There isn't a way to interact at that level with line-of-action. There are a couple things I can suggest as workarounds and a couple ideas for how we might change the software in the future to better suit your needs.
- Get line-of-action working as best you can, then use the zFiber.excitation attribute for any corrections you want to add on top. This provides a lot of control, but puts it all in your hands. How you control zFiber.excitation is up to you.
- Stop using line-of-action. If you want really detailed control over how the muscle excites, then you may prefer to use your own expression/ramp/whatever to go from curve length (or joint angles, or whatever) to the zFiber.excitation attribute.
Possible new features:
- As you suggest, we could add a user-provided ramp to remap the line-of-action's excitation before using it.
- Leave LoA exactly as-is, but provide a tool to bake out its values onto some animation curves. If you're uphappy with what it's doing, you can bake it out and tweak the curves as you see fit.
- Make zLineOfAction have an output attribute for its computed excitation. Then you can stick your own remap or expression or whatever after this and then connect it into zFiber.excitation.
For both the workarounds and the new features, some are better in some situations and some are better in others. For example, depending on how much control you want, or depending on if you're doing just one shot or building a completely general setup. Probably other things too.
How do those options sound to you? Is that any help right now?