Blender 3D: Noob to Pro/Advanced Tutorials/Advanced Animation/Guided tour/Armature/edit
|Applicable Blender version: 2.4x.|
Now you've got your armature, but it's not much use until you add some more bones to it. Think about your body for a moment -- you've got this thing you call a 'skeleton', which for our purposes corresponds more or less to an armature object. Your skeleton consists of a number of bones (about 206, to be precise), but generally these are not independent from each other. If you move your femur (the bit of your leg between your pelvis and your knee) then conveniently the rest of your leg moves with it. In that example, the tibia/fibula would probably be counted as one bone, with the femur as their 'parent' bone. In this way, you build up a hierarchy of bones, making animation much simpler.
Editing an Armature Object gives you the chance to add, move or connect bones together. Whilst in edit mode, you will see all of the bones within the currently selected Armature.
When you create a new armature in Object mode a single bone will automatically be created for you, centered at the cursor position. Blender will then switch straight to Edit mode to allow you to add further bones. At this point we're just defining the default 'rest' position of the bones and specifying how they connect together -- you'll have to wait until the next chapter to find out how to create specific poses.
Now the basics about bones
Having created and selected an armature in Object mode, you can add and modify the bones in this armature by switching to Edit mode.
- You can add a new bone at cursor position by pressing SPACEKEY in the 3DView --> Add --> Armature.
- A bone has two ends: a root (the lower part) and a tip (the upper part). You can select and move the tip or the root independently with RMB, or you can select the entire bone by clicking on its body.
- You can extrude a new bone from the selection using EKEY. This will create a bone connected to the original one, meaning the Root of the new bone will follow the Tip of the original one. You can also CTRL-LMB to extrude a new bone. It will extrude to where you clicked.
- Alternatively, you can connect two existing bones by selecting them one after the other and pressing CTRL-PKEY. You can then choose either 'Connected' (the child bone - the one you selected first - will automatically be moved so that it touches the parent) or 'Keep offset'.
- You can use SHIFT-DKEY to duplicate a bone
- Using the WKEY menu, You can subdivide your bone or flip the name of the bone between Left-Right (See Naming convention below).
- You can delete the bone with XKEY
- You can select a chain of bones (connected together) using LKEY, when you hover your mouse over a bone.
The edit panel
- Armature Bones Panel
- OB: this field lets you rename your bone.
- "Child of" Dropdown: lets you choose which bone will be the parent of this bone. If a parent is selected, there will be a small button labelled "con", meaning connected. Setting the parent defines the relationship between your bones. When one bone has another as its parent, it will do everything the parent does, such as rotate, move and scale. A dotted line between the parent and child will appear. If you select Connected, the Root of the Children will go stick to the tip of the parent, giving you a chain of bones like the 2 bones in your arm.
- Segm: If you set this value to something greater than 1, it will cut your bone into several little segments and deform them on a bezier curve - referred to as a 'B-Bone'. You need to create a chain of bones to really show off this feature though. In the example below, the image on the right has 1 segment, and the one on the left has 3 segments each (these are shown in Object mode to show the effect more clearly):
- Dist: This is the area of influence of the bone. It can be visualised using the Envelope display mode. We generally don't touch this field as there is an easier and faster way to change this option. Turn Envelope on and select a bone. Then using ALT-S, you can scale the zone of influence. This has the advantage that you can do it on multiple bones simultaneously, and it works in both editmode and posemode:
- Weight: This specifies how strongly this bone will influence the geometry around it, relative to the other bones. If two bones crossing each other, both with envelope influence, have the same weight (like 1:1) they will influence the surrounding geometry equally. But if you set one to 0.5, the geometry will be affected more significantly by the other one, with weight 1. For example, in this image, 2 bones using envelope influence try to move the same geometry. The 2 on the left have the same weight, you can see the geometry didn't move. On the right, one of the bones has 0.5 so the bone with weight 1 is winning the tug-of-war!:
- Hinge: This tells the bone to remain motionless in a chain. It doesn't copy the rotation and scale of the parent. Useful for mechanical rig I would say, as you can animate the rotation of the hinge bone without having to correct it because the parent rotated:
- Deform: This lets you say if you want the bone to deform the geometry at all. Switching it off is like setting the weight to 0, except it's faster this way. Useful when using a bone as a target or a controller, i.e. a bone you just want to use to control other bones, but not the geometry itself.
- Mult: to deform geometry you can use vertex group and/or Envelope. The ability to mix both of these methods is handy for using one to tweak the other. For example, you might use envelope everywhere but tweak difficult places manually with vertex group. We'll discuss this in more detail later on.
- Hide: This option lets you hide the bone. You can use it to hide the less important bones when you want to see what you're doing or for when you come to animate later on. For example, when you animate you don't need to see the entire chain of the leg, just the controllers. The values you select here apply to both Editmode and Posemode.
