ReadStar

# ReadStar — NeoForge Astronomy Mod !(https://cdn.modrinth.com/data/cached_images/2af8e0a314076124c824884df31c5ea5a25edc68_0.webp) A Minecraft sky mod driven by real celestial mechanics and star catalog data, featuring planetary orbital systems, star catalogs, FOV-aware rendering, and server-synchronized celestial configuration. **Author**: FrozenStream ## Features - **Real Star Catalog** — 12,000+ real stars from Gaia DR3 (color) + BSC5 (bright star fallback), with per-star brightness and glow - **Real Celestial Mechanics** — Keplerian orbital system with unlimited nesting depth - **Atmospheric Scattering** — HSV-based atmosphere color & glow computation with full-sky overlay and stellar halo - **Comet Rendering** — Bézier dust + ion dual-tail structure with dynamic wobble - **FOV-Aware Rendering** — Custom shader keeps star screen size constant across FOV changes - **Zero-Code Customization** — Add 8 moon phases to any body by simply placing PNGs - **Server Sync** — Celestial config managed server-side, auto-synced to all clients --- ## Quick Start ```bash ./gradlew build # Build ./gradlew runClient # Run client ./gradlew runData # Data generation (atlas config) ./gradlew runServer # Run server ``` The celestial system is defined via **data pack** at `data/readstar/celestial/system.json`, and the star catalog via **resource pack** at `assets/readstar/custom/stars/stars.json`. Config changes take effect with F3+T. Data pack changes require `/reload` or restart. --- ## Configuration Config file: `run/config/readstar-common.toml` | Option | Default | Description | |--------|---------|-------------| | `starCoreSize` | `0.648` | Star core quad size multiplier | | `starGlowSize` | `1.5` | Bright star glow quad size multiplier | | `starFovCompensationStrength` | `0.8` | Star **size** FOV compensation. `1.0` = full, `0.0` = none | | `starFovBrightnessStrength` | `1.0` | Star **brightness** boost when zoomed in. `0.0` = none | | `celestialApparentSizeFactor` | `4000.0` | Celestial body apparent size factor | | `celestialApparentSizeMin` | `1.024` | Minimum apparent size clamp | ### FOV-Aware Rendering Stars use a custom shader that separates each point into **position** and **offset**: | Attribute | Meaning | Behavior | |-----------|---------|----------| | `Position` (vec3) | Celestial sphere coordinate, shared by 4 vertices | Transformed by MVP, naturally affected by FOV | | `Offset` (vec3) | Billboard corner offset, unique per vertex | Multiplied by `FovCompensation` for size correction | Formula: `FovCompensation = tan(fov/2) / tan(35°) × strength + (1 - strength)` Shader: `worldPos = Position + Offset × FovCompensation` ### Per-Star Brightness Based on Vmag with independent decay thresholds: | Parameter | Formula | Notes | |-----------|---------|-------| | Alpha | `clamp(1 - max(0, Vmag-3)/12, 0.4, 1)` | Full brightness at Vmag ≤ 3 | | RGB | `clamp(1 - max(0, Vmag-1)/19, 0.7, 1)` | Full brightness at Vmag ≤ 1 | | Size | `clamp(1 - Vmag/12, 0.5, 1) × starCoreSize` | Larger Vmag = smaller dot | Glow quads only for Vmag < 2.0: `< 0.5 → high / < 1.5 → medium / < 2.0 → low`. --- ## Data Pack — Celestial System **Path**: `data/readstar/celestial/system.json` Place at `saves/<world>/datapacks/<pack>/data/readstar/celestial/system.json` or server `world/datapacks/`. ### Structure ```json { "System": { "<name>": { "mass": <double>, "radius": <double>, "luminance": <int>, "unstableDirtySnowball": <bool>, "hasAtmosphere": <bool>, "atmosphereHSV": <int>, "starHSV": <int>, "axis": , "orbit": { "semiMajorAxis": <double>, "eccentricity": <double>, "inclination": <double>, "argumentOfPeriapsis": <double>, "longitudeOfAscendingNode": <double>, "initialMeanAnomaly": <double> }, "children": { "<name>": { ... } } } } } ``` ### Field Reference | Field | Description | |-------|-------------| | `mass` | Mass (kg). 0 = fixed at parent position | | `radius` | Radius (m). Apparent size = `max(1.024, radius / distance × factor)` | | `luminance` | Self-luminosity 0~15. >0 = star; children auto-resolve `hostStar` upward | | `unstableDirtySnowball` | Comet flag. `true` renders dual-tail structure | | `hasAtmosphere` | Has atmosphere (controls overlay and glow rendering) | | `atmosphereHSV` | Atmosphere HSV color, packed int (H<<16 \| S<<8 \| V). H=hue, S=saturation, V=density (0~255) | | `starHSV` | Body's own color, same encoding. Luminous = emission, non-luminous = surface reflection | | `axis` | Rotation axis. Zero vector defaults to `(0,0,-1)` | | `orbit.semiMajorAxis` | Semi-major axis (m). 0 = no orbit | | `orbit.eccentricity` | Eccentricity. 0 = circular | | `orbit.inclination` | Orbital inclination (radians) | | `orbit.argumentOfPeriapsis` | Argument of periapsis (radians) | | `orbit.longitudeOfAscendingNode` | Longitude of ascend