Our port vs the real Godot — solving the top-down glare

2026-06-28 · the actual Bonkahe SunshineClouds2 ExampleScene rendered on the real GPU (Godot 4.6, Vulkan) vs our three.js port, from the same world camera (pos 8262,30000,−10000, pitch −37.6°), top-down. This is the "match the right target" check before we change anything.

The CD's read: "Godot's clouds from top-down don't have that glaring hurtful white — surely they're doing something to solve this shadowing problem." Right instinct. We rendered the real engine to find out what — and one popular guess died on the way.

1. The guess that died: it is NOT fog

Godot's scene has aggressive depth-fog (end=40000). Natural guess: that's what hides the far glare. So we rendered Godot with fog and with fog disabled (--nofog ablation, real engine). Drag — they're identical.

◀ Godot FULL (fog on)

Godot --nofog ▶

Measured: full blown 5.5% · darks(p5) 110 · range 141 vs nofog 5.4% · 110 · 141 — fog changes nothing at this vantage. Fog hypothesis refuted. (Proving our own guess wrong is the point — the CD asked for exactly this break-it process.)

2. What Godot actually does: deep darks (not less brightness)

Drag between Godot and our port, same camera. Godot's lit tops are if anything brighter than ours (they even clip) — but it never reads as "glaring" because every crevice goes deep blue-grey. Our port is milky: same tops, but the shadows stay pale.

◀ GODOT (deep darks)

OUR PORT (milky) ▶

full-frame value structure	darks (p5)	value range	local contrast	blown
Godot (the target)	110	141	6.3	5.5%
our port (current)	136	104	4.2	0.0%

The whole difference is value depth: Godot's shadows reach 26 levels deeper and it holds ~35% more range. Same scene, same FILMIC tonemap, same sun — Godot just isn't milky. The "glaring white" was never the brightness; it's the missing darks.

3. The root: our ambient was lifting the shadows

A surgical test pinned the cause. Deeper self-shadow alone (sk16) does NOT darken the crevices (darks p5 136→135) — because the ambient light sets a floor the shadows can't sink below. Lowering the ambient (amb×0.6) is what deepens them (p5 136→107), straight toward Godot.

port setting	darks (p5)	range	local contrast
current	136	104	4.2
+ sk16 only	135	103	5.0 (darks unchanged!)
+ ambient ×0.6	107	131	5.1
+ sk16 & ambient ×0.6	106	130	6.0 ≈ Godot

4. The fix — drag to see it land on Godot

Our port with ambient ×0.6 + sk16 vs the current milky look. Same bright tops, but the crevices now carry Godot-deep darks → real dimensional form.

◀ FIX (deep darks)

current (milky) ▶

**Godot** — the reference (p5 110 · range 141)

**Our port, fixed** — amb×0.6 + sk16 (p5 106 · range 130)

Verdict

Your instinct was right — Godot solves it with shadowing, not fog or less light. The precise root: our ambient floor was lifting the crevice darks into milk. Lowering ambient (+ a touch of self-shadow) reaches Godot's value depth — bright tops untouched, 0% clipping. This is a global value-structure fix; it deepens form everywhere there's clumping.

Next: confirm this same ambient fix helps your original red merged-mass camera (it should deepen what little relief is there) + the genuinely smooth masses still want the clumping work + the grain on lit faces wants a motion check. Then two neutral teams → your eye, on a hosted build.

Method: real Godot via study-godot-sunshine/_cap.gd (+ --nofog ablation) · port matched via qa/tools/_godot-match-cap.mjs · cd-twin/tools/features.py (value structure) · this page. The fog hypothesis was rendered and refuted; the CD's eye is the verdict — this is a pre-screen.