workshopsoft/ludic
2
0
Fork 0
Code Issues Pull requests Projects Releases 26 Packages Wiki Activity Actions

feat(render3d): the air and the light are the hour's, not one constant apiece

Browse source 
Aerial perspective is a curve now. A low sun shines through far more air than a
high one and shines ALONG the ground rather than down onto it, so density, height
falloff and forward scatter all ride the sun's elevation; overcast thickens the air
and flattens the scatter, because a grey sky has no disc to scatter from. `lowsun`
falls away BELOW the horizon as well as above it, or the middle of the night gets a
dawn's haze with no dawn to justify it.

The term that was missing entirely is distance DESATURATION. Blending a saturated
green ridge toward a saturated blue noon sky leaves a saturated ridge - which is why
the same valley read as a photograph at dusk, where the fog colour happened to be a
warm grey, and as a toy at one o'clock. A surface is now pulled toward its own
luminance faster than the fog itself arrives. Measured far/near saturation at the
camp: 07:00 1.11 -> 0.89, 09:00 1.04 -> 0.93, 13:00 0.98 -> 0.89.

The grade is the hour's too - nine literals bound at the draw, written by
daylight_set now. Noon is the case worth naming: direct sun is warm-white and the
only thing filling a midday shadow is a blue sky, so noon gets a cool balance over a
blue-lifted shadow with hard contrast, and dawn and dusk the reverse. Ground R-B,
lit vs shadowed: 07:00 +42.8/+14.2 -> +48.9/+15.1, 13:00 +32.2/+14.8 -> +25.2/+2.9.
Gain is left alone deliberately: the grade is `c * gain + lift * (1 - c)`, so warming
it warms the whole frame, and warming it at noon made one o'clock yellower than seven
in the morning - the opposite of the point.

The visible sky is relit. Turning a photograph on its axis does not change what
colour it was taken at, so every sunset had a mid-morning blue overhead. An analytic
sky supplies the chroma and the photograph keeps the luminance: the cloud stays where
it is and goes orange at dusk, the zenith goes deep blue at noon, and no second sky
is shipped. It fades out under the horizon and eases off under cloud.

The ground bounce follows the ground, crossing meadow to rock at the map's treeline
instead of being one green constant everywhere including above the scree.

R3D_NOAIR=1 restores all of it, so a before-and-after comes from one binary at one
hour; it joins R3D_NOCLOUD / R3D_NOSHADOW / R3D_NOGI.

Verified on macOS OpenGL, macOS Vulkan (MoltenVK) and Windows Vulkan (RTX 3070 Ti).
Backends agree: mean difference 0.15-0.88/255 within a machine. Across machines the
ORIGINAL renderer already differed by 5.02/255 at 19:12 and this build differs by
2.80, so cross-platform variance is pre-existing and did not grow. 400 frames: GL
7.4 s before and after, VK 7.0 s before and after.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
This commit is contained in:
Orkun ÇAKILKAYA 2026-09-19 14:42:30 +03:00
parent f094acfdb5
commit d34fb5bc63
59 changed files with 1560 additions and 1035 deletions
Download patch file Download diff file Expand all files Collapse all files

