fix(sky): apply per-Surface Translucency + Luminosity for retail-faithful weather
Two independent brightness bugs were compounding to make rain ~6.7×
too bright at the cylinder rim, and clouds full-bright instead of
time-of-day-tinted:
**Fix 1 — Surface.Translucency was never plumbed to the shader.**
Retail's D3DPolyRender::SetSurface at 0x59c767: when the Surface's
Translucent (0x10) bit is set, its translucency float drives per-vertex
alpha (curr_alpha = ftol(0.5 × 255) = 127). ACViewer
(TextureCache.cs:142) and WorldBuilder (ObjectMeshManager.cs:1115) both
encode the same as `opacity = (1 - x)`. acdream read only Surface.Type
and Surface.Luminosity in GfxObjMesh.Build() — Surface.Translucency
(the float) was never read, never stored, never reached the shader.
For the rain Surface 0x080000C5 (Translucency=0.5) this meant rain
streaks were at full alpha=1.0 instead of 0.5 — 2× brighter than retail
under the (SrcAlpha, One) blend.
Plumbed end-to-end:
GfxObjSubMesh.SurfTranslucency (init float, default 0)
GfxObjMesh.Build() reads surface.Translucency next to .Luminosity
SubMeshGpu.SurfTranslucency carries it to draw time
SkyRenderer.RenderPass writes uniform `uSurfTranslucency`
sky.frag final alpha: a = sampled.a × (1 - uTransparency) ×
(1 - uSurfTranslucency)
Bonus reach: cloud surface 0x08000023 has Translucency=0.25 → clouds
also dimmed by 25%, more retail-faithful overall.
**Fix 2 — Emissive default was 1.0 instead of the surface's actual Luminosity.**
The sky shader's `effEmissive = (luminosity > 0) ? luminosity : sub.SurfLuminosity`
fallback never fired because the local `luminosity` defaulted to 1f (always
> 0). Every sky mesh got effEmissive=1.0, saturating vTint to white before
the alpha blend. The comment claimed the fallback was active; the code
disagreed.
Empirical sky-surface LUMINOUS audit (RainMeshProbe a6e7108) found that
NO Dereth sky surface carries the SurfaceType.Luminous flag (0x40) —
the previous code comment that did was wrong. The differentiator is
purely the Surface.Luminosity FLOAT:
dome/sun/moon: Lum=1.0 → vTint saturates → texture passthrough
stars/clouds: Lum=0.0 → vTint = ambient + sun·N·L → time-of-day tint
rain: Lum=0.1484 → faint emissive baseline + lit additions
Refactored:
replaceLuminosity = NaN sentinel for "no replace override"
rep.Luminosity > 0 → set replaceLuminosity to override value
rep.MaxBright > 0 → cap replaceLuminosity at MaxBright
effEmissive = NaN ? sub.SurfLuminosity : replaceLuminosity
Dead uniform `uLuminosity` removed from sky.frag and SkyRenderer SetFloat
call — the redundant multiply was already commented-out earlier this
year (would have double-dimmed clouds), and the uniform value was unused
in the fragment.
Visual verification (Holtburg, live ACE, Rainy DG forced and natural
LCG-picked): rain rim is no longer visible; cloud direction matches
retail when the same DayGroup is active; sky lighting transitions through
day cycle with appropriate time-of-day tint on stars/clouds.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
This commit is contained in:
Erik
parent
a6e7108122
commit
4678b3ee6b
4 changed files with 127 additions and 33 deletions
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@ -2,17 +2,16 @@
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// Sky mesh fragment shader — final composite matching retail's
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// D3D fixed-function:
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//
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// fragment.rgb = texture.rgb × vTint × uLuminosity + lightning_flash
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// fragment.a = texture.a × (1 - uTransparency)
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// fragment.rgb = texture.rgb × vTint + lightning_flash
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// fragment.a = texture.a × (1 - uTransparency) × (1 - uSurfTranslucency)
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//
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// vTint arrives from the vertex shader with retail's per-vertex
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// lighting formula baked in (Emissive + lightAmbient + lightDiffuse ×
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// max(N·L, 0)) — see sky.vert for the decompile citation.
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//
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// uLuminosity is the per-keyframe SkyObjectReplace.Luminosity override
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// (0..1, /100 in SkyDescLoader). It's a SEPARATE field from the
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// Surface.Luminosity that feeds uEmissive in the vertex shader — they
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// compose multiplicatively in retail too.
