Blender 2.5 Character Animation Cookbook: With this highly focused book you’ll learn how to bring your characters to life using Blender, employing everything from realistic movement to refined eye control. Written in a user-friendly manner, it’s the only guide dedicated to this subject.

Open the file 001-Orientation.blend from this book's support files. You'll see a hand model with four of its finger bones already set. I've let the ring finger for you to rig, like in the next screenshot:

Position your 3D cursor where the first finger bone should be created: select your mesh, enter the Edit Mode (Tab), select a vertex or group of vertices at the base of the finger and press Shift + S. Choose Cursor to Selected.

Go back to Object Mode (Tab), select the armature, enter its Edit Mode (Tab) and press Shift + A to add a new bone under the cursor location.

Now you just move the tip of this bone until the finger's first joint and extrude the bone two times, right? WRONG!

Extruding bones is just what one would normally do in order to create a bone chain, but that brings to our new bones some unwanted rotations.

Select the tip of your bone and move (press the G key) it until the tip of the finger, as seen in the next screenshot:

Select your entire bone, open the Specials menu (press the W key), and choose Subdivide. Select one of the bones and repeat this process.

Move (press the G key) the joints to the appropriate places of the finger, and the orientations will be consistent. Note that the X axis of each bone is always pointing toward us, while the other bones on the hand have their Z axes pointing up. We need them all consistent.

Select the bones you have just created, press Ctrl + R, and type 90. This will correct their rotations, making their Z axes point toward us (check the Axis conventions section at the end of this recipe to know more about this).

Select the hand mesh, hold Shift, select a bone, and press Ctrl+ P. Choose With Automatic Weights to get a basic deformation on the hand.

Now you can rotate the bones under their local X axis (R + X + X) to see what happens.

Position the 3D cursor on the base of the tail, with a left mouse click in the 3D View, as seen in the next screenshot:

Press Shift + A and select Armature | Single Bone to create one bone which extends from the base to the tip of the tail. Enter in Edit Mode (press Tab), select its tip, and move (press G) it to the tip of the tail.

Select the bone, press W, and select Subdivide. Repeat this two more times in order to get eight bones. Select each joint and move (press G) it so it fits the tail nicely.

Select all the bones (the A key), press Ctrl + R, and type 90 so their orientation is set with their X axes pointing towards us. The X local axis will be the default to the front or back rotation.

Refer to the recipe called Defining good orientations for your bones if in doubt. You should end up with something similar to the next screenshot, showing the front and side views:

Still in Edit Mode, set the bones' names using the Properties panel (press the N key). For their names, use a prefix such as D_, which stands for "Deformation". That's the role of these bones: they're responsible for deforming our mesh. Good names can be D_tail.1 to D_tail.8.

Now we're going to create the controller bone. This bone belongs to another "chain" of bones responsible for controlling the deformation ones. The controllers don't perform any mesh deformation by themselves. Although in this example this chain has just one bone for the sake of simplicity, more complex rigs can easily have dozens of them.

Still in the armature's Edit Mode, place your cursor just above the tip of the tail and press Shift + A to add another bone. Press Ctrl + R and type 90 so that its orientation is the same as the deformation chain ones. Define this bone's name as Tail. The controller bones are usually named without prefixes in order to be friendlier to the animator, who will look out for Tail instead of C_Tail.

Disable the Deform option on the Bones tab in the Properties window, as seen in the next screenshot, so this bone will not perform any deformations on the mesh:

Now we're going to add constraints to control our deformation chain. Go to the armature's Pose Mode (press Ctrl + Tab). Then, select the bone Tail (which is the controller one), press Shift and then select the bone on the tip of the deformation chain, D_tail.8. Press Ctrl + Shift + C to bring up the Constraints menu and choose Copy Rotation.

