Visuals

Visuals

Relativity ships an optional relativistic visual layer: what your crew would actually see near light speed. It is gameplay-decoupled — purely cosmetic, gated exactly like the physics layer (off below betaMin, under warp, and in map view, so navigation stays truthful), and the mod runs fine with it disabled or its shader bundle absent.

What you see

• Doppler colour shift — the sky ahead blueshifts, the sky behind reddens. Physically grounded: a 6500 K sky seen at Doppler factor D is a blackbody at 6500·D K, so even white stars re-colour correctly.
• Relativistic beaming — the forward sky brightens (the exact 550 nm Planck radiance ratio, ~D⁴ near D=1) and the aft sky dims toward a visibility floor. Overexposure bleeds to white the way a camera would.
• Star-bunching aberration (the "starbow") — the starfield compresses toward your direction of travel. Above β ≈ 0.5 a live rear-detail camera keeps the magnified aft sky sharp.
• Body aberration — planets, moons, and stars shift to their aberrated bearings on screen (render-only; the map, physics, and every instrument still see true positions).
• Sunflare shift — the sun's flare reddens/dims falling aft and tints blue forward, but never brightens past its stock look. With Scatterer installed the flare is captured and shifted exactly; without it a bearing-cone approximation applies.
• Doppler'd sunlight + forward headlight — hull shading follows the observed (aberrated) sun, dimming/reddening as the sun falls aft, while the beamed forward sky itself starts lighting the hull near c.
• Engine plumes stay stock colour — a separate mask keeps Waterfall/stock plumes from being tinted with the background (it only runs while engine/RCS thrust is actually flowing).

Requirements

• The pre-built shader bundle at GameData/Relativity/Shaders/relativityvisual.bundle — included in every release zip. If it is missing the visual layer silently disables (one KSP.log line) and everything else works.
• No mod dependencies. Scatterer is optional (enables exact sunflare separation); TextureReplacer skyboxes are picked up automatically.

Settings

• Difficulty Options → Relativity → Aberration sky detail — the starfield cubemap resolution (Auto measures your installed skybox, capped 4096). This governs the side sky: at high β the aberration magnifies the sky outside the rear cone too, so a low-res cube reads soft on the side faces. The aft cone itself is re-rendered live by the rear camera and stays sharp at any setting. Cube resolution costs VRAM and a one-off capture hitch, not frame rate — 4096 is the recommended fixed choice if Auto looks soft to the sides.
• relativity.cfg player keys: dopplerVisual, dopplerForceHDR, dopplerColorStrength, dopplerAberration, dopplerBodyWarp, dopplerVesselMask, dopplerSuppressScattererTAA — see Configuration#visual-layer. The full tuning surface (beam curve, floors/caps, dither…) is ModuleManager-only, with live dev sliders behind debugMode.

Anti-aliasing (read this if the ship edge shimmers)

• TUFX / PPv2 TAA is unsupported. Temporal history reprojection fights a motion-vector-less screen warp — the ship silhouette will shimmer. Use SMAA or FXAA in your TUFX profile; both are verified fine. The layer runs its own silhouette SMAA regardless.
• Scatterer's own TAA (on by default in Scatterer's settings) is suspended automatically while the visual is active and handed back after (dopplerSuppressScattererTAA).

Performance

The layer costs nothing while sub-relativistic: the HDR camera stack, the plume mask, and the rear sky camera all engage only when their conditions are met (active layer / thrust flowing / β ≥ 0.5). Measured active cost at β ≈ 0.98 (3440×1440): ≈ +1.7 ms on a light craft — vessel mask +1.25 ms, aberration +0.3 ms, rear camera +0.15 ms. The mask renders your ship a second time, so its cost grows with part count; on a very large vessel it is by far the biggest slice. If you need frames back, the levers in order: dopplerVesselMask = false, then a lower sky-detail setting (VRAM, not fps).

Troubleshooting

• No visual effect at speed — check KSP.log for the bundle-missing warning; re-install so Shaders/relativityvisual.bundle exists.
• Sky looks banded — make sure dopplerForceHDR = true (default). The dashboard's tuning foldout shows the live buffer format (src ARGBHalf · cam HDR = good).
• Ship edge sparkles/shimmers — you are almost certainly running TUFX TAA; switch to SMAA/FXAA (see above).
• Everything pink — the bundle failed to load its shader variant; re-download the release (the shipped bundle carries D3D11 + OpenGLCore).

See also

• Configuration — every key, including the visual ones.
• The Physics — the β/γ/Doppler background the visuals draw from.
• Compatibility — Scatterer, TUFX, EVE, Kopernicus multi-star notes.