AuraLite Shaders

🆕 What's New in v1.1.0 — True Volumetric Godrays, HDR Pipeline & Experimental Physical Sky

Version 1.1.0 replaces the screen-space godray approximation with a fully volumetric raymarched implementation, switches the entire G-buffer pipeline to true HDR (RGBA16F), and introduces an experimental, fully physical realtime atmospheric-scattering sky mode as an opt-in alternative to the stable gradient sky. This is a focused two-pillar update on top of the v1.0.7 bug-fix baseline.

🌤️ True Volumetric Godrays

The old computeGodrays() screen-space approximation has been replaced by computeVolumetricGodrays() — a genuine single-scattering volumetric raymarch:

• Per-step shadow-map occlusion — every raymarch sample now tests the shadow map individually, so light shafts are actually carved by real geometry (trees, buildings, cave ceilings) instead of being implied by a "forward-looking boost" toward the sun.
• Interleaved Gradient Noise dithering (Jimenez 2014), rotated per-frame via the new frameCounter uniform when TAA is active — 8–24 raymarch steps now integrate as smoothly as hundreds, with no banding.
• Exact per-segment Beer–Lambert integration — Tr₀ · σs/σt · (1 − e^(−σt·Δx)) per step, which is energy-conserving regardless of step size (no more over-brightening at low sample counts).
• Dual-lobe Henyey-Greenstein phase function (forward + weak backscatter lobe) with an isotropic floor, so crepuscular rays stay visible when looking across them, not only when staring directly at the sun.
• Colored radiance — shafts are now warm Kelvin-driven sunbeams by day, deep orange at sunset, and faint blue moonbeams at night, instead of a flat white/yellow overlay.
• New GODRAYS_STRENGTH setting (Subtle / Balanced / Dramatic) added to every quality profile.
• GODRAYS_QUALITY sample counts and distances increased: Fast 8 samples/96m, Balanced 16/128m, High 24/160m (up from 4/72m, 6/110m, 8/150m in v1.0.7).

✨ Full HDR G-Buffer Pipeline

• colortex0, colortex1, and colortex2 are now explicitly RGBA16F. Bright sources — the sun disk, lava, specular highlights, portals — no longer clip to 1.0 before tone mapping, so the ACES/AgX curves in final.fsh finally compress genuine HDR highlights instead of receiving pre-clamped input. Bloom now samples real HDR luminance rather than an already-saturated LDR buffer.
• colortex2's alpha channel carries a 5-value material tag (0.0/0.1/0.62/0.8/1.0); RGBA16F guarantees these are preserved exactly, whereas a lower-precision format would have aliased and collided material tags (e.g. foliage vs. water).
• Godray intensity constants were re-tuned (roughly halved vs. the old LDR values) now that the additive shaft survives in full instead of clipping against a saturated scene; a stronger soft shoulder (0.50 vs. the old 0.30) keeps the sun-facing core from blowing out under HDR.

🧪 Experimental: Realtime Physical Sky (Off by Default)

A brand-new [EXPERIMENTAL] menu tab exposes an alternate sky renderer in gbuffers_skybasic.fsh, disabled in every shipped profile (SKY_MODE=0) so the stable gradient sky remains the default:

• SKY_MODE — 0 (Gradient, legacy v1.0.7-style sky) or 1 (Physical Realtime): a genuine per-pixel ray-marched atmosphere with exact 1st-order single scattering (Rayleigh + Mie + Ozone, full sun-ray optical-depth march with ground-occlusion detection) plus a blue-biased, bounded multiple-scattering ambient term that fills in the zenith/horizon without producing the typical LUT-based "yellow band" artifact. No lookup textures, no cross-frame reads.
• SKY_QUALITY — controls raymarch sample counts (Fast 8×4 / Standard 12×6 / High 16×8) for the physical mode.
• SKY_STYLE — new artistic-direction toggle independent of SKY_MODE: Realistic (true angular sun/moon size, neutral colors, minimal glow — an authentic astronomy look), Semi-realistic (readable ×2.8 sun/moon size, richer color, soft aureole — the default), or Fantasy (grand ×5.5 sun/moon, huge corona, vivid saturated teal/crimson/indigo palette for a stylized sky).
• Physical mode renders the sun disk with real limb darkening and a physically-derived angular radius, and computes its color from actual sun-ray transmittance (ozone-aware) rather than the legacy Kelvin/airmass approximation.
• Because this feature is explicitly experimental and disabled by default, it introduces no behavioral change to any existing profile.

🛠️ Smaller Fixes & Cleanup

• Dark-sky/moon-halo banding fixed at the source — a linear-space triangle-distributed dither (±1/255, matching the BSL/Complementary technique) is now applied in final.fsh before tone mapping, where gamma expansion makes a tiny linear noise term large enough in the darks to smooth the gradient, while staying invisible in bright regions. The old post-gamma dither (which couldn't fix pre-tonemap banding) has been removed and replaced with an explicit final clamp().
• shadow.vsh no longer relies on the deprecated fixed-function ftransform(); it now builds the clip-space position explicitly via gl_ModelViewMatrix / gl_ProjectionMatrix for broader driver compatibility.
• Updated localization strings for GODRAYS, GODRAYS_QUALITY, and the new GODRAYS_STRENGTH / SKY_MODE / SKY_STYLE / SKY_QUALITY options and the new Experimental tab.