well I can see someone didn’t buy my book
but here is how I like to look at it in a nutshell: you have two aspects to a relationship: the driver and the driven. the driver can be any animate-able attribute (like you discovered with the transparency) this attribute can Drive the properties of any number of other attributes, or even (and this is keen) other drivers!
so think of the Driver as a timeline every discrete value of that property acts as a potential keyframe, on which you can store the properties you want to alter. a bone for instance has three (all rotational relationships seem to be represented as eular for easy editing and comprehension) axes of rotation where each possible combination of those axes can hold different relationship data. this is smartkin.
A pose slider is what is now termed a “user defined” property, this property can be either a Percentage, a Boolean (on/off) or a folder to collect other properties for organization. a Percentage is kind of a misnomer as the values that it can hold can be any range of numbers not just percents. you can change them as you see fit. for instance, to change a rig you might just want say a range of -3 to +3 as this will often be more than enough to swap a rig out (or even less if you like ) each value can drive a set of sliders to turn on or off constraints and show or hide bones.
And this is just for starters.
the layering and nesting possibilities are mind boggling. for instance: I have a character with Hakama Pants, now I drive the initial surface of the pants with cloth simulations using Dinocarl’s suspension CP techniques. is it perfect? not yet. now I need to distort the cloth shape based on the motion of the leg (since I don’t want to rely on collision detection) I do this by taking a bone and orienting it to the leg, this is then lagged by one frame (giving me a measure of roughly how fast the leg is moving (ie the further behind the lag bone is the faster the leg moved in that frame) and in what direction (ie away from the lag bone)) I can tell then the difference between those two bones and use it to drive a pose with an expression. the value of that pose in turn can drive other poses that distort the mesh to compensate for the leg motion… is this perfect? no but it’s so close I can taste it Carl and I have tossed around some ideas but I’ve tossed it on the back burner so I can work on other aspects of the short.
really what you can hook up to what is just fantastic, and it’s all pretty visual… as artist friendly as I’ve ever seen this particular feature (maya calls it set driven keys and it’s not as much fun to play with )
Hope that’s a help,