Skill Level: Advanced 

Linking Hierarchical Animations To Sliders

Introduction...
As you saw in the CycleBranchMorphAddFrame - Pose tutorial, CycleBranchMorphAddFrame is a very powerful function.  What I'll do here is show you how to have sliders control animation rather than simple poses.  The difference between this and the regular Cycle function is that this one works for hierarchies, while Cycle only works for the object it's applied to.
Note: You should complete the CycleBranchMorphAddFrame - Pose tutorial before doing this one because this one builds upon the concepts of that one.  It also uses the expressions that were set up there.

Uses:
Again, the uses are limitless, but one good use is for facial animation.  While using poses, as in the last tutorial, is good for most things, there are certain things that your character might say often, like the names of other characters, or certain words that I can't print here.  You can animate those words and link them to sliders, so whenever you need the character to say it, just move the slider.  Another use would be something that's automated and cycles often but not on a regular enough schedule that you'd be able to make it fully automated, like part of a robot.  So, let's begin...

Getting ready:
1) Set your view to Left, then load the scene called CycleBranch_Starter_Scene.fxs from the Scenes/Tutorials folder.  This will save us a lot of time as opposed to creating a whole new setup.

2)Set the In point to-40  then move the graph over so you can work with the negative frames.

3) Select the Upper_Arm and delete the negative keyframes for it (they're all on Pitch).  Do the same for Lower_Arm.

Setting up the animation:
4) Select the pitch channel Upper_Arm and move the Current Frame Marker to frame -1 and press Create (keyframe).  In other words, frame -1 should now be the same as frame 0.  Do this again for frames -20 and -40 (so frames -20 and- 40 are the same as 0, then repeat the whole process for Lower_Arm.

5)Do a little animation for Upper_Arm and Lower_Arm between frames -40 and -20, being VERY careful not to change -40 and -20 themselves (in other words, the animation should be -39 to -21).  Just rotate their pitch.  In my sample scene, I just made them swinging up, back and forth.

6)Do another little animation for Upper_Arm and Lower_Arm, this time between frames -20 and -1, also being VERY careful not to change -20 and -1 themselves (animate -19 to -2).  In my sample scene, I just made them swinging down, back and forth.

 
Pitch channel for Upper_Arm (left) and Lower_Arm (right) showing the animation in the negative frame area.  Note that the
frames 0, 20, and 40 are all at 0 rotation.  In frames -1 to -20 the arm waves up, and from -20 to -40 it waves down.

7)Set the In point back to 0.

Now you're all ready for the expressions.

The Expressions:
8) Press F3 to expand the left side of the interface, then go to the Command tab and delete CycleBranch_3.  We won't be needing that here.  Later on you can also hide the zpos slider if you want.  Do that on the Values block on Animate.

9) Now select CycleBranch_1.  You will modify this expression to tell it to use the animation between frames -1 and -20 instead of just the pose at -1.  There are two changes you need to make to the expression.  If you remember from the Pose tutorial, arguments 4 and 5 are frame number and the variable for how much of that pose will be applied.  We used -1 as the frame number and the slider's X position (xpos) as the variable.  Now, the frame numbers themselves will be the variable for argument 4, and the application amount (argument 5) will be a constant.  Here's what you do to achieve this:

• Where the expression says-1 (which was the frame number from the old pose) change that to  -1-19*[Slider:xpos]
  What that's doing is applying frames -1 to -20 (because -1-19=20) to the slider's x position channel.

• Where it has [Slider:xpos] (at the end of the expression, not the part you just added) change it to just plain1 .  What you're doing there is turning on the effect (0 is off, 1 is on).

Here is what the final expression should look like:

9)Now select CycleBranch_2and repeat step 9, but use -40+20as the frame range and make the slider channel ypos.  This will tell it that the animation to use will be between frames -40 and -20 (-40 and the following +20 frames).  As you can see, I've done this one different from the one in step 9.  In that one I did -1-19.  But it could have been written as -20-19, because it's the same thing either way.  You either start at -1 and go 19 frames backwards to frame -20, or you start at frame -20 and go forwards to frame -1.  So for this expression you can use either -40+20 or -20-20.  They are both the same thing; like Le Tigre and Blue Steel (but not Magnum).

Here are the final expressions.  Make sure yours match these:

That's all!  Now make sure that the In point is at 0(or higher) and that you're actually at frame 0(or higher), then move the sliders.  You should see the arms move through the animations you created.  Pretty cool, isn't it?

Note:  Remember that it would be a good idea to give the slider channels (xpos and ypos) better, more descriptive names; the Slider itself too.

A completed version of this scene, Expressions_CycleBranch_Anim_01.fxs, is located in the Tutorials\Scenes folder.

Additional information:
General Info - Expressions   General Info - Functions     General Info - Sliders     Meaning of life