Essential Blender- P13 pdf

Figure RSD.15: An Armature Modifier. Select the mesh, and in the Modifier panel add a new Armature modifier. Type in the name of the armature that you want to link to your mesh. Do not hit the Apply button. In the modifiers panel, the Apply button removes the modifier and causes any modifications it had made to the mesh to be permanent. Once the Armature modifier is added to the mesh and properly targeted at the armature itself, there are two options for how it will deform the mesh: Envelopes and Vertex Groups. You can use either one or both. Envelopes use visual areas of effect to determine which portions of the mesh are moved by which bones. Vertex groups allow you fine control, down to the mesh vertex level, over what affects what. Envelopes Image:Dummy.png Figure RSD.16: The head bone's Envelope, and the Armature Bones panel. Many people find envelopes an intuitive way to work. To see the envelope of a bone, enable the Envelopes draw type in the Armature panel under the edit buttons. The envelope of a bone is shown by the white ellipse surrounding it. Any area of the mesh that falls within that envelope will be deformed when the bone is moved. The goal when using envelopes is to tweak the size of the envelopes so that they enclose just the area of the mesh that you want to deform with a particular bone, but no more. Adjustments to envelopes can be made in both Pose mode and Edit mode. Use either Alt-S or the "Dist:" field in the Armature Bones panel to adjust the spread of the envelope away from the bone. RMB selecting a bone in Pose Mode and pressing Alt-S lets you interactively scale the envelope size without changing the size of the bone itself. Likewise, using the S-key in Edit mode while envelopes are displayed scales only the envelopes, not the bones. When in Edit mode, you can scale the envelope for the entire bone, or scale the roots and tips individually, depending on what you have selected. Image:Dummy.png Figure RSD.17: Hank's armature with the envelopes adjusted to cover the mesh. Since the effect of a bone envelope is determined by these adjustments, you don't have vertex- by-vertex control. If you can get away with using envelopes for your armature, great! However, as envelopes are both less precise and somewhat slower than the other skinning method, for anything of middling complexity, it's necessary to assist envelope deformation with vertex groups. Vertex G roups A vertex group is a list of some of the vertices of a mesh. A mesh vertex can appear in as many different vertex groups' lists as you care to place it in, or it could belong to none at all. When using an Armature modifier that has the Vertex Groups button enabled, you can tell a bone to move part of the mesh by selecting vertices in the mesh and assigning them to a vertex group with the exact same name as the bone. For even more control, the vertices that are assigned to a group are given a weight. The weight, a value from 0.0 to 1.0, determines how strongly any actions performed on the vertex group will affect that particular vertex. For example, if one vertex appears in two different vertex groups (which happens a lot!) those vertex groups may be pulling their vertices in two different directions. Which group does the vertex follow? Well, if the vertex's weight in each group is 0.5, the groups have equal influence over the vertex, and it ends up splitting the difference. If, however, the vertex has a weight of 0.1 for the first group and 0.9 for the second group, the second group will have more influence, and the vertex will follow the second group's deformation much more closely. Vertex weights are always relative to the weights from competing groups. One vertex can belong to many vertex groups, and one vertex group can have many vertices, each with a different weight. Assigning these weights is often necessary for organic models, where joints are supposed to deform smoothly. Around a shoulder joint, for example, the weights might have to be adjusted so that the upper arm doesn't pinch too much when the arm is lowered. Manual Ve rtex Group Assignment Figure: Vertex Group panel There are several ways to add vertices to a vertex group. The "manual" way gives you by far the most control. In Edit mode on your mesh, select several vertices. Under the Link and Materials panel in the Edit buttons, there is a Vertex Groups section. Click the "New" button to create a new, empty vertex group. Image:Dummy.png Figure RSD.18: The Vertex Groups controls in the Link and Materials panel of the Edit buttons. Then click the Assign button to assign the selected vertices to the just-created vertex group. When you click assign, the selected vertices are added to the vertex group's list, using the weight that is indicated in the Weight field. Note: If you have changed the Weight control for any reason, either manually or through weight painting, and you click Assign, your vertices will use whatever weight is there, even if it is 0.0. It's a good idea to make sure that it is set to 1.0 before you create and