LegendGroups.hpp

Which field legends show, and in which order (construct-fea-solve §FEC-5).

Detailed description

collectLegendInputs() reads the visible colored items of a scene once, on a change. groupFieldLegends() is the pure rule that turns them into the legends that show: items with the same field, range, colormap and unit share one legend, the selected item's legend is first, then tree order, and at most three show. The corner HUD of the shell (construct::ui::FieldLegend) and the OPAL task `construct.view.legends` call the same two functions, so a plan sees what a person sees.