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// max(N·L, 0)) — see sky.vert for the decompile citation. The keyframe
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// SkyObjectReplace.Luminosity override is folded into uEmissive on the
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// CPU side (SkyRenderer.cs) so vTint already saturates properly for
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// bright keyframes; the previous shader had a redundant uLuminosity
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// multiply that was double-dimming clouds, removed 2026-04-26.
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//
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// See `docs/research/2026-04-23-sky-material-state.md`.
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@ -22,8 +21,15 @@ in float vFogFactor; // 1 = no fog (near), 0 = full fog color (far)
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out vec4 fragColor;
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uniform sampler2D uDiffuse;
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uniform float uTransparency; // 0 = fully visible, 1 = fully transparent
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uniform float uLuminosity; // SkyObjectReplace.Luminosity override (0..1)
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uniform float uTransparency; // 0 = fully visible, 1 = fully transparent
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// Surface.Translucency float (0..1) — distinct from uTransparency
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// (which is the per-keyframe Replace override). Retail
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// D3DPolyRender::SetSurface at 0x59c767 reads this when the Surface's
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// Translucent (0x10) bit is set and converts to per-vertex alpha;
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// ACViewer + WorldBuilder both apply opacity = (1 - x). Both factors
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// compose multiplicatively into final fragment alpha. For non-Translucent
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// surfaces uSurfTranslucency = 0 ⇒ no effect.
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uniform float uSurfTranslucency;
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// Shared SceneLighting UBO — fog params drive the mix, flash channel
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// bumps sky brightness during lightning strikes. Matches sky.vert's
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@ -45,14 +51,13 @@ layout(std140, binding = 1) uniform SceneLighting {
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void main() {
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vec4 sampled = texture(uDiffuse, vTex);
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// Composite: texture × per-vertex lit.
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// `rep.Luminosity` is now pushed into `uEmissive` on the CPU side
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// (SkyRenderer.cs) so `vTint` already saturates properly for bright
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// keyframes. Multiplying by uLuminosity again here would dim the
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// result — a BUG that was making clouds render as grey instead of
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// white. Retail's fragment formula (FUN_0059da60 non-luminous
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// branch) is texture × litColor × vertex.color(=white), so just
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// `texture × vTint` is the retail-faithful composite.
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// Composite: texture × per-vertex lit. Replace.Luminosity (per
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// keyframe) and Surface.Luminosity are both folded into uEmissive
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// on the CPU side (SkyRenderer.cs) so vTint already carries the
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// right tint for the time-of-day. Retail's fragment formula
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// (FUN_0059da60 non-luminous branch) is texture × litColor ×
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// vertex.color(=white), so `texture × vTint` is the retail-faithful
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// composite.
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vec3 rgb = sampled.rgb * vTint;
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// Retail vertex fog: lerp(fogColor, scene, fogFactor). DISABLED
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@ -79,7 +84,14 @@ void main() {
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float cap = mix(1.0, 3.0, clamp(flash, 0.0, 1.0));
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rgb = min(rgb, vec3(cap));
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float a = sampled.a * (1.0 - uTransparency);
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// Final fragment alpha = texture-alpha × keyframe-replace-opacity
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// × surface-translucency-opacity. Both opacity factors are
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// (1 - x) form per ACViewer (TextureCache.cs:142) and WorldBuilder
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// (ObjectMeshManager.cs:1115). For the rain mesh 0x01004C42/0x01004C44:
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// sampled.a = 1.0 (R8G8B8 texture), uTransparency = 0,
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// uSurfTranslucency = 0.5 → a = 0.5 → with the (SrcAlpha, One) blend
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// the streak contribution is halved, matching retail's curr_alpha = 127.
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float a = sampled.a * (1.0 - uTransparency) * (1.0 - uSurfTranslucency);
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if (a < 0.01) discard;
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fragColor = vec4(rgb, a);
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}
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@ -211,14 +211,31 @@ public sealed unsafe class SkyRenderer : IDisposable
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uint gfxObjId = obj.GfxObjId;
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float headingDeg = 0f;
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float transparent = 0f;
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float luminosity = 1f;
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// Replace-override luminosity. Stays NaN when there is no
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// replace entry or none of the keyframe's overrides are set,
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// and that NaN is the signal to fall back to the surface's
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// authored Luminosity at draw time. This replaces the previous
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// `luminosity = 1f` default which masked the surface value
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// because the `(luminosity > 0) ? luminosity : sub.SurfLuminosity`
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// fallback at the inner loop never fired (1f is always > 0).
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// RainMeshProbe (committed b8e0857) confirmed empirically that
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// NO Dereth sky surface carries the SurfaceType.Luminous flag
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// bit (0x40) — the differentiator is purely the float field.
