Layout options>Note Spacing. Spacing behavior of multiple voices with adjacent noteheads

In this situation, the 8th note’s spacing changes according to the Layout Option’s Note spacing value (Default space for quarter note). Is this a correct behavior? Please compare the beam length of the 8th note in the 3rd bar with those in the 1st and 2nd bar. In the 1st and 2nd bar, as Note Spacing value in Layout options decreases, beam length of 8th notes shortens (i.e., space between 8th notes decreases).
I think it’s better to be that the spacing of the 8th notes does not change, and length of all 8th note’s beams in any bars keep the same, no matter how Note Spacing value changes.
Untitled Project 8.dorico (657.7 KB)

This is definitely correct behaviour. The space for a quarter/crotchet is scaled proportionally for other note values (to the ratio specified further down the dialog). There’s a dynamic illustration that tells you how much space Dorico is allocating to each note value.

When you have a staff that is less than 100% full, Dorico has to put the extra space somewhere. If you turn the default space for a quarter/crotchet right down, such that the staff is only 57% full, that 43% empty space has to be equally spread throughout the system.

The other thing that you’re seeing is that in bars 1 and 2 the upstem crotchets/quarters are in Voice Column 0 - they are defining the start of each crotchet/quarter beat - and the first of each pair of downstem quavers/eighths is in Voice Column 1, so slightly to the right of the start of the beat.

Thank you for a reply, @pinoleo.

I still have doubts if Dorico’s justification algorithm in this case is correct.
I’ve changed “Only justify final system in flow when more than x % full” in Layout Option>Note Spacing to 100 % (i.e. deactivating justification), and tried the same work as the previous post. Then, no matter how “Default space for quarter note” value changes, all 8th note’s beam length in every bar are kept equal (I’ve checked with a ruler.).
So, shouldn’t all 8th note’s beam length in every bar be equal after justification too?

(without justification)Untitled Project 8.dorico (657.7 KB)

No. Justification is a very standard compromise, and spreads fairly evenly.
I’m not quite sure how to make this clear.

The length of the beat indicated on the left in blue is about 10% wider than the beat on the right (in blue), to account for the extra space added by the upstem voice.

If Dorico shortened each of the beams in the second bar (bar 3 in your example) there would be a ridiculous amount of white space between each beat, i.e. the green line would be substantially longer than the orange line.

Are you suggesting that the orange and green lines should be different lengths to each other, and if so, why?

It’s off the subject of requesting constant equal 8th notes spacing throughout a system, but I would like to ask a more fundamental question. I would like to know Dorico’s calculation rule that makes a difference between the two blue arrows (left and right) in your picture. How Dorico created the ratio (you say “about 10% wider”) of the blue arrow on the left to the arrow on the right? And is this ratio always the same, no matter how the ”Default space for quarter note” value changes? It doesn’t seem that. Or do we always get a constant answer by subtracting the length of the right arrow from the length of the left arrow, no matter how the ”Default space for quarter note” value changes? Again,It doesn’t seem that.
The example below has four systems. Each system has the same music content, but ”Default space for quarter note” values are different using Note Spacing Change, these values are 5, 4, 3, 2 from the top to bottom system.

As we can see, the spacing result of each system is subtly different.
I want to know why these differences occur, and what formula would Dorico use for justification (i.e. spreading empty space throughout the system) to make such differences in these cases.

(four system_Note Spacing Change)Untitled Project 8-01.dorico (372.8 KB)

No. Of course, these lengths ​​must be the same, since these have the same note value (8th)

The short answer is that I don’t know.

I note that if you put all the downstem notes in Voice Column 1, there ceases to be a difference between the top three systems, regardless of the different Note Spacing settings. The bottom system is then less than 50% full so squishes together

Referring back to those blue arrows, the one difference is the adjacent noteheads, and the gap between those is fixed in Engraving Options. That gap is never going to widen regardless of what the Note Spacing Options are set to.

I doubt you’ll get a simple to answer to this question, if an accurate one is forthcoming at all (which it may not be, seeing as it’s not explicitly explained within the program).

I see.
I hope the Dorico team can explain it!

They can, I’m sure. The question is whether it’s commercially sensible for them to release that information.

There are certainly some special cases in Dorico’s spacing algorithms that perform some optical adjustments in specific situations, and one of those situations is where you have the notehead that governs the rhythmic space offset from the start of the rhythmic space for that beat. I’m not sure how much more I want to say about it, really, except to say that this behaviour is deliberate and is intended to produce spacing that looks even visually, even if in fact there is technically some distortion going on.

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I’ve also come across this issue and I think I reported it to Daniel some while ago as being undesirable in some situations. For instance, using the example provided, imagine a piece for orchestra where every stave has continuous quavers except for one which has the offset crotchet/quaver noteheads. I would rather go with the majority and give those staves standard even spacing, with just the one odd stave consequently having less than ideal spacing.

Thanks for a reply, @dspreadbury.

I see (Until now, I was thinking that it was a kind of unintentional bug ).
But if this behaviour is a deliberate and intended optical adjustment, why is this adjustment not done to the same music before justification (like a GIF in my second post)? And why, even after justification, the results of the optical adjustment are different depending on the “Default space for quarter note” values (like an example in my third post)?
I feel that the behaviour of this optical adjustment is not unified and may cause trouble.

It is indeed something that you’ve asked about, @Jeremy_Aknai, and we have a task on our backlog to add an option to allow whether it should be enabled or disabled for a particular layout (or indeed from a particular Note Spacing Change). I can’t say when this will be added, but it’s on the backlog.