About a year ago, I launched a tool to help out with the Blend Shape pipeline process I went through with my characters for Bean Caught and thought I’d share it with the web. Today, I dusted this off, for yet another film I’m working on, and not only decided to update it, but to also post a tutorial on how to use it. You can download the latest version here: McBe BS Tools v1.10!
Again, the reason why someone might want to use this tool is help reduce the amount of steps in creating blendshapes than it would usually take to breakdown vertex placement on geometry for, say, both sides of the head so you have individual nodes to play with. With this method, we’ll be using Paint Blend Shape Weight Tools to accomplish the goal of creating two perfect halves that blend back together when we re-add the geometry to the model. The following steps assume that you have created Blend Shapes and added them prior to this step so that we can break them all down into smaller components to re-add them back to the final rig.
Select your model, then the Paint Blend Shapes Weight Tool. We’ll want to work on the first node listed in the index which will be the default Blend Shape Envelope. It’ll be named whatever you named your Blend Shape DAG – which typically defaults to blendShape1 when you add your morphing objects.
With your model selected, you’ll want to head over to the Input Channel Box side of the screen to set one of your existing blend shapes to 1.
Once you set your chosen blend shape to work on, head back over to your model and start painting on the envelope node as pointed out previously. What we want do is set our brush to “Replace” and then set the value to “0″ so we can remove what we don’t want to have on one side of the model.
After you’re satisfied with the half of the model you painted, you can simply bring up the tool to invert the paint weights and/or duplicate the model with the options listed. They are pretty straight forward as they displace the geometry so when they duplicate the left and right sides, they are not on top of each other. You can also choose to rename them. For this case, we’ll duplicate AND add the geometry back to the main model so we can continue inverting the blend shapes to break them down even more.
Once you set your options, it’s as easy as hitting the button. Once you do so, the geometry will be duplicated with the current settings for your blend shape and then inverse of what you painted. This way, you can set the shapes aside so you can continue breaking them down and re-adding them later if you’d like.
Once you are done going through your blend shapes, you’ll want to remember to go back to the envelope node under the Paint Blend Shapes Weight Tool and we’ll want to flood it with the brush set to “Replace” and a value of “1″. This way, when we use the blend shapes attached to the model, it will allow for morphing to happen on all points of the geometry instead of just the painted ones. This is important to remember, otherwise you’ll be confused why half your face doesn’t work!
After you restored, go back to your new blend shapes on your model in the Input section of the Channel Editor and play with them to see their now perfectly inverted shapes working together!
Keep in mind that this tool does not mirror, but inverts, which means you can go back to these shapes and break them down even more. In my workflow, I will then probably continue this process until I have 6 or 8 shapes of the eye brows done. If you’re smart and do things right, you could reduce your work and duplication time even more by just painting one half of the body and flipping your BS numbers in the Input node from 0 to 1 and back to 0 to move onto the next one in line. By doing this, you’ll halve your work very quickly. Feel free to leave feedback and comments – enjoy!