This will make the bone on the deformation chain copy the rotations of the controller one, but you will notice that it will copy the absolute rotation (which is not what we want). To make this bone copy the transformation based on its own rotation, select it and go to the Bone Constraints panel, under the Properties window. Check the Offset option and select Local Space on the two drop-down lists, as seen in the next screenshot:

Apply the same constraint to all other bones of the deformation chain: select them and, lastly, the bone which has the constraint we want to copy. Go to the Pose menu on the window header and select Constraints | Copy Constraints to Selected. That will apply the same constraint to all bones of the deformation chain.

Still in Pose Mode, select the Tail bone and rotate it. You'll see that all the bones on the deformation chain follow its rotation like a real tail, as seen in the next screenshot:

Since the animators wouldn't need to see or move the bones on the Deformation chain, you should select and move (the M key) them to another (and invisible) bone layer. I usually move my deformation bones to the last layer, so you can do the same for yours. You should now also turn off the X-Ray option for this armature, since it's no longer needed.

Lastly, select the Tail mesh, hold Shift, click on one bone of the chain, press Ctrl + P, and choose With Automatic Weight to make our armature object actually deform the mesh, as seen in the next screenshot:

Open the file 001-Legs.blend . It has two chains of three bones indicative of two legs of a human, as you can see in the next screenshot. We're going to make shapes for all the bones, and we'll make the bones of each leg a different color:

In Object Mode, create a single plane through Shift + A | Mesh | Circle. On the Operator tab, in the Tool Shelf (press the T key to open it), change the values of Vertices to 8 and Radius to 100.

In the Properties panel (press N), set the name of this object as SHAPE_Leg. Get in Edit Mode (press Tab), select the two vertices positioned over the X axis, and make an edge (F) between them. This would make a line to divide the octagon in half, similar to the one in the next screenshot:

Go back to Object Mode (Tab) , select the armature, and enter into Pose Mode (Ctrl + Tab).

Select Thigh.L and go to the Bone tab in the Properties window. Under the section Display, click on the field called Custom Shape and select SHAPE_Leg. Check the box called Wireframe , which will make your custom shape always be drawn in a more pleasing way, regardless of your current viewport shading. The next screenshot shows these fields:

You'll see that your bone will change from the default octahedron to the shape you just created. But you'll also notice that the rotation and position of the shape don't help much, since we need it at the middle of the bone and perpendicular to its direction. The next screenshot shows the problem:

Select your shape object again, enter in Edit Mode (Tab), select all the vertices (A), and rotate (R) them 90 degrees in the local X axis. You'll see that the bone shapes update automatically. To fix the position, making the shape stand about half of the bone, move (G) the selected vertices in their local Y axes until you are happy with the result. Still in Edit Mode, resize (S) the shape to achieve a reasonable size in your rig. The next screenshot shows the result:

Now you can use the same shape for the Ankle.L bone, using the Display section in the Bone tab under the Properties window.

Repeat the same process and create another shape for the Foot.L bone: be creative and make a bi-dimensional shape of a foot. Name it SHAPE_Foot.L Repeat everything for the other leg and you should end up with something similar to what's in the next screenshot (I've created a simple character mesh to make it easier to see):

Now, the colors! We can use them to distinguish the bones in various ways: a color for the left limbs and other for the right ones, a color for IK and other for FK and so on. The important here is to make it easier for the animator to visually understand the difference between bones. Let's make the left ones red and the right ones green.

Select the left leg bones and press Ctrl + G. Choose Add Selected to Bone Group. This will create a new group of bones called just Group.

Go to the Properties window and select the Object Data tab. Under Bone Groups, you'll see a group called Group. Select it and change its name to Leg_Left on the Name field.

Under the Color Set list, select 01 – Theme Color Set and click on the Assign button to make these bones red. Repeat the task for the bones on the right-hand side leg, choosing an appropriate name and selecting the entry 04 – Theme Color Set to make them blue.