In many cases, rigs are symmetrical and can be mirrored in half. In these cases, it is helpful to use a left-right naming convention. This is not only useful for your own sake, but it gives Blender a hint that there is a pair of equivalent bones, and enables the use of some very cool tools that will save you some significant work.
- It's helpful to name your bones with something useful telling you what it's there for, such as leg, arm, finger, back, foot, etc.
- If you get a bone that has a copy on the other side, however, like the arm (you have 2 arms right?), then the convention is to call them arm.Left and arm.Right.
- Other alternatives are also possible, like _L, _LEFT, _left, .L, and .Left. Anyway, when you rig try to keep this left-right thing as accurate as possible; it will pay off later on.
- You can copy a bone named blah.L and flip it over using WKEY --> flip name. So the bone will be blah.L.001 after you copy it, and flipping the name will give you blah.R. Blender handily detects if the .001 version already exists, and increments the number for you.
This is an example of naming in a simple rig:
Now we come to the X-Axis Mirror Edit feature. This handy little number allows you to define only half of your character and tell Blender to automatically repeat the same actions on the other side. It's cool, it's simple and it saves a whole lot of time.
We will create a little guy out of sticks for the occasion -- don't worry about the geometry yet.
- Create a new, empty scene. Since the mirror editing feature mirrors along the X Axis, make sure you've got the front view selected (NUMPAD_1KEY) so that the X Axis runs from left to right. Add a new armature to the scene (SPACE, Add|Armature). Enable 'Draw names' from the 'Display options' section of the Editbutton panel, so we can see what we're doing.
- Now enable mirror editing by pressing F9 on the buttons window and clicking the X-Axis Mirror button in the Armature panel under Editing options. You'll also need to use the center of the armature (indicated by a purple dot) as the center of your rig, otherwise the symmetry will go wrong when we come to create the mirror image.
- Name the first bone you have "Back". You can scale it to make the entire back of the guy.
- Select the tip of this and extrude a new bone from it to do the Head. Name it Head.
- Select the tip of Back again and do SHIFT-EKEY to tell Blender you're starting a mirrored chain of bones. Blender will automatically extrude another bone and will create an exact mirror of whatever you do. Take note that the name of both bones are Back_L and Back_R. Blender also tries to keep to the naming convention. Unfortunately, since we extruded from the Back bone, the names aren't quite right anymore.
- To change the names: Start by editing one of the names as Arm. Add the suffix to it (_L or _R). Then hover your mouse over the name field and do CTRL-CKEY. You just copied the name of the bone! Select the other bone, hover you mouse over the name field and do CTRL-VKEY. This will paste the name as-is. But as there is already a bone with the same name, Blender will add .001 after it. No problem; just go into 3Dview and do WKEY --> Flip name. There you have it -- a working mirror again.
- Mirror editing works using names. If you move a bone named blah_L and there is a bone named blah_R in the same armature, Blender will mirror the move you do to it, so make sure you follow name convention correctly.
- Then we can continue: extrude an other bone to make the lower part of the arm using EKEY or CTRL-LMB. The new set of bones should be arm_L.001 arm_R.001.
- Then we will add the legs. Up till now we have always worked from the tips of the bone. This is easy as Blender understands you want to create children of the selected bone, but to make the legs you need to extrude from the root of "Back". So go ahead, select the root of "Back" and do SHIFT-EKEY to start a pair of chains. Rename them to "leg"+suffix.
- Now take note that doing so will not parent or connect the new bones to anything. We don't want it to be connected to the tip of "Back", it would look silly. But we want it to follow the body!
- The way to go is to parent the two legs we just created to the "Back" bone. The old way (pre 2.40) was to select all bone and select the parent manually in the drop down. In the new version, editmode and posemode have an active bone. The active bone is the last bone you selected. In this case we can't work with more than 2 bones selected. Select the child (a leg) then select the parent (Back) and Do CTRL-PKEY. A menu will popup asking Connected or Keep offset. For now use Keep offset. Do this for the other leg as well.
- it's also possible to remove parent easily. Select any bone you want to remove parent relation from and do ALT-PKEY. A menu will popup asking if you want to clear all or just to unconnect. Of course you don't need to select the parent and/or the child for this to work since any parent relationship will be cleared. So if you do that on a bone which is parent of 5 bones, then immediately all the children will be parentless.
- Extrude one more time to get a leg with 2 bones.
- Turn on the Stick display mode and enjoy your guy made of sticks!
- Now you can go into Posemode and pose your guy as you want.
- You can move the entire guy just by moving the "Back" bone, since this is how we built him. This bone is the highest in the bone hierarchy, "The daddy of all bones", you could say!
FASTER WAY TO NAME YOUR BONES 1) Create one side of the armature complete with correct bone names like the way this tutorial describes. 2) Copy the side of the armature you just created and paste it on the opposite side to form a complete armature. 3) On the side that you just duplicated, your names would have numbers added to them. Now select each bone on 3D View and hit "W" then select "FLIP NAME". MAKE SURE YOUR PARENTING IS THE SAME AS THIS TUTORIAL DESCRIBES!