Gothic window glass of the Chartres generation. The colour is in the glass itself, melted in with cobalt, copper, gold and manganese, held in a lead network and read by transmitted light. Only black trace lines are painted on; silver stain added yellows after about 1300.
Before 1400 this is effectively a four-colour system plus clear, so the figures are built from a few saturated cells and the drawing lives in the lead and the black paint. Red was a thin flashed layer on clear glass, which is why it could be scratched back to a highlight.
Lancet arcs frame a field of Voronoi panes made by clipping half-planes. Each face of the figure is split along its own surface coordinates into leaded quads, so the body reads as glass rather than paint. A slow noise cloud dims and brightens panes as if weather were passing behind the window.