test version will be rewritten before main.

util/sim/planet.hpp

@@ -837,6 +837,57 @@ public:
 
     void addMoon() {
         ///TODO: using planetConfig, add moon(s).
+        TIME_FUNCTION;
+
+        const float realEarthRadiusKm = 6371.0f;
+        const float realMoonRadiusKm = 1737.4f;
+        const float realOrbitKm = 384400.0f;
+        float simScale = config.radius / realEarthRadiusKm;
+
+        float moonRadius = realMoonRadiusKm * simScale;
+        float orbitDistance = realOrbitKm * simScale;
+
+        std::cout << "--- MOON GENERATION ---" << std::endl;
+        std::cout << "Sim Scale: " << simScale << " units/km" << std::endl;
+        std::cout << "Moon Radius: " << moonRadius << " units" << std::endl;
+        std::cout << "Orbit Distance: " << orbitDistance << " units" << std::endl;
+
+        // Place the moon on the Z-axis to keep it distinct from the star (which is on the X-axis)
+        v3 moonCenter = config.center + v3(0.0f, 0.0f, orbitDistance);
+        v3 moonColor = v3(0.7f, 0.7f, 0.72f); // Pale gray color
+
+        // Surface area ratio Moon/Earth is ~0.074. We scale the points to maintain node density.
+        int moonPoints = std::max(1000, static_cast<int>(config.surfacePoints * 0.075f));
+
+        for (int i = 0; i < moonPoints; i++) {
+            float y = 1.0f - (i * 2.0f) / (moonPoints - 1);
+            float radiusY = std::sqrt(1.0f - y * y);
+            float Θ = Φ * i;
+            float x = std::cos(Θ) * radiusY;
+            float z = std::sin(Θ) * radiusY;
+
+            v3 dir(x, y, z);
+            v3 pos = moonCenter + dir * moonRadius;
+            Particle pt;
+            
+            pt.altPos = std::make_unique<AltPositions>();
+            pt.altPos->originalPos = pos.cast<Eigen::half>();
+            pt.altPos->noisePos = pos.cast<Eigen::half>();
+            pt.altPos->tectonicPos = pos.cast<Eigen::half>();
+            
+            pt.currentPos = pos;
+            pt.originColor = moonColor.cast<Eigen::half>();
+            pt.noiseDisplacement = 0.0f;
+            pt.surface = true;
+            
+            config.surfaceNodes.emplace_back(pt);
+            
+            grid.set(pt, pt.currentPos, true, pt.originColor.cast<float>(), config.voxelSize, true, 3, 0, 1.0, 0.0f, 0.0f, 1.0f);
+        }
+        
+        grid.optimize();
+        std::cout << "Moon generation complete. Placed " << moonPoints << " nodes." << std::endl;
+        starAdded = true;
     }
     
     void stretchPlanet() {