grid_major 0x2A3038 -> 0x39414C, still well under axis_line's 0x8A94A6, so the three-way
hierarchy the eye reads stays minor < major < axis. Already fully opaque, so "more
prominent" meant a brighter colour and nothing else.
The tests that classify grid pixels take their colours from the style, so they followed
the change; the one hardcoded mention (grid_pixel()'s doc comment) is updated, and the
minor's relationship to the major is now stated as an order of magnitude rather than the
fifth the old colours happened to give. 361 cases, 0 failed.
Subdivisions used to be drawn exactly like the labelled lines -- same width, same
opacity -- so a plot dense enough to need them read as two competing sets of ticks.
The minor class is now three things the style states explicitly:
- grid_minor_width 1.0 -> 0.75, a sub-pixel logical width. At 1x that is expressed as
reduced coverage through the anti-aliased ramp; on a HiDPI display the line is
literally narrower.
- grid_minor_dash_on/_off (new, 3/3): dashed by default, off == 0 draws it solid, the
same convention as the crosshair's and a trace's dash. The dash is a fragment-shader
discard, so no geometry is added -- the vertices are the line either way.
- grid_minor carries alpha (0x1C2126 at 50%), and the line shader applies u_color.a,
so it blends into the background instead of sitting on it.
Together that is about a fifth of the ink a major line leaves along its length, which
is what gives the eye one grid to read instead of two. The major class is untouched:
it stays the structure.
Tests: a new pixel test (the_minor_grid_is_thinner_dashed_and_dimmer_than_the_major)
asserts a major column is inked top-to-bottom while a minor one alternates, and that
the minor's ink sits closer to the background than the major's. Three existing tests
counted the minor class as "most of eight rows" of its exact colour; two now take
their floor from the style (minor_line_ink: width x alpha x duty), and the width test
states the dash and alpha away because widths are its subject. 361 cases, 0 failed.
Martino Ferrari