Interface TactileScene

Every mark of the active trace, drawn as an outline.

The mark or marks the reader is currently on, drawn filled.

How much of each mark's interior to raise, where the chart put a value in its fill colour rather than in its shape.

Absent for the charts where fill is decoration — a bar's colour is its series, not its height — because texturing those would fill in the interiors that tell a hollow mark from the solid focused one.

Whether an open stroke gets a dot at each end.

For the charts whose marks are connectors: a dumbbell's bar joins two values, and the values are its ends. Drawn as a bare line the bar says how far apart they are and nothing about where either one is -- a bar whose ends are two pins apart and a bar with none at all are the same thing under a finger. A dot at each end is the value; the line between is the distance.