Essential Blender- P15 docx

Adding Bones to Assist Deformation Figure RST.63: The head bone in Edit mode, showing envelopes. With this armature, there is no way to have the head bone's envelope be broad enough to deform the entire head without dipping into areas like the shoulder and chest that have no business being affected by the head bone. What to do? There are several ways to approach it, but the easiest is to add a new bone as a child of the head bone to assist with the deformation. Figure RST.64: A new bone to help with head deformation. Notice how the envelopes of the original and new head bones completely cover the head now. To get this configuration, we Shift-D duplicated the head bone, then positioned the new bone's root and tip so it fell perpendicular to the original. After that, the overall envelope size was altered with Alt-S until it appeared to fill in the gaps the original bone had left. Of course, this new bone must be made the offset child of the original head bone or things will go very badly once you begin to animate. Then, we returned to pose mode and tested it by moving the neck and head. In fact, our first attempt when creating this exercise didn't quite cover the area correctly, and an additional adjustment had to be made to the envelope size. Weight Painting and Ve rtex G roups The last way of adjusting mesh deformation that we'll talk about is called Weight Painting. Behind the scenes, it involves the creation and use of vertex groups, but the 3D view interface elements let you work rather intuitively. Figure RST.65: A bad deformation in the chest. In this illustration, Hank's back has been bent backward, showing off a poor deformation in the chest. You could add another bone that was linked to the spine to fix it, but there is another way. To weight paint your way out of a mess like this, select the mesh object, and on the 3D header choose "Weight Paint" mode. On the mesh's Modifiers panel, enable the "Vert. Groups" button in the Armature modifier. Figure RST.66 Figure RST.67 Although the mesh object is selected, you'll find that you can RMB select the bones of the armature, if it was in Pose mode. In this example, the "spine.top" bone has been selected. At this point, the LMB in the 3D view becomes a paint brush. What the brush is "painting" is really bone influence. As you click and drag on the mesh, it is telling the mesh that it should be influenced by the currently selected bone. In terms of color, dark blue means that the mesh is not influenced by the bone at all, through teal, green, yellow, orange and red, at which point the mesh is influenced by the bone's transformations at 100% strength. Figure RST.68: The weight paint panel on the Edit buttons. You can choose to what maximum weight you would like to paint in this panel with the "Weight" control, and how much of that maximum value will be painted with each stroke with the "Opacity" control. An opacity of 1.0 will paint the full value of the Weight control with every pass of the mouse. Figure RST.69: A few mouse clicks on the chest and sternum later. By painting a few strokes on the poorly deforming area with Weight 1.0 and Opacity .25, this deformation was achieved. A definite improvement. Serious animators will use this technique to finely tune their deformations for nearly each and every bone in their characters. W rapping Up When you have envelopes and weight painting set so that each controller can move, deforming the portions of the mesh you desire while leaving other parts alone, then you are done. Move any deformation helper bones you created to a hidden bone layer so they are out of the way. If you need to revisit your envelope settings or weight painting, though, don't forget they're there! If you have already worked with Chapter 6, we encourage you to try it again with the rig you just created. It's different than the rig provided with Hank in the previous chapter, and you can learn from the differences in how your rig responds to the same set of instructions. Chapter 8: Shape Keys: Tools By Andy Dolphin You already know that in Blender you can animate the way that objects move around the 3D world. Blender also gives you the ability to have your mesh objects change their shape over time. These changes, called deformations, are saved in "shape keys". Examples of where you might use shape keys include morphing from one character or shape to another, or adding subtle variations to a shape to add interest to an animation, like having a creature's chest rise and fall to show breathing. One very popular use of shape keys (sometimes called "morph targets") is for character facial expressions and lip-syncing. Shape keys are not restricted to animation however. If you have a model you wish to use in a series of still images, shape keys can be a convenient way of saving shape variations that will be used more than once. Figure 8.2.1: Various facial expressions created only with shape keys. Shape keys store vertex positions relative to their original positions in the mesh. After the shape key is stored, the deformation can be controlled by influence sliders. Moving the sliders causes the vertices to change from their positions in the original mesh shape and move toward the positions saved in the selected shape key. Multiple shape keys can also be combined to vary the final shape of the