Evaluación Actuarial

Chapter Example Files:

chpt6-Octopus_Blendshape_Start.ma; chpt6-Octopus_Blendshape_Start.mb; chpt6-Octopus_Blendshape_Completed_v1.ma; chpt6-Octopus_Blendshape_Completed_v2.ma; chpt6_medusa_start.ma; chpt6_medusa_v2.ma; chpt6_medusa_v3.ma; chpt6_medusa_v4_Completed.ma; chpt6-OffsetControl_example.ma

This is our last little rig together before we launch into the biped. Are you excited? My, how far you have come. Instead of repeating the rules, I’ll list some handy notes I had lying around:

Note: When adding constraints to joints or IK handles: maintain offset must be on.

Note: Once you place your controller and add a constraint, you cannot adjust the pivot point of the

controller unless you want your rig to suffer a horrible crippling disease only cured by swear words and the undo button.

Note: IK handles can be frozen (you have to temporarily turn Sticky OFF in the attribute editor)

but I’m always afraid the universe will rip apart. I’ve never seen it break something but I might be causing small black holes somewhere.

Note: If you use the duplicate tool to duplicate a controller, like a foot or hand controller, a trick is

to duplicate (CNTRL d) then move the pivot point to the origin. Scale in -1 in X. That will flip it. Freeze and modify>center pivot. Watch out if you duplicate constraints they will show up in the outliner but do not work. Do not copy and paste—that’s nasty.

OK, we’re ready for our last topics. With these, you will have gained the keys to the kingdom, because with these you can do anything. Our two topics: blendshapes and set driven key.

We’ll start with blendshapes. Blendshapes are very useful, especially for facial animation. Raising eyebrows, closing eyelids, smiles, phonemes, lip sync types of things. Other uses are for corrective blendshapes, for example when an arm is bent and you want the bicep to bulge or a vein to pop out or you open the mouth and make double chins. In this chapter we will look at the basics of blendshapes to get you started.

This is a full-time job for a modeler and a rigger team and can take up lots of time to get it right. If you don’t have the blendshapes your character needs then your character cannot act except with body language. I would suggest reading Osipa’s Stop Staring: Facial Modeling and Animation Done Right (see Epilogue) to get the fuller picture once you are comfortable with these basics.

A lot of time is generally spent between the animator, character designer, modeler, and rigger to get the blendshapes just right. Blendshapes themselves can be sculpted in ZBrush, for example. Though I love ZBrush, for this book we’ll stay in Maya for the basics.

Open Chpt6-Octopus_Blendshape_Start.ma. This file has one character in the center of the screen labeled Octopus_GEO. He is frozen and has the history deleted. This is the main character. We want to make three blendshapes: Happy, Sad, Angry. We will create duplicates of the main character and sculpt the faces to be Happy, Sad, and Angry. Then we’ll set up sliders so that we can turn on or off these blendshapes.

1. Select Octopus_GEO then create three duplicates by clicking CNTRL d or Edit>Duplicate

three times. Move each duplicate behind the main character or somewhere off to the side.

2. Rename these duplicates: Happy_BS, Sad_BS, Angry_BS. Very important—label them

now. If you wait till later, it will be too late to get proper labeled attributes. (You’ll see.)

3. DO NOT FREEZE … DO NOT FREEZE … I said, do NOT freeze transformations on

these blendshape targets.

4. Do NOT move their pivot points. Maya needs to know that offset information to calculate

the vertices movement.

To sculpt the blendshapes you want to adjust them at a component level. Meaning, move the vertices, use the sculpt geometry tool, the soft deformer tool or any type of deformer to create the sculpt that you need. Scaling the overall geometry will not make any effect—that is adjusting the transform node. You want to adjust the components themselves. If you use the soft modification tool, it might have the history turned off. If the history is turned it on it will leave behind an “S” handle that you could adjust.

