render starmap based on HYG dataset [http://www.astronexus.com/hyg]

src/main.rs

@@ -4,6 +4,7 @@ mod world;
 mod settings;
 mod hud;
 mod actor;
+mod starchart;
 
 use bevy::window::{Window, WindowMode, PrimaryWindow, CursorGrabMode};
 use bevy::diagnostic::FrameTimeDiagnosticsPlugin;

src/world.rs

@@ -1,4 +1,4 @@
-use crate::{actor, camera};
+use crate::{actor, camera, starchart};
 use bevy::prelude::*;
 //use bevy::core_pipeline::Skybox;
 //use bevy::asset::LoadState;
@@ -10,10 +10,8 @@ use std::f32::consts::PI;
 const ASTEROID_SIZE: f32 = 100.0;
 const MOON_SIZE: f32 = 50.0;
 const MARS_SIZE: f32 = 10.0;
-const SUN_SIZE: f32 = 5000.0;
 const ASTRONAUT_SIZE: f32 = 5.0;
 
-const SUN_BRIGHTNESS: f32 = 1e5;
 //const SKYBOX_BRIGHTNESS: f32 = 300.0;
 //const SKYBOX_BRIGHTNESS_AR: f32 = 100.0;
 
@@ -31,6 +29,9 @@ impl Plugin for WorldPlugin {
     }
 }
 
+#[derive(Component)]
+pub struct Star;
+
 //#[derive(Resource)]
 //pub struct WorldState {
 //    is_loaded: bool,
@@ -140,11 +141,12 @@ pub fn setup(
         perceptual_roughness: 1.0,
         ..default()
     });
-    for i in -12..12 {
-        for j in -13..13 {
-            for k in -14..14 {
+    let maxdist = 10;
+    for i in -maxdist..maxdist {
+        for j in -maxdist..maxdist {
+            for k in -maxdist..maxdist {
                 let offset = 500.0;
-                let dist = 18000.0;
+                let dist = 3e4;
                 let wobble = dist/2.0;
                 let (i, j, k) = (i as f32, j as f32, k as f32);
                 commands.spawn((
@@ -164,21 +166,30 @@ pub fn setup(
         }
     }
 
-    // Add THE SUN
-    let hydrogenfusion_handle = materials.add(StandardMaterial {
-        emissive: Color::rgb_linear(SUN_BRIGHTNESS, 0.9 * SUN_BRIGHTNESS, SUN_BRIGHTNESS),
-        ..default()
-    });
-    commands.spawn(PbrBundle {
-        mesh: sphere_handle.clone(),
-        material: hydrogenfusion_handle.clone(),
-        transform: Transform::from_xyz(
-            0.0,
-            30000.0,
-            -500000.0,
-        ).with_scale(Vec3::splat(SUN_SIZE)),
-        ..default()
-    });
+    // Generate starmap
+    for star in starchart::STARS {
+        let brightness = star[3] * 2000.0;
+        let star_color_handle = materials.add(StandardMaterial {
+            base_color: Color::rgb(0.0, 0.0, 0.0),
+            emissive: Color::rgb_linear(brightness, 0.9 * brightness, brightness),
+            ..default()
+        });
+        let dist = 1e6;
+        commands.spawn((
+            Star,
+            PbrBundle {
+                mesh: sphere_handle.clone(),
+                material: star_color_handle.clone(),
+                transform: Transform::from_xyz(
+                        dist * star[0],
+                        dist * star[1],
+                        dist * star[2],
+                    )
+                    .with_scale(Vec3::splat((1000.0*star[3]).clamp(500.0, 2000.0))),
+                ..default()
+            }
+        ));
+    }
 
     // Add alien
     commands.spawn(SceneBundle {

tools/generate_starchart.py

@@ -0,0 +1,66 @@
+#!/usr/bin/env python
+# This script requires the following file in the current directory:
+# https://github.com/astronexus/HYG-Database/blob/cbd21013d2bb89732b893be357a6f41836dbe614/hyg/CURRENT/hygdata_v41.csv
+
+import csv
+import sys
+import math
+
+# Lower apparent magnitude = brighter.
+# Sun = -26.7
+# Sirius = -1.44
+# Betelgeuse = 0.45
+# Polaris (north star) = 1.97
+# Meissa (orion's head, 8th brightest star in orion) = 3.33
+MAX_APPARENT_MAGNITUDE = 7.0
+
+print("// This file was autogenerated by 'genrate_starchart.py' using data from")
+print("// the HYG database: https://github.com/astronexus/HYG-Database/tree/main/hyg")
+print("// License: CC BY-SA 4.0: https://creativecommons.org/licenses/by-sa/4.0/")
+print("")
+print("pub const STARS: &[[f32; 5]] = &[")
+
+
+def render(ra, dec, mag, proper):
+    ra = float(ra)
+    dec = float(dec)
+    mag = float(mag)
+
+    distance = 1.0
+    ra_radians = math.radians(ra * 15)  # ra is in [0, 24], multiplying by 15 gives degrees in [0, 360]
+    dec_radians = math.radians(dec)
+    #print(f"ra_radians={ra_radians}, dec_radians={dec_radians}, dec={dec}, ra={ra}", file=sys.stderr)
+    x = distance * math.cos(dec_radians) * math.cos(-ra_radians)
+    y = distance * math.cos(dec_radians) * math.sin(-ra_radians)
+    z = distance * math.sin(dec_radians)
+
+    # Correct for differences in coordinate system axes
+    x, y, z = x, z, y
+
+    comment = f" // {proper}" if proper else ""
+
+    brightness = 2.512 ** (0 - mag)
+
+    print(f"    [{x:.04}, {y:.04}, {z:.04}, {brightness:.04}, {ci}],{comment}")
+
+
+total = 0
+count = 0
+with open("hygdata_v41.csv", "r", encoding="utf-8") as f:
+    for entry in csv.DictReader(f):
+        total += 1
+        ra = entry['ra']
+        dec = entry['dec']
+        mag = entry['mag']
+        ci = entry['ci']
+        proper = entry['proper']
+        proper = "".join([c for c in proper if c.isalnum() or c in ' -_'])
+        if not all([ra, dec, mag, ci]):
+            continue
+        if float(mag) > MAX_APPARENT_MAGNITUDE:
+            continue
+        render(ra, dec, mag, proper)
+        count += 1
+
+print("];")
+print(f"Wrote {count} stars (total={total}).", file=sys.stderr)