移调乐器场景下按实际音高为特定音域外音符上色的问题

你的问题核心在于：当前代码通过ly:pitch-semitones获取的是记谱音高的半音数，而移调乐器谱表经过\transposition处理后，记谱音高和实际音乐会音高存在偏移，导致颜色判定逻辑失效，两个谱表的音符颜色无法匹配。

解决方案 #

要让颜色判定基于实际音高而非记谱音高，需要获取谱表的移调偏移量，将记谱音高转换为音乐会音高后再进行半音数计算。

修改你的clarinet-range函数如下：

#(define (clarinet-range grob)
   (let* ((pch (ly:event-property (event-cause grob) 'pitch))
          ; 获取当前谱表的移调偏移量
          (transp (ly:staff-transposition (ly:grob-parent grob Staff)))
          ; 将记谱音高转换为实际音乐会音高
          (concert-pch (ly:pitch-transpose pch transp))
          (semitones (ly:pitch-semitones concert-pch)))
     (cond ((and 
               (>= semitones clarinet_amateur_low)
               (<= semitones clarinet_amateur_high) 
               ) black)
           ((and 
               (>= semitones clarinet_pro_low)
               (<= semitones clarinet_pro_high) 
               ) darkyellow)
           (else red))))

代码说明 #

1. ly:grob-parent grob Staff：获取当前音符所在的谱表对象
2. ly:staff-transposition：提取谱表的移调偏移量（比如降B调单簧管的偏移量为-2半音）
3. ly:pitch-transpose pch transp：将记谱音高pch转换为实际音乐会音高concert-pch
4. 后续的颜色判定逻辑保持不变，但基于实际音高的半音数执行

完整修改后代码 #

#(define clarinet_amateur_low -10) % D3
#(define clarinet_amateur_high 29) % F6
#(define clarinet_pro_low -10) % D3
#(define clarinet_pro_high 34) % A#6

#(define (clarinet-range grob)
   (let* ((pch (ly:event-property (event-cause grob) 'pitch))
          (transp (ly:staff-transposition (ly:grob-parent grob Staff)))
          (concert-pch (ly:pitch-transpose pch transp))
          (semitones (ly:pitch-semitones concert-pch)))
     (cond ((and 
               (>= semitones clarinet_amateur_low)
               (<= semitones clarinet_amateur_high) 
               ) black)
           ((and 
               (>= semitones clarinet_pro_low)
               (<= semitones clarinet_pro_high) 
               ) darkyellow)
           (else red))))

notes = \relative c {
    \key c \major
    c4 d e f g a b c d e f g a b c d e f g a b c d e f g a ais b c
}

\score {
    <<
        % concert pitch
        \new Staff {
            \override NoteHead.color = #clarinet-range
            \notes
        }

        % transposed pitch
        \new Staff {
            \override NoteHead.color = #clarinet-range
            \transposition bes
            \transpose c d \notes
        }
    >>
}

修改后，两个谱表的音符颜色会完全一致，因为颜色判定逻辑统一基于实际音乐会音高执行。

内容的提问来源于stack exchange，提问作者Simão Leal