I’m afraid the annotation angles are not responding to -B+a either. The GMT.jl port of ternary is way more reach but it seems not able to do this too. See examples at
One thing I wanted implemented was a way to set the annotations angle follow the direction parallel to the axis is respects.
My (semi-failed) attempt with GMT.jl (Vd=1 makes it print the generated GMT command)
ternary([NaN NaN] , marker=:pt, labels=("A", "B", "C"), B="aafg+a0", Vd=1, show=1)
psternary -Baaafg+a0+lA -Bbaafg+a0+lB -Bcaafg+a0+lC -R0/100/0/100/0/100 -JX15c --MAP_GRID_PEN_PRIMARY=thinnest,gray -Sp2p