mesh. The original shape of the mesh is saved as a basis shape key. It is always available and can be returned to at any stage, no matter how many shape keys have been made from it. As shape keys are non- destructive, you can try out various ideas on changing or improving a model, and if you find you don't like them, you can delete or ignore them, returning to the basis shape. Keep in mind that shape keys do not allow you to change the structure of the mesh, only the positions of the vertices which make up the mesh. You cannot add or delete vertices when using shape keys. Making Shape Keys Before you begin Before working on your shape keys, be sure that you are happy that your basic model is finished. One important point to remember when working with shape keys is that since they store relative vertex positions, the mesh should be in a finished state before applying them. While some editing is possible after shape keys have been saved, it can lead to unpredictable results and may make some of the shape keys useless, in which case you'll need to recreate those shape keys from scratch. It is common practice to build organic models, like humans and animals, using a mirror modifier so only one half has to be modeled while Blender automatically creates the other half. If you've used a mirror modifier while modeling, make sure to "Apply" it (join the two halves) before proceeding with shape keys, as applying mirror modifiers later will result in the loss of all shape keys. Shape key controls are found in the Shapes tab of the Editing Buttons (F9). Shape keys are added to a mesh in Object mode. Then, the shapes are made and edited in Edit mode. Figure 8.2.2: The Shapes tab before any shape keys are saved. If no shape keys have previously been stored for a selected mesh object, the Shapes panel will show a single button with the label "Add Shape Key." When this button is pressed, the panel changes to show a button labeled "Relative," which is active by default, and a drop-down menu with the word "Basis" showing in the text field. This shows you that Blender has stored the current state of the mesh as the Basis shape key. The Basis shape key is essentially the original un-deformed mesh, and all future shape keys for this mesh will be stored relative to this shape key. Figure 8.2.3: The Shapes tab with basis shape key saved. Pressing the "Add Shape Key" Button again results in a new shape key labeled "Key 1" being added to the drop-down menu. The key name can, and usually should, be changed to something that will indicate what this shape key represents. For example, when making mouth shapes for lip-sync, the shape keys should be given names that indicate the sound or letter each key represents. If you fail to do this, a lot of time will be wasted when you go to actually use the shapes in an animation. You can edit the name of each shape key by selecting it from the shapes panel menu, then typing a new name into the text field. Figure 8.2.4: The Shapes tab after the first shape key is saved. When the first new shape key is added, you will see a key value slider, a "Min" and "Max" adjuster and a text box labeled "VGroup:" in the Shapes panel. These give you additional control over the shape key, which will be explained in a bit. A list of shape keys with sliders also appears in the Action Editor window (Action window), if one is open. When animating with shape keys, it is usually better to do so in the Action Editor as multiple shape keys can be easily accessed without scrolling through a menu, and markers are placed to indicate key frames for each shape key. Figure 8.2.5: The Action Editor window showing a list of shape keys. Once a shape key has been created, a unique target shape can be made by tabbing into Edit mode. Selected vertices, edges or faces can be moved, scaled or rotated to create a new shape. Remember that vertices, edges and faces should not be added or deleted when making shape keys. After the mesh has been modified into the desired shape, it can be stored by exiting Edit mode. Each time the "Add Shape Key" button is pressed, a new shape key is created, ready to store a new shape. Shape keys can be selected from the drop down menu next to the shape key names or by scrolling through all keys using the "Previous Shape Key" and "Next Shape Key" buttons. Using One Shape Key as the Basis For a New One New shape keys are based on the currently selected shape key at the time the "Add Shape Key" button is pressed. So, if the Basis key is selected, the new shape key will be a copy of the Basis key, ready for editing. Sometimes it is useful to have two or more keys that are similar to each other. In this case, an existing shape key should be selected before pressing "Add Shape Key". Then, when entering Edit mode, the mesh will already be deformed to the same state as the previous shape key. From here, minor or major adjustments can be made to the mesh to create the new shape key. This can save quite a lot of time when creating similar shape keys in complex models, as the majority of the adjustments would only need to be done once. Subsequent shapes could be based on the first adjustment. . Blender has stored the current state of the mesh as the Basis shape key. The Basis shape key is essentially the original un-deformed mesh, and all future shape keys for this mesh will be stored