5 Steps to Rigging a Mace With an Emphasis on Overlapping Action
When it comes to learning overlapping action, you need a rig to be able to practice on. Many times you'll find a tail, or a type of pendulum to be able to animate with. In our Character Animation Fundamental series where we teach you the basics of animation, with the latest article being Overlapping Action we used a very simple Mace. In this article, you'll learn how to properly set up the rig used in that article.
If you want to learn the basics of rigging, this series is a great stepping stone for you. If you're an animator, then knowing some of these basics being taught in this series can be a huge help for you. While knowing how to rig as an animator is not essential, it's still an excellent skill to have, because you never know if you'll need to create some simple rigs at your job, and at the very least you'll know how to properly communicate with the rigging artists within the pipeline.
We already have the mace modeled out, and you can download the scene file here: Mace_Model The mace is definitely nothing special; the key here is to have a rig that can help teach the principle of overlapping action, and what better way to do that than with a weapon made up of mostly chain links?
Step 1: Creating the Control Curves
The first step is to create the control curves for the rig. You can really make them anyway you like. For this, however, we kept it very simple and dropped in a simple NURBS circle. Scale it large enough so it's very easy to see and select. Position it in the center of the very top chain link.
In order to create this rig there will be no bones or joints involved, instead, we are going to just use some clever parenting to get this mace to behave how we want. In a nut shell, creating various constraints is the very basics of rigging and should be the first thing to tackle when learning how to rig.
The next step is to copy the control curve you created down the chain. So you'll place a curve at each chain link. Once you get down to the actual ball of the mace you can place it in the middle and scale it out accordingly to ensure that it's visible and easily selectable.
For the handle of the mace, let's create a different control curve to distinguish it from the chain links. So first create a cube, and scale it out into more of a rectangle shape. Now select the CV Curve tool, and hold down "V" and snap a point on each vertex of the cube. You can go ahead and delete the cube, and you should have a square control curve. Now move it toward the middle of the handle and scale it so it's easy to select, but doesn't get in the way of the other control curves.
Step 2: Freeze Transformations
The next step is pretty simple, but it's extremely important, especially when rigging. Freezing the transformations sets all the values back at zero. So right now there are various translations and scales on the control curves. If you didn't freeze the transformations, those values would be the default values. So if you animated the control curve, and wanted to get it back to its original position, you would have to remember the values in the channel box. Setting the default values to zero just makes it easier for you, and the animator.
So select all the control curves and go to Modify>Freeze transformations. You should now see all the values in the channel box have been set to zero. It's also good practice to do this with the model as well. This is something the modeler should have done, but it's always good to double check and run another freeze transformation on the model to ensure the values of been zeroed out.
Step 3: Parenting the Control Curves to the Chains
Now is the time when you start to set up the constraints for the mace. The first step is to parent the control curves to the chains. So when you select the control curve, it selects the chain. To do this, select the chain first, and shift select the control curve and either go to Constrain>Parent within the animation menu set, or simply press "P" on your keyboard. You should now see that when you choose the control curve, the chain itself is also selected.
Repeat this same step for all the other chain links and controls. Make sure you select the model first, and then the control curve. You'll also want to parent the ball of the mace, and handle to their corresponding control curves.
Now that everything is parented, you need to change the pivot point. If you select a control curve, you should see the pivot point is directly in the middle, which isn't really what you want. Instead, you want the pivot point to be at the top of each chain link. To change this, select a control curve, and press "Insert" on your keyboard and move the pivot point to the top of the chain link, like you see in the image.
Repeat this step for the rest of the chain links. When it comes to the handle control, move the pivot point to the very front of the handle like in the image.
Step 4: Parenting the Chains
The last step is to parent the chains together. When doing this, you want to think about how the chains should move, and what needs to be the driver. In this case, the handle itself is what's going to be driving the motion of the mace. So you want the handle to control the entire mace.
To do this, select the very last control, which is the control for the ball of the mace, and shift select each preceding control curve, selecting the curve for the handle last. Next press "P" on your keyboard. Now if you choose the handle control you should see the entire rig is selected, and moving the handle affects everything else along with it.
Repeat this step, selecting the ball control first, and shift selecting the highest chain control, and press "P" again on your keyboard. If you select the top chain link, you should see all the preceding controls are also selected. Repeat this again, selecting the ball first, shift selecting each control curve until you reach the second from the top chain link, and press "P." Repeat this step for the rest of the chain links.
Now when you rotate a control curve, it will also rotate the ones below it.
Step 5: Testing the Rig
Once you have the mace fully rigged, it's always a good idea to run it through a few tests, and make sure everything is working how it should. Rotate each control curve, and make sure it's behaving how it should. You can also do a few easy test animations to ensure everything works when you're ready to animate.
That was pretty straightforward, right? With just some clever parenting, we've created a great rig for the mace model, but also an excellent rig to learn overlapping action. If you want to learn how to animate with this rig, check out Character Animation Fundamentals: Overlapping Action, and be sure to visit the Digital-Tutors library for in-depth tutorials in both animation and rigging.