one finds the code
a = Disk[{0, 1}];b = Disk[{-0.5, 0}];c = Disk[{0.5, 0}];subsets = Subsets[{a, b, c}, {1, 3}];subsetscolors = Map[Function[{c}, Blend[Flatten[Map[Table[Map[Append[#, 1.5/Length[c]] &, c], 2] &, c]]]], Subsets[Map[ColorData[112], Range[3]], {1, 4}]];RegionPlot[Evaluate[DiscretizeRegion[RegionDifference[BooleanRegion[And, #],BooleanRegion[Or, Complement[{a, b, c, EmptyRegion[2]}, #]]]] & /@ subsets], PlotLabels->Callout[(StringJoin @@@ Subsets[{"A", "B", "C"}, {1, 3}]), Center],Sequence[PlotStyle -> subsetscolors, BoundaryStyle -> Directive[Thickness[0.01], White], Frame -> False, LabelStyle -> {24}, PerformanceGoal -> "Speed", ImageSize -> 450]]
to "Use PlotLabels to label a three-set Venn diagram in RegionPlot".
My first question is whether this can be "upgraded" to a 3D-scenario in which Sphere is employed instead of Disk?
Probably, a "tall order", I would imagine--well beyond my capabilities/understanding, in any case.
Also, can such codes be applied to non-"Basic Geometric Regions"? (My ambition would be to use the 3D regions specified by the constraints A, B, C at the end of Create a Venn and/or related diagrams given the eight atoms of a three-set (A,B,C) 256-dimensional Boolean algebra