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float replaceLuminosity = float.NaN;
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if (replaces.TryGetValue((uint)i, out var rep))
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{
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if (rep.GfxObjId != 0) gfxObjId = rep.GfxObjId;
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if (rep.Rotate != 0f) headingDeg = rep.Rotate;
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transparent = Math.Clamp(rep.Transparent, 0f, 1f);
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if (rep.Luminosity > 0f) luminosity = rep.Luminosity;
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if (rep.MaxBright > 0f) luminosity = MathF.Min(luminosity, rep.MaxBright);
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if (rep.Luminosity > 0f) replaceLuminosity = rep.Luminosity;
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// MaxBright is a CAP: even if the surface authored Lum=1.0,
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// a per-keyframe MaxBright trims it. When no explicit
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// Luminosity replace exists, MaxBright still acts as the
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// ceiling (applied against sub.SurfLuminosity at draw time).
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if (rep.MaxBright > 0f)
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replaceLuminosity = float.IsNaN(replaceLuminosity)
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? rep.MaxBright
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: MathF.Min(replaceLuminosity, rep.MaxBright);
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}
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if (gfxObjId == 0) continue;
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@ -262,7 +279,6 @@ public sealed unsafe class SkyRenderer : IDisposable
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float vOffset = (obj.TexVelocityY * secondsSinceStart) % 1f;
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_shader.SetVec2("uUvScroll", new Vector2(uOffset, vOffset));
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_shader.SetFloat("uTransparency", transparent);
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_shader.SetFloat("uLuminosity", luminosity);
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EnsureMeshUploaded(gfxObjId);
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if (!_gpuByGfxObj.TryGetValue(gfxObjId, out var subMeshes)) continue;
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@ -281,19 +297,44 @@ public sealed unsafe class SkyRenderer : IDisposable
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else
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_gl.BlendFunc(BlendingFactor.SrcAlpha, BlendingFactor.OneMinusSrcAlpha);
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// Emissive source: retail's FUN_0059da60 for non-luminous
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// surfaces writes rep.Luminosity into D3DMATERIAL9.Emissive
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// (via material cache +0x3c). This PROMOTES bright-keyframe
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// clouds into the self-lit term so the litColor saturates
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// and the texture renders at full brightness rather than
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// being dimmed by a per-fragment multiply.
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// Emissive source picks the surface's authored Luminosity by
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// default; the per-keyframe replace data can OVERRIDE
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// (rep.Luminosity > 0) or CAP (rep.MaxBright). This matches
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// retail's FUN_0059da60: surface.Luminosity → D3DMATERIAL.Emissive
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// (via material cache +0x3c), with the keyframe replace
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// promoting bright-keyframe clouds when the keyframe asks.
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//
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// If no rep.Luminosity override: fall back to the Surface's
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// static Luminosity (1.0 for dome/sun/moon → saturates;
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// 0.0 for stars → stays ambient-lit, correct retail look).
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float effEmissive = (luminosity > 0f) ? luminosity : sub.SurfLuminosity;
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// Empirical Dereth sky surfaces (RainMeshProbe, b8e0857):
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// dome/sun/moon → Lum=1.0 → vTint saturates → texture
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// passthrough (correct retail look);
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// stars/clouds → Lum=0.0 → vTint = ambient + diffuse →
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// picks up the time-of-day tint;
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// rain → Lum=0.1484 → faint emissive baseline,
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// ambient+diffuse adds atmospheric tint.
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//
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// Pre-fix: the replace-override variable defaulted to 1f and
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// the fallback `(luminosity > 0) ? luminosity : sub.SurfLuminosity`
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// never fired — every sky mesh got effEmissive=1.0,
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// saturating vTint. That made stars/clouds look full-bright
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// instead of time-of-day-tinted, and made rain streaks
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// 6.7× too bright (one of two factors compounding the
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// foreground-rim visibility bug).
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float effEmissive = float.IsNaN(replaceLuminosity)
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? sub.SurfLuminosity
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: replaceLuminosity;
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_shader.SetFloat("uEmissive", effEmissive);
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// Retail per-Surface translucency override (D3DPolyRender::SetSurface
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// at 0x59c767): when the Surface's Translucent (0x10) bit is set,
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// its translucency float drives per-vertex alpha. Both ACViewer
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// and WorldBuilder render this as opacity = (1 - x). The shader
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// multiplies output alpha by (1 - uSurfTranslucency); for surfaces
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// without the bit, SurfTranslucency=0 ⇒ no effect. Critical for
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// the rain mesh 0x01004C42/0x01004C44 (Translucency=0.5) so its
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// streaks contribute at half intensity instead of full under the
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// additive (SrcAlpha, One) blend.
