feat: make celestial bodies unreachable

Author: donutloop

docs/adr/0008-unreachable-celestial-bodies.md

@@ -0,0 +1,32 @@
+# 8. Unreachable Celestial Bodies
+
+Date: 2025-12-18
+
+## Status
+
+Accepted
+
+## Context
+
+In the current implementation, the sun and moon are physical meshes positioned at a radius of 800 units from the player. While this works for the visual day/night cycle, it creates issues when the player uses the airplane mode. The player can easily fly close to or even collide with the sun/moon, breaking immersion. Celestial bodies should appear infinite distance away or at least unreachable.
+
+## Decision
+
+We will simulate "infinite" distance by:
+1.  Increasing the main camera's `far` clipping plane from 1000 to 20000.
+2.  Increasing the orbital radius of the celestial bodies from 800 to 10000.
+3.  Scaling up the geometry of the celestial bodies (from radius 80 to 1000) to maintain their apparent angular size from the player's perspective.
+
+## Consequences
+
+### Positive
+- **Realism**: The sun and moon effectively become part of the skybox and cannot be reached by the player during normal gameplay.
+- **Immersion**: Maintaining the visual scale while increasing distance prevents the "toy world" feeling when flying.
+
+### Negative
+- **Z-Fighting Risk**: Increasing the far plane significantly *can* reduce depth buffer precision, potentially causing z-fighting on distant overlapping geometry. However, given our low-poly art style and the lack of complex overlapping distant geometry, this risk is minimal.
+- **Performance**: A larger frustum *might* include slightly more objects in the culling check, but our chunk system limits active objects anyway.
+
+## Compliance
+- The `WeatherSystem` class in `weather.js` will be updated to use the new larger radius and geometry size.
+- The `initScene` function in `scene.js` will be updated to use the new far plane value.

docs/adr/README.md

@@ -7,3 +7,4 @@
 *   [5. Sync Start Date with Real World](0005-sync-start-date-with-real-world.md)
 *   [6. Geometry Merging](0006-geometry-merging.md)
 *   [7. Object Pooling](0007-object-pooling.md)
+*   [8. Unreachable Celestial Bodies](0008-unreachable-celestial-bodies.md)

src/main.js

@@ -118,7 +118,7 @@ async function init() {
         verDiv.style.background = 'rgba(0,0,0,0.5)';
         verDiv.style.padding = '5px';
         verDiv.style.fontFamily = 'monospace';
-        verDiv.innerHTML = 'v6.2.0: Performance & Weather Update';
+        verDiv.innerHTML = 'v6.3.0: Unreachable Celestial Bodies';
         document.body.appendChild(verDiv);
 
         animate(() => {

src/scene.js

@@ -11,7 +11,7 @@ export function initScene() {
 
 
 
-    camera = new THREE.PerspectiveCamera(75, window.innerWidth / window.innerHeight, 0.1, 1000);
+    camera = new THREE.PerspectiveCamera(75, window.innerWidth / window.innerHeight, 0.1, 20000);
     camera.position.set(0, 5, 10);
 
     renderer = new THREE.WebGLRenderer({ antialias: true, powerPreference: "high-performance" });

src/weather.js

@@ -96,13 +96,14 @@ export class WeatherSystem {
 
     initSky() {
         // Sun
-        const sunGeom = new THREE.SphereGeometry(80, 32, 32);
+        // Increased size for distance (was 80)
+        const sunGeom = new THREE.SphereGeometry(1000, 32, 32);
         const sunMat = new THREE.MeshBasicMaterial({
             color: 0xffdd44,
             fog: false
         });
         this.sun = new THREE.Mesh(sunGeom, sunMat);
-        this.sun.position.set(50, 500, 50);
+        this.sun.position.set(500, 5000, 500);
         this.scene.add(this.sun);
     }
 
@@ -292,7 +293,7 @@ export class WeatherSystem {
         if (t >= 6 && t < 18) sunAngle = ((t - 6) / 12) * Math.PI;
         else sunAngle = ((t - 6) / 24) * Math.PI * 2;
 
-        const radius = 800;
+        const radius = 10000;
         const sunRelX = Math.cos(sunAngle) * radius;
         const sunRelY = Math.sin(sunAngle) * radius;