Colour Scales

The ramps every display paints magnitude with and the two wheels a harmony display paints pitch with, as pure functions. The ramps are the real multi-stop scientific colormaps from d3-scale-chromatic (viridis, magma, inferno, plasma, cividis, turbo), tabulated once into 256-entry lookups, plus grayscale and heat. The pitch wheels give each pitch class a hue by semitone or by circle-of-fifths position, measured from a tonic so a key keeps its colours when transposed; drawn on a pad layout, the wheel whose hues run smoothly across the pads is the relationship that layout makes visible.