Keep the forearm bone rotated on its X axis for 130^o. Select the mesh and enter Edit Mode (Tab). You'll see that the arm goes back to its original position, as seen in the next screenshot:

We can tell Blender to keep the armature's deformation on the mesh while we edit its vertices, so that it's easier to create the corrective Shape Key.

Go to the Modifiers tab under the Properties window and locate the armature modifier. Next to the eye button, enable the one with the tooltip Use modifier while in edit mode. It will bring us another button next to it. Enable it too. Now we can edit the mesh after the deformation performed by the armature. The following screenshot shows the arm with our desired behavior and the Armature modifier panel with the highlighted options:

Go back to Object Mode (Tab), go to the Object Data panel under the Properties window, and find the section called Shape Keys. Click twice on the plus sign to create two Shape Keys: one called Basis, which is the base state of our mesh, and other called Key 1, which is the one we will work on.

Change the last Shape Key name to Arm_Left. This is important when dealing with complete characters and lots of Shape Keys.

We're going to use both the sculpting tool and the Edit Mode to build our corrective shape. In order to be able to work on a Shape Key in Sculpt Mode, we have to pin this shape.

With the Arm_Left key selected, click on the pin icon, just below the Shape Keys list. You should disable it when you're done sculpting. The next screenshot shows the Shape Keys section and the pin button highlighted:

Sculpting in Blender is pretty straightforward: select the mesh, pick Sculpt Mode in the 3D view mode list on the window header, and start sculpting the mesh. Under the Tool Shelf (T) you can select the appropriate mode of sculpting, such as Inflate, Grab, or Smooth, for instance. Use the Inflate tool for growing the biceps, such as in the following screenshot:

Since not everything will look right just with sculpting, disable the Pin button for the Shape Key you've enabled at step 5, enter into Edit Mode, and tweak the vertices until you're happy with the result of the arm bending shape. Go back to Object Mode when you're done.

Now comes the magic part: now that you have two shapes for your arm, we need to set a driver, so the rotation of the forearm bone on its X local axis triggers the morphing between those keys.

Below the Shape Key's name in the Object Data tab is a slider called Value. Right-click on it and select Add Driver. This will turn the slider into a pink color, which is how Blender shows you that this channel is driven by another object, expression, or property. The next screenshot demonstrates that:

Open a Graph Editor window to set up the forearm bone as the driver for this shape. Select Drivers from the Modes list in the header.

On the left panel, click in Value (Arm_Left) in order to see the pink line in the editor. On the Properties (N) panel, leave the driver type as Scripted Expression and change the Expr value to var.

In the box just below the Add Variable Button, leave Transform Channel on the first item; select Armature from the Ob/Bone selector and also the bone forearm in the box that will appear after choosing the armature; select X Rotation in the last list and check the Local Space box. This will tell Blender to take into account the local X rotation of the forearm bone to control the blending between the Basis and Arm_Left shape keys.

Rotate the forearm bone on its X axis to see the transformation. The biceps and skin get changed when you rotate the forearm, but the transformation happens earlier than we would expect.

To fix that, look for the Generator box inside the Modifiers section on the Properties panel. Change the Y value to -1 so that the blending between the Shape Keys starts only when the arm bending is closer to its final position. The next screenshot shows the driver and its values set:

Select the bone D_arm and go to its Bone Constraints tab under the Properties window. Under the first constraint, named IK_arm, right-click on the Influence slider and select Add Driver as seen in the next screenshot. You'll see that the Graph Editor window above the 3D View gets updated and the Influence slider turns into a pink color:

Under the Graph Editor, click on the driver on the left-hand side panel. Its properties will be shown on the Properties Panel (N). Navigate to the Drivers session, leave it as Scripted Expression, and change the Expr field to var.

Below the Add Variable button, leave the first list value as Transform Channel, select the Armature object on the Ob/Bone field and the bone called IK_FK_switcher.