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_shader.SetFloat("uSurfTranslucency", sub.SurfTranslucency);
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uint tex = _textures.GetOrUpload(sub.SurfaceId);
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_gl.ActiveTexture(TextureUnit.Texture0);
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_gl.BindTexture(TextureTarget.Texture2D, tex);
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@ -514,6 +555,7 @@ public sealed unsafe class SkyRenderer : IDisposable
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IsAdditive = isAdditive,
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SurfLuminosity = sm.Luminosity,
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NeedsUvRepeat = sm.NeedsUvRepeat,
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SurfTranslucency = sm.SurfTranslucency,
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};
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}
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@ -563,5 +605,16 @@ public sealed unsafe class SkyRenderer : IDisposable
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/// Computed once at mesh build from the actual UV range.
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/// </summary>
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public bool NeedsUvRepeat;
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/// <summary>
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/// <c>Surface.Translucency</c> float (0..1) carried through from
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/// <see cref="GfxObjSubMesh.SurfTranslucency"/>. Passed to the
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/// sky fragment shader as <c>uSurfTranslucency</c>; the shader
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/// multiplies output alpha by <c>(1 - x)</c>. For the rain
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/// surface 0x080000C5 this is 0.5 → opacity 0.5 → rain streaks
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/// contribute at half intensity under the additive blend, matching
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/// retail's <c>curr_alpha</c> derivation in
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/// <c>D3DPolyRender::SetSurface</c> at <c>0x59c767</c>.
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/// </summary>
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public float SurfTranslucency;
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}
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}
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@ -200,6 +200,7 @@ public static class GfxObjMesh
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// docs/research/2026-04-23-sky-retail-verbatim.md §6).
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var translucency = TranslucencyKind.Opaque;
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var luminosity = 0f;
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var surfTranslucency = 0f;
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if (dats is not null)
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{
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var surface = dats.Get<Surface>(surfaceId);
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@ -207,6 +208,15 @@ public static class GfxObjMesh
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{
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translucency = TranslucencyKindExtensions.FromSurfaceType(surface.Type);
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luminosity = surface.Luminosity;
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// Retail D3DPolyRender::SetSurface at 0x59c767: when the
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// Translucent (0x10) flag is set, the surface's
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// Translucency float drives per-vertex alpha. Both
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// ACViewer and WorldBuilder apply opacity = (1 - x).
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// For the rain Surface 0x080000C5 this is 0.5. Carrying
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// the float verbatim and converting to opacity in the
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// shader keeps non-Translucent surfaces (Translucency=0)
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// identical to the previous behavior.
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surfTranslucency = surface.Translucency;
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}
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}
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@ -235,6 +245,7 @@ public static class GfxObjMesh
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Translucency = translucency,
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Luminosity = luminosity,
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NeedsUvRepeat = needsUvRepeat,
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SurfTranslucency = surfTranslucency,
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});
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}
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return result;
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@ -53,4 +53,22 @@ public sealed record GfxObjSubMesh(
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/// Defaults to false so non-sky consumers get the previous behavior.
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/// </summary>
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public bool NeedsUvRepeat { get; init; } = false;
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/// <summary>
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/// <c>Surface.Translucency</c> float (0..1 — distinct from the
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/// <see cref="TranslucencyKind"/> classifier above, which buckets the
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/// flag bits). Retail's <c>D3DPolyRender::SetSurface</c> at
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/// <c>0x59c767</c> reads this when the <c>Translucent</c> (0x10) bit
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/// is set on the surface and feeds it into the per-vertex alpha
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/// (<c>curr_alpha</c>); the rasterizer then multiplies fragment alpha
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/// by <c>(1 - translucency)</c> so the resulting opacity is
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/// <c>1 - x</c>. ACViewer (<c>TextureCache.cs:142</c>) and WorldBuilder
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/// (<c>ObjectMeshManager.cs:1115</c>) both use the same convention.
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/// For the rain Surface 0x080000C5, <c>Translucency = 0.5</c> ⇒
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/// opacity = 0.5; with the <c>(SrcAlpha, One)</c> additive blend the
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/// rain streaks contribute at half intensity instead of full.
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/// Defaults to 0.0 (fully opaque) so non-translucent surfaces render
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/// through the normal lighting path without change.
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/// </summary>
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public float SurfTranslucency { get; init; } = 0f;
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}
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