I made me some 'fake HDR'-effect, and for convenience, I would like to rig two parameters into a single slider.
unfortunately, I'd like to move the two parameters inverse,
rig slider left: A=0%/B=100%,
rig slider right: A=100%/B=0% ...
I assume, silly simple, but I don't know how ..... ?
A snapshot is a "state" of a project. Say you have a simple rectangle on the screen. Every parameter available to modify that rectangle represents a snapshot. You can assign specific parameters to a sub-snapshot (Rigged parameter — Motion will only save the states that change.) By default, a Slider is set up with two snapshots, a "minimum" and a "maximum" (you can define these for FCPX by changing the Range Minimum and Maximum values in the Options section). You make Motion "record" a snapshot of the parameters you want to change under rig control by clicking on the dots under the slider's control. Below, I've selected the minimum slider snapshot and set the values of two rectangle's whose X-positions I want to control: one on the left side of the screen at -500px and one at the other side at 500px.
[ the highlighted parameters reflect the Object Name + Property as in Move right to left.X uses the name of the layer object (shape) plus the Transform>Position.X property]
Selecting the maximum snapshot, I've reversed their positions for the next snapshot.
All positions in between the two dots (snapshots) are values that Motion interpolates from one snapshot to the other. The only control you have at this point is determining how Motion interpolates between the two values. See the Interpolation parameter set to Linear - you're other two options are Ease [in / out] and Constant which will keep the snapshot state constant until the next snapshot is "met" or crossed, in which case the action will "snap" to the next snapshot. Which leads me to the next thing: if you double click under the Slider, you can add snapshots. You are not restricted to setting values "in between" the minimum and maximum - they can be any legal value (hint) which means you can "program" step states (like a number generator to produce whole numbers without fractional parts.)
The Edit: Start button lets you skip manually adding parameters to the Rig. You set up the rig on a snapshot, click start, and work through all the parameters you want to change as you would normally in the project; click stop when you're finished. Set the next snapshot active, click Start, and make a whole new set of parameters. After you click Stop, move the slider between the two snapshots -- ALL the parameters you changed will now be interpolated between the two sets of changes. You'll also see all the parameters you changed listed in the Rig.
Setting up a compositing effect in Motion to be used in FCPX is a bit "flaky" for lack of a better word. You need to use something "real" to develop with but you've got to "delete" it all before you save as a Final Cut effect.
[Note about using Drop Zones: I have run into problems with Drop Zones and specific media used in Motion having an adverse effect on the Drop Zone in FCPX. I think Apple has fixed most of the issues, just be aware that if you run into trouble, you should be prepared to start over from scratch with an empty Drop Zone all the way through to the final save, so you might have to duplicate all your development work a second time (which is easier now that you can have two open projects at the same time.) To minimize your risk, use media exactly the same size as your project settings.]
Start by adding a Drop Zone (or if you're creating an Effect or Title, just work with the Effect Source or Title Background layer provided), and then immediately clone it for as many copies as you will need for your composited effect. DO NOT clone clones, that has a completely different affect (they will accumulate effects from filters added to them individually.) If you need distinct filter effects on each layer, the clones must be made from the original Drop Zone(/effect source/title background). Do not add filter effects to the original Drop Zone (/etc) (or it will appliead to each of the clones you created as well.)
If you want, and for convenience, you can add the media to its own layer in the project and apply it to the drop zone and deselect it. If you save with the media still in a layer, you can keep Motion from copying it to the FCPX effect Media folder by unchecking Save Unused Media -- or whatever it's labeled; but you should drag the source out of the Drop Zone 'source well' before saving. At a certain point, you can forego the temporary media and add the finishing touches by going back and forth between FCPX and Motion - every time you save from Motion, it will be updated in FCPX (you will still have to drag a new copy onto a clip [or add the title to the storyline - which is easier because you can drag to replace a title but you have to delete or turn off the "old" instance of an effect when you add the new updated version... or you'll get both copies on the same clip.])
Instead of this:
layer#2 negative, desaturated, blurred, compositing mode Overlay,
Filters > Stylize > Highpass mode Overlay instead (you can still add negative if needed.)
also try adding Gaussian blur to the third layer and ramping it up > 100... just for grins. Allow Hard Light, Soft Light and Overlay as variants to Linear Light (you can create a "pop-up" rig, Add the Blend Mode parameter to the pop-up and only allow those options to the user by publishing the pop-up rig.) Other possible options to consider might be: Add, Screen, Color Dodge, and Color Burn, but experiment with all of them (except for Stencil Alpha and below... they won't be much use in an effect like this.)