In basic meshes, everything is built from three basic structures: Vertices, Edges and Faces. (We're not talking about Curves, NURBS, and so forth here.) But there is no need to be disappointed: This simplicity still provides us with a wealth of possibilities that will be the foundation for all our models.

Vertices

A vertex is primarily a single point or position in 3D space. It is usually invisible in rendering and in ObjectMode. (Don't mistake the center point of an object for a vertex. It looks similar, but its bigger and you can't select it.)

To create a new vertex, change to EditMode, hold down CTRL, and click with the LMB. Of course, as a computer screen is two-dimensional, Blender can't determine all three vertex coordinates from one mouse click, so the new vertex is placed at the depth of the 3D cursor 'into' the screen. Any vertices selected previously are automatically connected to the new one with an edge.

Edges

An edge always connects two vertices with a straight line. The edges are the 'wires' you see when you look at a mesh in wireframe view. They are usually invisible on the rendered image. They are used to construct faces. Create an edge by selecting two vertices and pressing FKEY.

Faces

A Face is the most high level structure in a mesh. Faces are used to build the actual surface of the object. They are what you see when you render the mesh. A Face is defined as the area between either three or four vertices, with an Edge on every side. Triangles always work well, because they are always flat and easy to calculate.

Take care when using four-sided faces, because internally they are simply divided into two triangles each. Four-sided faces only work well if the Face is pretty much flat (all points lie within one imaginary plane) and convex (the angle at no corner is greater than or equal to 180 degrees). This is the case with the faces of a cube, for example. (That's why you can't see any diagonals in its wireframe model, because they would divide each square face into two triangles. While you could build a cube with triangular faces, it would just look more confusing in EditMode.)

An area between three or four vertices, outlined by Edges, doesn't have to be a face. If this area does not contain a face, it will simply be transparent or non-existent in the rendered image. To create a face, select three or four suitable vertices and press FKEY.

In EditMode there are three different selection modes.

See Figure 6.4, “EditMode selection menu.” for menu.

Almost all modification tools are availiable in all three modes. So you can Rotate, Scale and Extrude etc. in all modes. Of course rotating and scaling a single vertex will not do anything useful, so some tools are more or less applicable in some modes.

Figure 6.4. EditMode selection menu.

You can also enter the different modes by selecting one of the three buttons in the toolbar. See Figure 6.5, “EditMode selection buttons. Vertices, Edges and Faces modes from left to right.”. Using the buttons you can also enter mixed modes by SHIFT-LMB clicking the buttons.

When switching modes, from Vertices to Edges and from Edges to Faces, the selected parts will still be selected if they form a complete set in the new mode. For example, if all four edges in a face are selected, switching from Edges mode to Faces mode will keep the face selected. All selected parts that do not form a complete set in the new mode will be unselected.

See Figure 6.6, “Vertex mode example.”, Figure 6.7, “Edge mode example.”, Figure 6.8, “Face mode example.” and Figure 6.9, “Mixed mode example.” for examples of the different modes.

Figure 6.5. EditMode selection buttons. Vertices, Edges and Faces modes from left to right.

Figure 6.6. Vertex mode example.

Figure 6.7. Edge mode example.

Figure 6.8. Face mode example.

Figure 6.9. Mixed mode example.

Most simple operations from ObjectMode (like selecting, moving, rotating, and scaling) work identically on vertices as they do on objects. Thus, you can learn how to handle basic EditMode operations very quickly. The only notable difference is a new scaling option, ALT-S which scales the selected vertices along the direction of the normals (shrinks-fattens). The truncated pyramid in Figure 6.10, “Chopped-off pyramid”, for example, was created with the following steps:

Figure 6.10. Chopped-off pyramid

One extra feature for EditMode is the Mirroring tool. If you have some vertices selected and you press MKEY you will be presented with a Menu containing nine options. You can select from these to mirror the selected vertices with respect to any of the X, Y or Z axes of the Global, Local, or Viewing reference.

One additional feature of EditMode is the CircleSelect mode. It is invoked by pressing BKEY twice instead of only once, as you would for BorderSelect. A light grey circle is drawn around the cursor and any LMB click selects all vertices within. NUM+ and NUM- or the MW, if any, enlarge or shrink the circle.

All operations in EditMode are ultimately performed on the vertices; the connected edges and faces automatically adapt, as they depend on the vertices' positions. To select an edge, you must select the two endpoints or either place the mouse on the edge and press CTRL-ALT-RMB. To select a face, each corner must be selected.

EditMode operations are many, and most are summarized in the Editing Context Buttons window, accessed via the ( ) header button or via F9 (Figure 6.11, “Edit Context.”). Note the group of buttons in the Mesh Tools 1 Panel:

Figure 6.11. Edit Context.

With WKEY you can call up the "Specials" menu in EditMode (Figure 6.12, “Specials Menu.”). With this menu you can quickly access functions which are frequently required for polygon-modelling.

Figure 6.12. Specials Menu.

Many of these actions have a button of their own in the Mesh Tools Panel of the Edit Buttons Window (Figure 6.11, “Edit Context.”). The Remove doubles threshold can be adjusted here, too.

Blender has a global undo system, giving full multiple level undo capabilities in all areas of Blender. Exceptions are: Edit mode Armature, and Fileselect, Audio and Oops windows.

The new global hotkey for undo is CTRL-Z, and CTRL-SHIFT-Z for redo.

Mesh undo works in the background saving copies of your mesh in memory as you make changes. Pressing the UKEY in mesh EditMode reverts to the previously saved mesh, undoing the last edit operation (Figure 6.13, “Undo and Redo”).

Undo operations are only stored for one mesh at a time. You can leave and re-enter EditMode for the same mesh without losing any undo information, but once another mesh is edited, the undo information for the first is lost.

Figure 6.13. Undo and Redo

Pressing SHIFT-U re-does the last undo operation (Figure 6.13, “Undo and Redo”). Pressing ALT-U brings up the Undo Menu (Figure 6.14, “Undo Menu”). This lists all the undo steps by name so you can quickly find your way back to a known good point in your work. The ALT-U menu also contains the option All Changes. This option is more powerful than merely pressing UKEY repeatedly, and will reload the mesh data as it was at the beginning of your edit session, even if you have used up all your undo steps.

Figure 6.14. Undo Menu

Edit undo can be memory intensive. A mesh of 64,000 faces and verts can use over 3Mb of RAM per undo step. If you are on a machine that is strapped for RAM, in the User Preference Window, under Edit Methods, there is a NumButton for determining the maximum number of undo steps saved. The allowable range is between 1 and 64. The default is 32.