assign a new vertex group. If a vertex group is not acting as you think it should, assigning vertices with the Weight control set to something other than 1.0 could be the culprit. Different vertex groups can be selected by choosing them from the dropdown box in the Link and Materials panel. Here are some of the controls for working with vertex groups: - Delete: destroys the vertex group. This will not delete the vertices from the mesh itself - remember, vertex groups are just a list of vertices. This button destroys the list. - Assign: adds the vertices that are currently selected in the 3D view to the active vertex group - Remove: removes the vertices that are currently selected in the 3D view from the active vertex group. If the vertices were not in the group already, this has no effect. - Select: selects any vertices in the 3D view that are assigned to the active vertex group. This adds to the current selection in the 3D view; it does not replace it. - Desel.: deselects any vertices that are selected in the 3D view and that are assigned to the active vertex group. Assigning Vertex Groups with Weight Painting Manually adding vertices to vertex groups quickly becomes tedious. Sometimes you need that kind of vertex-level control, but for more common use, you can graphically assign vertex groups and weights to vertices. This is done in Weight Paint Mode, which can be chosen on the 3D view header. Image:Dummy.png Figure RSD.19: Choosing Weight Paint mode. You should make sure that the armature is in Pose mode and that it is set to X-Ray so it will be visible through the mesh while you work. Upon entering Weight Paint mode on the mesh, it will change color (all dark blue if you haven't added any vertex groups yet) and the cursor will turn into a paintbrush. Image:Dummy.png Figure RSD.20: Hank ready for weight painting. How to A pproach Weight Painting Select the mesh and enter Weight Paint mode. Select a bone - even though the mesh is active, if the armature is in Pose mode you will be able to RMB select individual bones - and press the W-key. This brings up a confirmation for "Apply Bone Envelopes to VertexGroups." LMB click to confirm this and you will see the mesh change color. In terms of vertex group weights, blue means 0.0, red means 1.0, and the rest of the spectrum falls in between. This W- key option auto-paints the mesh with the influence of the selected bone's envelope, which is a good place to begin tweaking. In fact, if you plan to use vertex groups for your deformation, here's how to proceed: Turn off Envelopes in the mesh's modifiers panel and turn on Vertex Groups. Select the armature, enter Pose mode, and use the A-key to select all of the bones. RMB click the character mesh and enter Weight Paint mode. Before directly selecting any bones, press the W-key and confirm that you want to "Apply Bone Envelopes to VertexGroups." Even though you can't see it, you've just had Blender create beginning weight paintings for every bone in the armature. Now, selecting individual bones will show you their weights on the mesh. Image:Dummy.png Figure RSD.21: The Paint panel for weight painting. The actual weight painting works by simply LMB dragging on the mesh model in the 3D view. The Weight control on the paint panel sets the maximum weight that the brush will paint. Opacity indicates how much of that Weight will be painted with each pass of the brush. Of course, the Size control indicates the size of the paint brush itself. Some people find it useful to enable the "Wire" option at the bottom of the panel, which superimposes the mesh's wireframe structure over the painted colors. If you find that you've made a mess of a particular vertex group's paint job, just press the "Clear" button to remove any weight painting for the selected bone. If you are working with a symmetrical mesh and armature, and the bones are named properly as described before, you can enable the X-Mirror option. X-Mirror allows you to weight paint only one side of a character, and have your painting mirrored to the other, saving you the trouble of duplicating your work on symmetrical characters. Clearing weights with the Clear button does not work symmetrically, regardless of the set up. With a bone selected, you can use the normal posing tools (rotation, translation) to transform it, letting you see how well your weight painting is working. In fact, you can set a pose on any or all bones, then continue to tweak your weight painting from there. The deformation will update in real time, giving you immediate feedback as to the quality of your work. If you have rotated an arm downward and see that the rib area is deforming too, you can set Weight to 0.0 in the Paint panel, Opacity to around 0.25 and start painting in the areas that deform too much. In this way, you can continue to weight paint, select and move bones to test, and tweak some more until the mesh deforms smoothly over the range of motion your armature will experience. Conclusion Armature creation, rigging and skinning are complex topics, and this is the merest overview