Multiple shape keys triggering at the wrong time causing unwanted deformations

Question

I am trying to use corrective shape keys to fix my characters elbow deformations However when I try to use two shape keys together they cause bad deformations On the elbow of my character, I tried to add 2 shape keys, both with drivers: One for the first part of the deformation and the other for the second part However the second shape key triggers at the same time as the first one causing unwanted deformations I am unsure how to solve this issue! Help would be much appreciated Thanks, Beni

Answer 1

If two shapekeys don't look good when used in conjunction, then don't use them in conjunction.

If you have a shapekey you'd like to turn off when another shapekey is being triggered, you can use a scripted expression for the driver, add the value of the other shapekey as a variable which we'll call var2, and use a scripted expression like, "var * (var2<=0)", which will turn off the shapekey the instant that the other other shapekey is triggered. There's no interpolation there, but you haven't specified what kind of interpolation you'd like; if we use "var * (1.0-var2)" then we'll smoothly interpolate between regular triggering and no triggering, as var2 ranges from 0 to 1.

Generally, what you'll want here is a third shapekey for when both trigger, manually created. It might be simplest to consider creating custom properties, driven by the same drivers as your original shapekeys; then, you can trigger the third shapekey by something like var1var2, the first shapekey by var1 -(var1var2), and the second shapekey by var2-(var1*var2), for simple, linear interpolation between all three. Custom properties are not strictly necessary, you could use empty shapekeys instead, and it could be created in a way that didn't require any "temporary values" like this, but temporary values make it easier to understand what you're doing.