AC "D Tachometer" Port (IMGUI gauge HUD)

The Assetto Corsa D Tachometer v2.2 Python app (Initial D arcade gauges) ported into 7DTD as an IMGUI HUD. First done in the Supra mod (src/SupraTachometer.cs, toggle + theme gallery inside SupraPaintDialog); the recipe generalizes to any vehicle mod. Related: Assetto Corsa Import (kn5, FSB5, engine audio).

Theme pack anatomy (per theme folder themes/D3..D7)

• theme_config.ini — all layout in background-pixel coordinates; parse case-insensitively (one key is background_Pedal_height). Sections: [General] feature flags, [Background], [Gear], [RPM Gauge], [RPM Bar], [Speed], [Speed Unit], [Pedal], [Drift Light], [Rev Light].
• background/background.png + labels_{8k,9k,10k,13k,16k,18k,20k}.png — dial numbers are a separate overlay drawn at the [RPM Gauge] rect. The app picks the variant by the car's maxRpm via a top-down cascade over maxRpm_state_6..0 (falls back to the 10k dial). A 7000-rpm redline lands on labels_8k in every theme.
• rpm_bar/rpm_bar.png — the needle, drawn UNROTATED at [RPM Bar] rpm_x/y/w/h, then rotated about rpm_center_x/y by deg = rpm / (dialMax / degree_available) + degree_offset (clockwise, y-down screen space). dialMax comes from the labels variant (8k → 8000).
• gears/gear_0..10.png — 0 = R, 1 = N, 2 = 1st … 10 = 9th (AC's acsys.CS.Gear convention).
• speed_digits/speed_digits_0..9.png — digits drawn right-to-left: the ones digit sits at speed_x, each next digit at speed_x - i*(speed_width + speed_gap). D7 instead has speed_red/yellow/blue sets (variable_speed_color=True): red < 100, yellow < 150, blue ≥ 150 (thresholds on the displayed number).
• speed_unit/kmh.png|mph.png, preview.png (360×144, 2.5:1), D7 also rev_light.png: alpha 1 within 250 rpm of redline, else fades in over a 2000-rpm window ((rpm - maxRpm)/2000 + 1).
• Night variants (night_labels_*, night_rpm_bar) exist in D5-D7 — keyed to headlights in AC; unported so far.

7DTD-side notes

• IMGUI needle rotation: don't trust GUIUtility.RotateAroundPivot composition with a scaled GUI.matrix — build the matrix explicitly: `GUI.matrix = TRS(pivotScreen, Euler(0,0,deg), 1) * TRS(-pivotScreen, id, 1)
  • scaleMatrix`, draw the needle rect in virtual coords, restore. Positive z angle = clockwise in GUI space, which matches the app's math exactly.
• PNG loading needs UnityEngine.ImageConversionModule.dll referenced in the csproj (ImageConversion.LoadImage). Load once per theme, destroy the old theme's textures on switch (5 themes ≈ 5 MB of PNGs on disk).
• Gear/RPM are synthesized (7DTD vehicles have no drivetrain): signed forward speed = Vector3.Dot(ev.vehicleRB.velocity, ev.transform.forward); an 8-gear band table over top speeds picks the gear (with ~1.5 m/s downshift hysteresis), rpm lerps base→redline across the band, smoothed with Mathf.Lerp(rpm, target, 1-exp(-6*dt)). Reverse gear from negative dot.
• Settings (enabled/theme/unit) persist per save next to supra_paint.json — save-folder JSON survives redeploys, mod-folder Config/ does not.
• Theme assets ship from a mod-root folder (e.g. Tachometer/themes/); ModForge classifies them as assets drift (no restart needed), but the DLL change that renders them is restart drift.

Pushing other HUD elements out of the corner (SupraHudClearance)

The bottom-right corner is contested: vanilla HUDRightStatBars (XUi, anchor BottomRight — vehicle fuel/health, held-item bar, pickup toasts) and Uncover's IMGUI minimap. Two mechanisms, both in Supra/src/SupraHudClearance.cs:

• Generic XUi lift — the game hands you everything needed: xui.windows is a flat List<XUiV_Window>; xui.GetXUiWindowScreenBounds(view.UiTransform) returns screen-pixel (y-up) bounds of a window's sprites; xui.GetPixelRatioFactor() converts screen px → XUi units (multiply). Any visible window whose bounds overlap the reserved rect gets view.Position = basePos + (0, liftUnits); restore basePos when the overlay hides. Gotchas: compare the unshifted bounds (subtract your own applied lift) or the fix un-fixes itself next scan; windows with no UIBasicSprite children report a degenerate projected point (skip size < 2 px); skip near-fullscreen bounds (fades / vignettes); track views by reference so HUD rebuilds re-resolve; only write Position when it drifts (XUi re-parses pos on rebuild — self-healing, same trick as Uncover's HudStatBarShift).
• Cross-mod reserve handshake — never have two mods write the same window's Position (they fight at frame rate). Uncover already owns HUDRightStatBars, so Supra skips it when Uncover is loaded and instead sets Uncover.MinimapSettings.ExternalBottomReservePx (public static float, screen px measured up from the bottom edge) via reflection (Type.GetType("Uncover.MinimapSettings, Uncover"), cache the FieldInfo). Uncover adds the reserve to its minimap's bottom margin and into HudStatBarShift's target (converted px→units with GetPixelRatioFactor), stacking bars above minimap above tachometer. Any future bottom-right overlay can publish the same field.