Rigging Bones? Please Read Carefully
patlane last edited by
I'll return next week with how to deal with ghost bones. Hint: it's basically the same as regular bones but with the affected actor step first.
Thankyou Tenyon, a real step by step guide. you made it very easy to understand. Waiting for your ghost bone tutorial. Thankyou again. Pat :)
Glad it's helpful.
Now, Ghost bones are interesting because they are bones that have no assigned geometry at the outset. What this means is that you can't use the Select Tool, translate tool or any other tool to directly select the bone. Instead, you have to select it from a pulldown menu. See the image for an example of how I selected the ear ghost bone.
Now I have the bone selected but if I move the X, Y or Z Rotate, it's not just affecting the area of the ear, it's affecting the entire head. Obviously, this is undesirable behaviour, so we'll need to paint some weights to control how much of the head is affected. Once again, we'll want to use the deformers to help get us started. I'm going to work with the xRotate, which is the twist for my model's ear.
Twisting the ear with the xRotate shows that while the affected area is now lessened, it is still grabbing more than what should be moved, so we'll need to make a weight map.
Using the Subtract and Smooth options on the weight painting tool, I remove the unwanted vertices from the weight map and then smooth the area of where the wanted vertices and the rest of the head meet. This is done just to improve the look of the motion a bit.
Now that we have the twist setup we can use a nifty feature in the Weight Map editor to copy the weight map from the Twist and paste it into our other rotations for the ear to help speed things up. So at the bottom of the Vertex Weights window, you'll see a button that says Copy/Paste. Hit the button and choose Copy.
Close the Vertex Weights window and then switch to the Y rotation for the ear. Now open the Vertex Weights window by hitting the paint brush in the Joint Editor and this time hit the Copy/Paste button and choose Paste.
Once you've done that, test the motion of the Y rotation on the ear. In my case, it bends in the middle of the ear instead of at the point it joins the head.
To my taste, this is not desirable behaviour (note that some of what is "right" is a matter of taste in rigging). Now I have a few options. Simplest: I can edit the weight map so that the ear is more fully influenced than it currently is (ample use of Add and Smooth). I can delete the Weight Map, alter the position of the inclusion/exclusion lines of the deformer and then try again or I can decide to leave it as is. I'm going to delete it and start over.
When working in 3D, be it designing, modeling, texturing, rigging or animating, it's important not to treat your work as too precious to alter. You have to be willing and ready to scorch the earth and start again if needs be - though rarely does such a need arise. Usually you'll find that there may be a better way to do something and you will always have that option to explore if you wish. Of course, if you're on a deadline and working for an employer, that allotted time may be greatly reduced, in which case you'll have to do what you can with the time you have. Regardless, be prepared to make changes.
So to start, I zero rotations and hit the Delete option for the weight map. Then I adjust the inclusion and exclusion lines so that they include more of the ear while excluding more of the head. It still won't be perfect but that's ok. I'll clean it up in a bit.
Now I'll choose Add and Merge Zones to Weight Map. Then I'll do a quick test of the motion to spot just how good or bad the current weighting is. Based on the way the vertices are highlighted, I'm guessing the lower part of the face is going to move more than I want...
Sure enough, it does but it also is moving with a pivot exactly where I had hoped it'd be (the connection from head to ear) as opposed to where it had been moving previously (the center of the ear). Now I just need to use the Subtract option for the weight painting and remove the lower part of the face I want to keep static.