Another thing to remember is that you should not create your blend-shapes until you have finished

modeling the main character. We’ll talk about what to do if you need to fix some geometry in a

second.

1. Sculpting is completed having used the sculpt geometry too, soft deformers or by moving

vertices or components.

2. Select the blendshapes (Happy_BS, Sad_BS, Angry_BS) by holding shift and clicking on

them, then select the main character (Octopus_GEO) last. The Octopus_GEO character will be green and all of the blendshapes will be white. Super important, if your main character is not green your blendshapes are going to be hooked up incorrectly.

Figure 6.1 Creating a blendshape. Octopus modeled by Brenda Hathaway.

3. Animate>Create Deformer>Blendshape. Select the option box. Reset settings to the default

4. You can give it a name there in the box (I like to name it): emotions. Click create. This will

create a blendshape node. Select Octopus_GEO and in the shapes area of the channel box click on the new node “emotions” and it will open up showing you an attribute for each of the blendshapes.

The name of these attributes came from the name of the blend-shape target geometry. So, hopefully you renamed them when you had a chance and they aren’t called Octopus_GEO1, Octopus_GEO2, Octopus_GEO3. That will be difficult to hook up and remember what they are.

These virtual sliders adjust from 0 to 1 to turn the blendshapes on and off. You can turn on a blendshape and continue to sculpt the blendshape targets since they are connected via history. You can even turn on more than one blendshape at the same time. Beware when you do this, if a vertex was told to move.5 in X by both blend-shape targets then it will move 1 in X when both blendshapes are turned on. This might cause a multiplication of movement that you don’t intend.

Just as a side note, you can also type in numbers bigger than 1 and the blendshape will continue to adjust the vertices based on the original way that they were being moved. That can be a good thing to give the animator, when you put a controller onto these attributes. Perhaps they might want to push the blendshape just a little bit further than what was created.

If you need to adjust the geometry even after you have made the blendshapes and connected them, you can. For example, if you add in a nose by extruding a face then select the main character and go to

Edit>Delete by Type Selected>Non-Deformer History that will delete the extrude node and then

flow the extrudes down into the blendshape targets automatically in newer versions of Maya (2011+). In older versions of Maya you need to select the main character and click Animate>Edit

Blendshape>Bake Topology to Targets.

Note: Often I have students who want to cut off the head of the geometry and only sculpt that. It

doesn’t work since the blendshape looks for the vertex number to see how far vertex 5 moved. If you cut off the character’s head the vertices are renumbered. There is an advanced way to do this using a wrap deformer. Kunzendorf wrote of it in Mastering Maya 7 (Kundert-Gibbs et al., Sybex, 2007). However, I’ve had that method fail on higher-res geometry.

There is a window in Maya to adjust blendshapes under Window>Animation Editor>Blend

Shape. This has sliders for each blendshape attribute all under the one node. This window allows the

option of keying, deleting etc. of blendshapes. I don’t see this window used too often. It was used a lot around version 1 of Maya and was demonstrated at SIGGRAPH ’96 as they used it on Dinosaur. Disney used this window in a proprietary way that showed an image next to each slider for what type of shape it was. As far as I know, not many people use this window anymore. I’ve only seen onscreen controls for animators used. Personally, I have had many files get so many blend-shapes that the blendshape window couldn’t handle it. In those files, if the blendshape window was left open when saved the file would be unable to open because the window would freeze up. Those might be old bugs, but in class we use other methods.

You can delete the blendshape geometry after the blendshape is created; the math is saved. I personally like to keep them there so that I can still sculpt. At some point you can delete them to make the file lighter. You can always regenerate them by dialing in the blendshape and duplicating the geometry. You can even do this to create new blendshapes. If you turn on the blendshape for Happy and Angry, select the geometry and Edit>Duplicate. Move this new shape to the side and name it

Cranky. Select Cranky and then the main geometry. Edit Deformer>Blendshape>Add blendshape.