Re: glide between 19tet tones
i usually work on the linear layer when dealing with note event, so a 19tet scale would simply contain floating point note numbers such as 64.3765.
the key for building a glide or portamento mode then is, in my opinion, to first go to the signal layer, then doing the mtof~ there as last step after the (possible) glide. this way it is very easy to perform linear (or distorted versione of linear) portamento fades, and it is also easy to implement different key modes for it.
if you plan to implement vibrato, too, that can be done the same way, and i would suggest to do it _after the gliding
you said line~ would truncate the input? … it shouldnt. there must be something else wrong in your patch, line~ would be the right way.
a simple example for my model suggestion in the picture below. this is how i drive a line~ object from incoming note number messages, which creates a signal representing the above mentioned note number of 64.3765 on the signal layer – including the portamento offset.
you can also easily use this as a poly~ patcher to add further modes, such as "use highest note in a chord as trigger" or whatever.
it has 4 modes: off, on, only up, only down.
possible scaling of the time values must be done outside before going into the rightmost milliseconds inlet.