review and remove the old euler integration code

src/bodies.cpp

@@ -99,43 +99,6 @@ void update_soi(CelestialBody* body, CelestialBody* parent, double semi_major_ax
     body->soi_radius = semi_major_axis * pow(mass_ratio, 0.4);  // 2/5 = 0.4
 }
 
-// [COMMENTED OLD CODE - Two-phase Euler update]
-// void update_simulation(SimulationState* sim) {
-//     for (int i = 0; i < sim->body_count; i++) {
-//         CelestialBody* body = &sim->bodies[i];
-//         if (body->parent_index == -1) {
-//             Vec3 total_force = {0.0, 0.0, 0.0};
-//             for (int j = 0; j < sim->body_count; j++) {
-//                 if (i == j) continue;
-//                 CelestialBody* other = &sim->bodies[j];
-//                 if (other->parent_index == -1) {
-//                     Vec3 force = calculate_gravity_force(body, other);
-//                     total_force = vec3_add(total_force, force);
-//                 }
-//             }
-//             Vec3 acceleration = calculate_acceleration(total_force, body->mass);
-//             euler_step(body, acceleration, sim->dt);
-//         }
-//     }
-//     for (int i = 0; i < sim->body_count; i++) {
-//         CelestialBody* body = &sim->bodies[i];
-//         if (body->parent_index == -1) {
-//             continue;
-//         }
-//         int new_parent = find_dominant_body(sim, i);
-//         if (new_parent != body->parent_index && new_parent != -1) {
-//             body->parent_index = new_parent;
-//         }
-//         if (body->parent_index >= 0 && body->parent_index < sim->body_count) {
-//             CelestialBody* parent = &sim->bodies[body->parent_index];
-//             Vec3 force = calculate_gravity_force(body, parent);
-//             Vec3 acceleration = calculate_acceleration(force, body->mass);
-//             euler_step(body, acceleration, sim->dt);
-//         }
-//     }
-//     sim->time += sim->dt;
-// }
-
 void update_simulation(SimulationState* sim) {
     for (int i = 0; i < sim->body_count; i++) {
         CelestialBody* body = &sim->bodies[i];

src/physics.cpp

@@ -61,17 +61,6 @@ Vec3 calculate_acceleration(Vec3 force, double mass) {
     return {0.0, 0.0, 0.0};
 }
 
-// [COMMENTED OLD CODE - Euler integration]
-// void euler_step(CelestialBody* body, Vec3 acceleration, double dt) {
-//     body->velocity = vec3_add(body->velocity, vec3_scale(acceleration, dt));
-//     body->position = vec3_add(body->position, vec3_scale(body->velocity, dt));
-// }
-
-void euler_step(CelestialBody* body, Vec3 acceleration, double dt) {
-    body->velocity = vec3_add(body->velocity, vec3_scale(acceleration, dt));
-    body->position = vec3_add(body->position, vec3_scale(body->velocity, dt));
-}
-
 Vec3 evaluate_acceleration(Vec3 pos, Vec3 vel, AccelerationContext* ctx) {
     CelestialBody temp_body = *ctx->current_body;
     temp_body.position = pos;

src/physics.h

@@ -23,7 +23,6 @@ Vec3 vec3_normalize(Vec3 v);
 // Physics functions
 Vec3 calculate_gravity_force(CelestialBody* body, CelestialBody* parent);
 Vec3 calculate_acceleration(Vec3 force, double mass);
-void euler_step(CelestialBody* body, Vec3 acceleration, double dt);
 
 // Forward declaration for RK4 context
 struct SimulationState;