remove unused calculate_gravity_force function

src/physics.cpp

@@ -46,22 +46,6 @@ Vec3 vec3_normalize(Vec3 v) {
     return {0.0, 0.0, 0.0};
 }
 
-// Calculate gravitational force using Newton's law: F = G * m1 * m2 / r^2
-Vec3 calculate_gravity_force(CelestialBody* body, CelestialBody* parent) {
-    Vec3 r = vec3_sub(parent->position, body->position);
-    double distance = vec3_magnitude(r);
-
-    // Avoid division by zero
-    if (distance < 1.0) {
-        distance = 1.0;
-    }
-
-    double force_magnitude = G * body->mass * parent->mass / (distance * distance);
-    Vec3 direction = vec3_normalize(r);
-
-    return vec3_scale(direction, force_magnitude);
-}
-
 // Calculate acceleration from force: a = F / m
 Vec3 calculate_acceleration(Vec3 force, double mass) {
     if (mass > 0.0) {

src/physics.h

@@ -22,7 +22,6 @@ double vec3_distance(Vec3 a, Vec3 b);
 Vec3 vec3_normalize(Vec3 v);
 
 // Physics functions
-Vec3 calculate_gravity_force(CelestialBody* body, CelestialBody* parent);
 Vec3 calculate_acceleration(Vec3 force, double mass);
 
 // Forward declaration for RK4 context