How to bind to component fields within a constraint?

Suppose I had a simple component like so:

public class CoolComponent : MonoBehaviour {  public float coolMultiplier; }

And let's say I wanted to write an Animation Rigging constraint that did the following:

targetObject.position = sourceObject.position * sourceObject.coolMultiplier;

How would I accomplish this?


IDEA #1:
I could try giving the IWeightedAnimationJob two fields:

Code (CSharp):

1. public ReadWriteTransformHandle targetObject;
2. public CoolComponent sourceObject;

But of course that won't work--it'll end up throwing a "Job structs may not contain any reference types" error. Makes sense; the job shouldn't be passed the entire CoolComponent by reference.


IDEA #2:
I could try binding my job like this:

Code (CSharp):

1. // IWeightedAnimationJob
2. public ReadWriteTransformHandle targetObject;
3. public ReadOnlyTransformhandle sourceObject;
4. public FloatProperty coolMultiplier;
5.  
6. // IAnimationJobData
7. public Transform targetObject;
8. public CoolComponent sourceObject;
9.  
10. // AnimationJobBinder's Create method
11. targetObject = ReadWriteTransformHandle.Bind(animator, data.targetObject.transform)
12. sourceObject = ReadOnlyTransformHandle.Bind(animator, data.targetObject.transform)
13. coolMultiplier = FloatProperty.Bind(animator, data.sourceObject, "coolMultiplier")

This compiles and runs, but it seems the coolMultiplier field always evaluates to 0.0f within the job, even if it's set to a different value. I couldn't find a combination of attributes that would actually get the animation job to properly pick up the coolMultiplier's true value.


IDEA #3:
Same as above, but try binding in the AnimationJobBinder like such:

coolMultiplier = FloatProperty.Bind(animator, component, "m_Data.sourceObject.coolMultiplier")

That just reults in a "The PropertyStreamHandle is invalid" error.


IDEA #4:
Add the following to the IAnimationJobData:

public float coolMultiplier { get => sourceObject.coolMultiplier; }

And then try binding to that in the AnimationJobBinder as follows:

coolMultiplier = FloatProperty.Bind(animator, component, PropertyUtils.ConstructConstraintDataPropertyName(nameof(data.coolMultiplier)))

This just results in another "The PropertyStreamHandle is invalid" error.


So what's the right way to make this work? And as a follow-up question, what's the best way to actually learn the ecosystem of the Jobs system and the Animation system and the Animation Rigging package. I've watched tons of great Unite and GDC talks on the subjects, I've seen the rad Unity announcement blog posts, and I've browsed through the (often very sparse) documentation... and honestly I still feel like I can't answer most of my own questions. What's the best way for a developer to actually learn all of this stuff both at a conceptual level and at a practical programming level?

 

Is there a way to do this without assuming the FloatProperty is animated? I assume that may be preventing me from modifying the base property.

In my case, the FloatProperty is set through code or the inspector, but FloatProperty doesn't seem to update once it's initially bound using Bind