Since we need this switcher bone to act as a horizontal slider, keep the X Location value and just enable Local Space. The next image shows our driver set:

Go back to the Bone Constraints tab under the Properties window. Now, instead of creating the driver from scratch, let's use one of the new useful features in Blender 2.5: right-click on the pink Influence slider on the IK_arm constraint and select Copy Driver. Next, right-click on the Influence slider from the FK_arm constraint and select Paste Driver. Now, both constraints will have the same driver.

Since we need this FK driver to act contrary to the IK, head over the Graph Editor and click on the FK driver (named Influence (D_arm: FK_arm)). On the Properties Panel (N) at the right, you'll see that all values were copied from the first driver. Since we need an inverted mapping, just change the Expr field value to 1-var. That's all we need to do create the inverted driver. The next screenshot shows the driver setup values:

Now you should use the drivers set for the D_arm bone constraints as reference to the remaining bones on the deformation chain. You can use the process described in step 5 to copy the driver from the IK_arm constraint and paste it to the IK_forearm and IK_hand constraints. Do the same to the FK constraints and you're done. No need to change anything in the drivers values.

When you finish setting up the remaining drivers, move the FK and IK bones to different locations and switch the IK-FK slider: you'll see that the deformation bones (and the arm) alter between chains as you move the slider. The next screenshot shows the switcher in an intermediate position, where the deformation bones (and the arm) act under the influences of both IK (blue, medium width) and FK (red, fatter) chains.

Select the mesh, hold Shift, select the armature (or one of its bones, in the case the armature is in Pose Mode) and press Ctrl + P. Select Armature Deform With Automatic Weights. This will tell Blender to guess the influence of each bone on the mesh based on its size and position, painting the basic weights. This process is also often called Bone Heat , and (if you have created a good bone structure, matching the proportions of the mesh) brings us very reasonable results.

Enter in the armature's Pose Mode and try to move and rotate some bones. Notice that besides the automatic weights having being assigned quite reasonably, you may find some cases where the deformations need some adjustments.

Select the mesh again and enter in Weight Paint Mode (Ctrl + Tab). You'll see that the mesh color turns into a deep blue, and the last bone you selected in Pose Mode becomes selected again. The region affected by this bone gets colors in a gradient that goes from zero influence (blue) until 100% influence (red). The next screenshot shows different weight colors on the mesh after selecting the arm bone in Weight Paint Mode:

While in Weight Paint mode, you can still move the bones as you wish to test the influences you set in real time. Every time you select a bone, the mesh is updated to show the equivalent influence.

Make sure your Toolbox (T) is activated and select one of the painting tools available to adjust the weights on the Tools section. They act much like in 2D applications such as Gimp or Photoshop, allowing you to Add, Subtract, Blur, Darken, or Lighten weight colors. The Blur option, for example, is very useful to get smoother transitions on the weight colors.

If you use a graphics tablet, you can enable the pressure sensitivity on the Brush Tools section by clicking on the pointing hand besides the brush values. If you enable it, the sensitivity would pass values that go from zero to the value set on the slider. You can enable the sensitivity per value, so you can use a fixed value for size and a pressure driver for the brush strength, for example. The next screenshot indicates the options:

To paint weight values on both sides of a character at the same time, enable the X Mirror option on the Toolshelf (T). You can paint the influences for the left limbs of your character, and the same weights will be applied for the right ones. This will work only when your bones have suffixes such as .L or .R to a proper identification.

When painting weights on the torso or head, for example, it is not possible to assign mirrored weights by using only X Mirror because there are no mirrored bones to take information from. This is when you should use the Topology Mirror option: it uses the information from the underlying edge loops on the mesh to apply mirrored weights based on the X axis.

To avoid painting on unwanted parts of the mesh, you can enable the Face Selection mode to select only the parts of the mesh that you want to paint over. Click on the Face Selection icon on the window header and select your desired faces as you would do in Edit Mode. The B and C selection keyboard shortcuts work as expected. The next screenshot shows the mesh with the Face Selection mode activated and an indication to the relevant icon on the window header: