This excerpt is from Roland Hess’ Blender Foundations. Here Hess explores use of the sculpting tools in Blender as an alternative to traditional 3D modeling techniques. Comeback for a great excerpt from Roland’s newly published Blender Production later this month.
An Alternative to Traditional Modeling
In addition to modeling in Edit mode, Blender has integrated sculpting tools. The sculpting workflow allows you to work with a mesh as though it were clay—carving details, pushing and pulling the surface, imprinting it with textures—all with an intuitive, brush-based interface. The two main uses for sculpting lie in detailing and adjusting existing models, and creating new forms from scratch.
Basic Sculpting Tools
Figure 8.1 shows our character’s head mesh (created from exercises in the book), with Subdivision modifier level 1 applied to it, raising the density of the mesh. On the 3D view header, you’ll see a new mode: Sculpt. In the tool shelf are the sculpting tools. As sculpting uses the same brushlike interface as weight and projection painting, several of the tool shelf panels directly related to brushing should already be familiar.
While sculpting, the standard paint tool shortcuts apply in the 3D view. The F key interactively changes brush size. Ctrl-F changes brush strength. LMB drag executes whichever sculpting tool is selected (i.e., you “paint” with these tools just like a regular brush). Holding down the Shift key while painting reverses the effect of the tools, as we’ll see in a bit. Let’s run down the different sculpting tools, with gratuitous examples on the head.
● Draw: “Draws” a raised path on the mesh, as shown in Figure 8.2. Holding down the Shift key cuts into the mesh.
● Smooth: Evens out local geometry.
● Pinch: Gathers any geometry within the brush area toward the center of the brush. Holding down the Shift key pushes geometry away from the brush center.
● Inflate: Kind of like Draw, but this brush blows everything up like a balloon, as shown in Figure 8.3.
● Grab: Like an interactive G-key grab tool. Use it to LMB drag portions of the mesh around.
● Flatten: “Squashes” geometry toward the center of the model.
● Clay: Builds the mesh up as though with layers of clay.
Shaping Existing Models
One of the techniques for generating a head was to start with a default head structure and push it around to match reference images. While you can do this in Edit mode using the O-key Proportional Edit Falloff (PEF) technique, a more intuitive way to work is with the sculpting Grab brush.
To use this technique, select the model and enter Sculpt mode using the mode selector on the 3D view header. While in Sculpt mode, the standard view transformation tools are available (MMB rotate, Shift-MMB pan, and mouse wheel to zoom). Make sure the Grab tool is selected in the tool shelf. Now, just LMB grab a portion of the mesh and drag it around. Since sculpting doesn’t work in Wire-frame display mode, you can’t see the reference image through the mesh like you can while hand editing. For that reason, it isn’t the best choice if you’re trying to exactly match a reference. However, there usually comes a time when modeling from a reference when you have to “let go.” You’ve hit the reference as closely as you can from a technical standpoint, but when you go into Camera view and hit Render, it lacks life.
That’s when you pull out the sculpting tools. Put the reference out of your mind, and try to think of the current 3D version as the original. I’ve found the sculpting Grab tool to be a much more intuitive way of doing the final tweaks on a model than working in Edit mode.
While you’re doing this, here are some hints. First, the Grab tool moves geometry in the plane of the view. Figure 8.4 shows this. The Camera view that is seen is represented by a plane. Grab sculpting from the view on the left will move geometry only within the plane. It will not go “into” or “out of” the display plane. So, if you want to pull a cheek away from the face to make it a bit rounder, you will have to find a view like the one in Figure 8.5 in order to so. This is one of those things that sounds complicated, but is fairly intuitive once you start actually doing it.
Second, the size of the brush on screen is important. A brush will affect whatever falls inside its boundaries. So, the same “size” brush will affect a different amount of geometry when zoomed in as it does when zoomed out. With the entire head within your view, you can easily change the whole shape at once with a large brush.
Third, the controls in the Options section of the tool shelf can save you a lot of time. When working on something like a face, enable X Symmetry so that changes made to one side of the head show up on the other side as well. Of course, you might want to sculpt asymmetrically as a final pass on your model to make it more lifelike. No one is perfectly symmetrical.
Using the Grab tool to alter your existing models can add a nice organic touch to an otherwise rigid structure. In fact, we deal with adding different morphable shapes to our face in the book – we use Grab sculpting to do it.
By Roland Hess, working with graphics and imaging software for over 20 years, Roland is the leading expert for Blender software. As one of a handful of people involved with Blender who is both an active user of the software as well as one of the developers, he brings a unique perspective to Blender instruction that helps to bridge the difficult gap between technical knowledge and artistic endeavor. Hess wrote: Animating with Blender for Focal 2009, and The Essential Blender, No Starch, 2007