I've started using the automatic part combiner as part of my SATB hymnal/psalter work. It simplifies my life tremendously, and the default works well except for two situations:
1) Where the voices are more than an octave apart (eg., between tenor and bass), since it separates the voices
2) Where the voices are an enharmonic unison or second apart, since it creates a unison or a chord, respectively, and I want two stems on the voices.
I know I can on an individual basis use the chord or apart configuration commands to manually override the behavior at these points, but I'd like to create a new "automatic" behavior" that handles these two situations "correctly," to avoid a lot of markup cruft and manual rework in the actual part definitions (and as a selling point to others who might use my template for the same purpose, so that they don't have to worry about it because the default behavior will be correct).
I have gone through the scheme file that defines the \partcombine function and found the line of code that addresses the first issue (I think it's line 266). I can change the 8 to an arbitrarily high number and get what I want.
That leads me to two questions:
1) How do I get the function to look at the interval and separate the voices if the interval is less than a third? Is there a way to flip the section of code that separates the voices if the interval is too large and make it separate if the interval is too small?
2) How do I/can I reference a copy of the default part-combiner file (with my customizations) to override the default part combiner?
A side question is a matter of style. The hymnal I'm using as a style reference has all stems pointing away from the middle of the system (Except when two stems are being used), instead of automatically directing the stems (so treble clef stems point up, bass clef stems point down). will the default \stemUp command work in this instance or is there something else I need to do to make that functionality work?
Thanks,
Carl