Which way the year is going: 1 at mid-spring, 0 at mid-autumn, 0.5 at both
solstices.
SeasonState.winter says how cold it is; this says whether the cold is
arriving or leaving — and that is the whole difference between spring and
autumn, which pass through identical temperatures in opposite directions. The
foliage tint needs it to know whether a half-cooled leaf should be fresh green
or gold (see FOLIAGE_GLSL).
It's a sine rather than a step so nothing pops at the solstices — and the
crossover lands exactly where the mid-season color has the least influence,
because at midsummer and midwinter the foliage is at one end of its range
anyway.
Which way the year is going: 1 at mid-spring, 0 at mid-autumn, 0.5 at both solstices.
SeasonState.winter says how cold it is; this says whether the cold is arriving or leaving — and that is the whole difference between spring and autumn, which pass through identical temperatures in opposite directions. The foliage tint needs it to know whether a half-cooled leaf should be fresh green or gold (see
FOLIAGE_GLSL).It's a sine rather than a step so nothing pops at the solstices — and the crossover lands exactly where the mid-season color has the least influence, because at midsummer and midwinter the foliage is at one end of its range anyway.