of the relevant tools available to the Blender artist. Techniques for creating advanced rigs are constantly evolving, and can only be understood once you have a strong grasp of the basics. Included on the disk with this book are several rigs of varying complexity that have been released for general use. Some of them might function beautifully but be almost incomprehensible from a beginner's standpoint. Fortunately, the artists who created them have explanations and instructions for their rigs which have also been included on the disk. Perhaps the best way to learn some of these advanced techniques, besides sitting down with the artists themselves, is to study these rigs: pick them apart and see how they function. Of course, you shouldn't feel that you have to create a rig from scratch every time you approach a new piece of animation. Many artists are quite content to use already-created rigs, and there is no shame in it. If you try the tools, though, and find that rigging interests you, you might be the person who creates the next great rig that everyone else is using! ! Chapte r 7: Rigging and Skinning: Hands On By Roland Hess The best way to animate a complex mesh object like a character is through the use of Armatures. An armature acts like a skeleton: you actually move the bones of the armature and those bones drive the animation of the character mesh. The process of building an armature is called "rigging," and the process of attaching the armature to a mesh is called "skinning." Many artists are intimidated by the complicated controls and advanced functionality of the freely available Blender rigs and are put off from rigging altogether due to its perceived complexity. The armatures are excellent, and their creators have put great amounts of time and effort into making them flexible and efficient. It is possible, however, to create a fairly useful rig without creating dozens of hidden control bones. That is what you're about to do. Getting Started Open the file "hank_for_rigging.blend" from the "examples" folder on the included disk. Figure RST.01: The screen when you open "hank_for_rigging.blend". This is the Hank mesh that you will be familiar with if you have already worked through Chapter 6. The first thing to notice before you even begin building an armature is that Hank has a rotation and a scale. Figure RST.02 It's always a good idea to begin working with character animation and armatures in a completely clean transformational state. With Hank selected, press Ctrl-A to apply the transformations, leaving Hank looking exactly as he does but removing the transformations. Figure RST.03: The Properties panel for Hank after applying transformations. Tip: Before working with armatures, use Ctrl-A to Apply all transformations to your mesh. Now that Hank is ready, create the armature. Use the spacebar toolbox to Add->Armature. That new object sticking up from the ground at Hank's feet is a bone. Just like adding mesh objects to the 3D view, the armature and bone begin their existence in Edit mode, which will allow you to add and destroy bones, create parent/child relationships between them, and adjust their positioning to fit inside Hank's body. During this stage of armature creation, the Transform Manipulator isn't very useful, so turn it off by using Ctrl-Space->Disable or by clicking the pointing finger disable button on the 3D header. Figure RST.04: The new armature, with a single bone. With the manipulator gone, it's easy to see that the top ball of the bone (called the "tip") is yellow, while the bottom ball (called the "root") is purple. Yellow, as elsewhere in Blender, indicates that the tip is selected. You can see this by pressing the G-key to enter Grab mode and watching the tip move around as you move the mouse. Notice that as you move the tip away from the root, the entire bone grows along with it. When you're done moving it, press the RMB or Esc-key to cancel the transformation, putting you back to where you were when the bone was first created. If you accidentally accepted the transformation with the LMB, remember that you can always Ctrl-Z to undo. One other thing to notice is that neither R-key rotation nor S-key scaling seem to have any effect on this single bone node. This bone will be the master bone for the entire armature, meaning that all other bones you add will be connected to it either directly or indirectly, so that when the master bone is transformed, the entire armature will follow it. You could leave it pointing up like this, but most people find that this sort of master bone is better visualized horizontally. Switch to a side view, and, using the G-key, move the tip of the bone back and downward until it lines up horizontally with the root of the bone. Holding down the Ctrl-key while doing the transformation will help you to get it right on. The length doesn't really matter, but you should make it stick far enough out behind Hank that it will be easy to select even during a cluttered animation session. Figure RST.05: The tip of the master bone moved back and down.