the components associated with the menu you use. So even if you have a whole face selected, if you choose Vertex ⇒ Extrude Vertices, Blender extrudes only the vertices in your selection rather than the whole face. Most frequently, you’ll probably want to use Face ⇒ Extrude Faces. Extrude tool.When you tab into Edit mode, the Toolbar on the left side of the 3D Viewport expands with a whole mess of additional tools you can choose from. The first of these added tools, of course, is the Extrude tool. Actually, that button is the home of a few different extrusion tools, but I cover that later in the chapter. The default tool for extrusion is Extrude Region, and it has an icon like the one to the left. When you choose this tool, a yellow gizmo appears on your mesh: a plus sign in a circle with a line to your selection. Left-click and drag that gizmo to extrude your selection in the direction it’s pointing.E hotkey.The E hotkey is by far the fastest way to extrude in Blender. When you press E, your selection is extruded and Blender automatically puts you in grab mode on your newly extruded parts. This means all your constraint hotkeys still work as well. Want to extrude your selection along the global X-axis? Press E ⇒ X and off you go! If you have a face selected, your new extrusion is constrained to move only along its normal. If you don’t want this constrained behavior, middle-click your mouse (without moving it) and the constraint is removed, allowing you to freely move your extrusion around.

There are advantages and disadvantages to Blender’s extrude operator leaping directly into grab mode when you use the hotkey approach. The advantages are that you have all the transform functionality, such as axis-locking, snapping, and numerical input immediately available to you. The disadvantage is that, because of this autograb behavior, if you cancel the operation by right-clicking or pressing Esc, the newly extruded vertices, edges, or faces are still there, just located in exactly the same place as the vertices, edges, or faces that they originated from.

For this reason, if you cancel an extrude operation, make sure that your duplicate vertices, sometimes called doubles, are no longer there. A quick way to check is to press G after you cancel your extrusion. If it looks like you’re extruding again, you have doubles.

You can get rid of doubles in a variety of ways:

 If the canceled extrusion operation was the last thing you did, undo it by pressing Ctrl+Z. This solution usually is the quickest.

 If you still have the doubles selected, delete them. You can activate the delete operation with hotkeys (X or Del), choosing to Mesh ⇒ Delete ⇒ Vertices in the 3D Viewport’s header. If you use the Delete hotkey, you see a menu where you decide what elements of the mesh you want to delete. In this case, you choose Vertices. The disadvantage of this method is that it also removes the faces created by those vertices.

 If you’re unsure whether you have doubles from previous canceled extrusions, use Blender’s special Merge Vertices function:In Edit Mode, select all by choosing Select ⇒ All from the 3D Viewport’s header or pressing A.Right-click in the 3D Viewport and choose Merge Vertices ⇒ By Distance.With this operator, Blender removes all doubles from your mesh. You can also find this option in Vertex ⇒ Merge Vertices ⇒ By Distance in the 3D Viewport’s header, as well as with the Alt+M hotkey.

If you have Blender’s mesh auto-merge feature enabled (it’s disabled by default, but can be enabled in the Active Tool tab of the Properties editor within the Options panel), you might expect that duplicate vertices automatically are removed/merged if you have a canceled Extrude operation. This isn’t the case. Those extruded vertices will remain in place until you move them, so don’t assume that you’re automatically safe from having doubles when auto-merge is enabled.

Looking at the Toolbar, if you click and hold on the Extrude tool’s icon, you have more than one Extrude tool available to you. Your choices are as follows:

  Extrude Region: The default Extrude tool is Extrude Region, and it’s the only one that currently has a gizmo associated with it. It works exactly as described earlier in this section. Click the gizmo to extrude your selection. Once extruded, you can tweak your extrusion’s position and rotation using regular transform tools.

  Extrude Along Normals: Every component in a mesh has a normal, an imaginary line that sticks out orthogonally from that vertex, edge, or face. This tool is most useful when you have multiple faces selected in your mesh. It keeps the components of your selection joined like with the Extrude Region tool, but each face in the new extrusion moves along its own normal. To use this tool, just click and drag in the 3D Viewport and your selection will extrude accordingly. If you enable the Offset Even check box in the Active Tool tab of the Properties editor, this extrusion tool is very helpful for architectural and hard surface modeling. Chapter 5 has more on normals and the different approaches to modeling.MODELING ORGANICALLY WITH PROPORTIONAL EDITINGOften, when you’re modeling organic objects or objects with smoothly curved surfaces, such as characters, creatures, or sports cars, you may find yourself pushing and pulling a bunch of vertices to obtain that smooth surface. You can simplify this process by using Blender’s Proportional Editing feature. If you come from another 3D package, you might recognize proportional editing as being similar to the soft select feature. You activate proportional editing by left-clicking the Proportional Editing button, which looks like two gray concentric circles in the 3D Viewport’s header. The hotkey for this operation is O. Now when you perform a transform operation, a circle appears around your selection. Your transformation influences any vertices that are within this circle with a gradual falloff.You can adjust the influence circle used by proportional editing by scrolling your mouse wheel or pressing Alt+Numpad Plus (+) and Alt+Numpad Minus (–). Additionally, you can control how gradual the falloff is by using the Proportional Editing Falloff pull-down menu next to the Proportional Editing button in the 3D Viewport’s header, or by choosing one of the options that appears in a pie menu when you press Shift+O. The Proportional Editing feature in Blender has one more useful option. On complex meshes, you may want to use proportional editing on one set of vertices that are connected to each other, but not to other nearby vertices in the same mesh. For example, say that you’ve modeled a character and her hand is at her side near her leg, and you’d like to smoothly edit her hand and pull it away from the leg without having to gradually adjust the vertices of the arm. Proportional editing is the perfect tool for this job. However, when you try to use proportional editing as described in the previous paragraphs, other leg vertices are within the influence circle, and you end up moving those unintentionally. Wouldn’t it be great if proportional editing could understand that you only want to move the hand? Well, I have good news: It can! Expand the Proportional Editing Falloff pull-down menu in the 3D Viewport header and enable the Connected Only check box. Alternatively, press Alt+O. With the Connected Only option enabled, proportional editing adjusts only vertices connected to each other within its influence area. Neat, huh?Proportional editing works in Object mode as well. This capability can be really handy, but it can sometimes yield undesirable results if you want to use this feature only while in Edit mode. For this reason, double-check your 3D Viewport’s header before performing a transformation to see whether proportional editing is enabled.

  Extrude Individual: The Extrude Individual tool works like Extrude Along Normals, but your extruded components aren’t connected as a cohesive unit. Instead, in the case of faces, each face in your selection extrudes on its own along its own local normals.

  Extrude to Cursor: This tool gives you the fastest way to make a long series of extrusions. Say you’re modeling tree branches or the profile of a wine glass. The Extrude to Cursor tool is the way to go. Simply click in the 3D Viewport and your selection extrudes right to that point. If you hold down your mouse button, you can tweak the position of your extrusion as you go. Working this way is particularly useful when you’re doing a series of extrusions, one right after the other, such as when you’re roughing out a shape by “drawing” with vertices and edges. Technically, this tool’s feature is also available outside the tool system. While in Edit mode, if you Ctrl+right-click in the 3D Viewport, whatever you have selected is extruded to that location.

The Blender 27X keymap has a wide assortment of hotkeys for quickly accessing these extrude operators without using the Toolbar; however, most of those hotkeys are disabled in the new default keymap. Of course, you’re welcome to add your own hotkeys and add to the Quick Favorites menu to speed up your own workflow.

For some simple examples of how to make a model using the extrude operator, visit the tutorials I’ve placed on www.blenderbasics.com.