So I've come to realize that the ModMapper in "Map Smooth" mode basically maps any modulator onto a piecewise linear curve, which is actually incredibly useful. I had previously thought it's the same as "Map Quantize" with some slew limiting (or filtering) applied, which is not nearly as useful, but using the wonderful new Scope viewer has opened my eyes. This way you can have a mod source travel though a number of fixed "stations" while "lerping" in between them. Super cool.
There's a little problem with this though which I'll try to demonstrate with a simple example. Let's say we'd like the modwheel to open a filter all the way in the first half of its travel and then halfway close the filter in the second half. In midi CC terms it's like if we linearly mapped the modwheel range of 0-64 onto 0-127, and the range of 64-127 onto 127-64 (not sure if that helps, but I'll add a picture later). So we'll set the modmapper to Map Smooth with ModWhl as the source, set the number of steps to 3, and then set the first step to 0, the second to 100, and the third to 50 (and obviously modulate filter cutoff with that modmapper). This ALMOST works exactly as I described, except it actually maps the range onto 3 segments rather than 2, with the last segment just outputting the constant value of the last step.
For the following screenshot I set the modmapper source to a rising saw lfo to hopefully make it obvious what the modmapper is doing in the scope. As you can see, in the first third it rises from 0 to 100, in the second third it decreases from 100 to 50, and in the final third it just sits at a constant 50.
What I would have expected (or preferred more accurately) is for the first and last steps of the modmapper to be treated as endpoints of the transfer function, such that if you have n steps there would be n-1 segments. But maybe that's just me! I'm afraid that changing this behavior might make some presets sound a bit different but hopefully it's early enough in development to be acceptable.
As a side note, if the modmath X parameter went higher than 1 you could fix this by multiplying the modwheel by 1.5 and the using that as the source for the modmapper but that's another FR for another post...