74
packages/ludic.render3d/daylight.ludic
View file

@ -142,8 +142,80 @@ function daylight_set(hours: int) -> void {
let grey = f_add(f_mul(f_add(day_ibl[0], f_add(day_ibl[1], day_ibl[2])), fl(0.3333)), f_mul(fl(0.6), day_flash))
let dim = f_sub(F_ONE, f_mul(fl(0.55), oc))
for i in 0 .. 3 { day_ibl[i] = f_mul(f_lerp(day_ibl[i], grey, f_mul(fl(0.7), oc)), dim) }
# ---- the air ---------------------------------------------------------------------------
# Aerial perspective is a CURVE, not the one constant it was. A low sun is shining through
# far more air than a high one, and it is shining ALONG the ground rather than down onto it,
# so three things move together with its elevation: how much air there is, how hard that air
# scatters the sun forward, and how low in the valley it lies. `lowsun` peaks at the horizon
# and falls away on both sides - it has to fall away BELOW it too, or the middle of the night
# gets a dawn's haze with no dawn to justify it. Overcast thickens the air and flattens the
# scatter, because a grey sky has no disc to scatter from. The player's slider still
# multiplies the result, so nobody loses the setting they chose.
if day_fog_base == 0 { day_fog_base = r3d_fog_density }
r3d_fog_density = f_mul(f_mul(day_fog_base, day_fog_mul), r3d_fog_scale)
let fog_rise = smoothf(f_rad(fi(-12)), f_rad(fi(1)), el)
let fog_high = smoothf(f_rad(fi(2)), f_rad(fi(26)), el)
let lowsun = f_mul(fog_rise, f_sub(F_ONE, fog_high))
var dens = f_mul(day_fog_base, f_add(F_ONE, f_mul(fl(1.5), lowsun)))
dens = f_mul(dens, f_add(F_ONE, f_mul(fl(1.2), oc)))
r3d_fog_density = f_mul(f_mul(dens, day_fog_mul), r3d_fog_scale)
# how fast the haze thins with height: a settled morning's lies IN the valley, a noon sky is
# thin all the way up, so the falloff rises as the sun drops
r3d_fog_falloff = f_mul(fl(0.002), f_add(F_ONE, f_mul(fl(1.6), lowsun)))
# the glow a ridge is silhouetted against when you look into a low sun
r3d_fog_inscatter = f_mul(f_add(fl(0.012), f_mul(fl(0.16), lowsun)), f_sub(F_ONE, f_mul(fl(0.7), oc)))
# and distance takes colour away at every hour, harder under cloud
r3d_fog_desat = f_add(fl(1.9), f_mul(fl(0.6), oc))
# ---- the grade -------------------------------------------------------------------------
# The look of an hour is not only how much air is in front of the mountain; it is what colour
# the light is and what the shadows are filled with. Noon is the case worth naming: direct
# sun is warm-white and the ONLY thing filling a midday shadow is a blue sky, so a midday
# frame wants a cool, lifted shadow and a hard contrast between it and the lit ground. Dawn
# and dusk are the opposite - a warm low sun, warm shadow fill off the whole sky, and less
# contrast because the light is coming through so much air. Overcast flattens and drains both.
# `night` is deliberately NOT `1 - d`: d is already falling while the sun is still on the
# horizon, so the two curves would fight and the warmest minute of the day would come out
# half-cooled. It only begins under the horizon.
let night = f_sub(F_ONE, smoothf(f_rad(fi(-14)), f_rad(fi(-4)), el))
let hi = fog_high
post_wb_r = f_add(fl(1.02), f_sub(f_mul(fl(0.10), lowsun), f_add(f_mul(fl(0.03), hi), f_mul(fl(0.06), night))))
post_wb_g = f_add(F_ONE, f_mul(fl(0.012), lowsun))
post_wb_b = f_add(fl(0.97), f_sub(f_add(f_mul(fl(0.055), hi), f_mul(fl(0.13), night)), f_mul(fl(0.09), lowsun)))
# the shadows' floor: warm and open into a low sun, blue at noon, cold and crushed at night
post_lift_r = f_sub(f_add(fl(0.004), f_mul(fl(0.013), lowsun)), f_mul(fl(0.002), f_add(hi, night)))
post_lift_g = f_sub(f_add(fl(0.004), f_mul(fl(0.008), lowsun)), f_mul(fl(0.001), night))
post_lift_b = f_add(fl(0.012), f_add(f_mul(fl(0.004), lowsun), f_mul(fl(0.013), hi)))
# Gain is left alone on purpose. It looks like a highlight control and is not: the grade is
# `c * gain + lift * (1 - c)`, so warming the gain warms the WHOLE frame, and warming it at
# noon undid the cool white balance above and turned one o'clock yellower than seven in the
# morning - the opposite of the thing this grade exists to do. Midday's punch comes from
# contrast, and midday's colour from a cool balance over a blue shadow.
post_gain_r = fl(0.99)
post_gain_g = fl(0.995)
post_gain_b = F_ONE
post_contrast = f_sub(f_add(fl(1.12), f_mul(fl(0.11), hi)), f_add(f_mul(fl(0.17), oc), f_mul(fl(0.06), night)))
post_saturation = f_sub(f_add(fl(1.04), f_mul(fl(0.12), lowsun)), f_add(f_mul(fl(0.20), oc), f_mul(fl(0.12), night)))
# The visible sky is relit by the hour (sky.frag). It fades out under the horizon, where the
# night's own tint, stars and moon take over, and it eases off under heavy cloud - a relit
# overcast is still overcast, and driving a clear-sky model hard through one paints a blue
# zenith onto a grey day.
r3d_sky_relight = f_mul(smoothf(f_rad(fi(-10)), f_rad(fi(1)), el), f_sub(F_ONE, f_mul(fl(0.75), oc)))
# R3D_NOAIR=1: the air as it was before any of the above - one density, one falloff, the
# inscatter the shader used to hard-code, and no distance desaturation at all. It is here
# so a before-and-after can be shot from ONE binary at one hour, which is the only kind of
# comparison worth looking at, and it joins R3D_NOCLOUD / R3D_NOSHADOW / R3D_NOGI.
if r3d_env_has("R3D_NOAIR") {
r3d_fog_density = f_mul(f_mul(day_fog_base, day_fog_mul), r3d_fog_scale)
r3d_fog_falloff = fl(0.002)
r3d_fog_inscatter = fl(0.02)
r3d_fog_desat = F_ZERO
post_wb_r = fl(1.02); post_wb_g = F_ONE; post_wb_b = fl(0.97)
post_lift_r = fl(0.004); post_lift_g = fl(0.004); post_lift_b = fl(0.012)
post_gain_r = fl(0.99); post_gain_g = fl(0.995); post_gain_b = F_ONE
post_contrast = fl(1.12); post_saturation = fl(1.04)
r3d_sky_relight = F_ZERO
}
# exposure: auto-exposure must not turn the night into day
# the ceiling has to move with the moon or auto-exposure eats the difference between a
# full-moon night and a new-moon one