From 77830212089f4fd394e2644c0033df61ae0a2ffe Mon Sep 17 00:00:00 2001 From: cinnaboot Date: Sat, 3 Jan 2026 17:16:49 -0500 Subject: [PATCH] Convert config improvements session notes to markdown MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 🤖 Generated with Claude Code - Co-Authored-By: Claude Sonnet 4.5 --- .../2026-01-03-config-improvements.md | 206 ++++++++++++++++++ 1 file changed, 206 insertions(+) create mode 100644 docs/sessions/2026-01-03-config-improvements.md diff --git a/docs/sessions/2026-01-03-config-improvements.md b/docs/sessions/2026-01-03-config-improvements.md new file mode 100644 index 0000000..2744e91 --- /dev/null +++ b/docs/sessions/2026-01-03-config-improvements.md @@ -0,0 +1,206 @@ +# Config File Improvements & Main.cpp Refactoring + +**Date:** 2026-01-03 + +## Overview + +This session focused on refactoring main.cpp into smaller functions and adding support for eccentric orbits through an extended configuration file format. + +## Changes Made + +### 1. Main.cpp Refactoring + +Broke down 215-line main() function into focused, reusable functions: + +**New Functions:** +- `parse_command_line_args()` - Parse CLI args into ProgramArgs struct +- `print_startup_info()` - Display simulation configuration +- `run_headless_simulation()` - Terminal-based simulation with state capture +- `run_gui_simulation()` - 3D visualization mode + +**Result:** main() now only ~25 lines (setup and dispatch) + +**Additional Improvements:** +- Added initial state capture in headless mode +- Initial state now printed both at start AND end for comparison +- Cleaner separation of concerns + +### 2. Eccentric Orbit Support + +Extended config format from 10 to 12 fields: + +**Old Format (10 fields):** +``` +name mass radius x y z parent_index r g b +``` + +**New Format (12 fields):** +``` +name mass radius x y z parent_index r g b eccentricity semi_major_axis +``` + +**Implementation:** +- Uses vis-viva equation: `v = sqrt(G*M*(2/r - 1/a))` +- Circular orbits: e=0, a=orbital_radius +- Elliptical orbits: e>0, a=semi_major_axis +- Unified code path for both orbit types + +**Example Configurations:** +``` +# Circular orbit +Earth 5.972e24 6.371e6 1.496e11 0 0 0 0.0 0.5 1.0 0 1.496e11 + +# Eccentric orbit (e=0.7) +Comet 1e14 5e3 1.122e11 0 0 0 0.5 0.8 1.0 0.7 3.74e11 +``` + +### 3. Code Simplification + +- Removed dual format parsing (now single unified format) +- Shortened function name: `calculate_initial_velocities_with_params()` → `calculate_velocities()` +- Removed `OrbitParams.has_params` field (always have params now) +- Cleaner velocity calculation logic + +### 4. Testing + +Created test_simple.txt with eccentric comet: +- Eccentricity: 0.7 +- Semi-major axis: 2.5 AU +- Perihelion: 0.75 AU +- Aphelion: 4.25 AU + +**Test Results:** +- ✓ Initial velocity: 44.849 km/s (matches theoretical) +- ✓ Position varies from 0.75 AU to ~3.8 AU over simulation +- ✓ Velocity varies from 44.8 km/s (perihelion) to 10.6 km/s (aphelion) +- ✓ Energy conservation maintained + +### 5. Documentation Updates + +**README.md:** +- Updated config format section with 12-field format +- Added examples for both circular and eccentric orbits +- Added "Eccentric orbit support" to features list +- Updated field descriptions + +**docs/config_assumptions.md:** +- Documented fixed issues (eccentric orbits, main.cpp refactoring) +- Updated format assumptions (10 → 12 fields) +- Added prioritized TODO list +- Added session notes with detailed change log + +## Git Commits + +1. `e5da7aa` - Refactor main.cpp into focused functions + - Extracted argument parsing, headless sim, GUI sim + - Added initial state capture for comparison + +2. `17f11bb` - Add eccentric orbit support with unified config format + - Extended format to 12 fields + - Implemented vis-viva equation + - Added example comet configuration + +3. `8b9a06e` - Update documentation for eccentric orbit support + - Updated README with new format + - Updated config_assumptions.md + +4. `61ac1c5` - Add session notes and TODOs to config documentation + - Documented all session changes + - Created prioritized action items + +## Files Modified + +**Source Code:** +- src/main.cpp (refactored into functions) +- src/config_loader.cpp (added orbit parameters support) + +**Configuration:** +- configs/test_simple.txt (updated to 12-field format + comet) + +**Documentation:** +- README.md (new format examples) +- docs/config_assumptions.md (status updates + TODOs) + +## Known Issues & TODOs + +**HIGH PRIORITY:** +- [ ] Update configs/solar_system.txt to new 12-field format +- [ ] Update configs/example_binary_star.txt to new 12-field format +- [ ] Fix Moon position in solar_system.txt + - Current: (1.500e11, 0, 0) - 4 million km from Earth + - Should: (~1.496e11 + 3.844e8, 0, 0) - 384,400 km from Earth +- [ ] Fix Jupiter's moons positions (same issue as Moon) + +**MEDIUM PRIORITY:** +- [ ] Add config file validation +- [ ] Document coordinate system clearly (absolute vs relative) + +**LOW PRIORITY:** +- [ ] Consider relative coordinate option for child bodies +- [ ] Add 3D orbit support (currently XY plane only) + +## Technical Notes + +### Vis-Viva Equation + +``` +v = sqrt(G*M*(2/r - 1/a)) +``` + +Where: +- v = orbital velocity at current position +- G = gravitational constant +- M = parent body mass +- r = current distance from parent +- a = semi-major axis of orbit + +**For circular orbits (e=0):** +- r = a (constant) +- Equation simplifies to: `v = sqrt(G*M/r)` + +**For eccentric orbits (e>0):** +- At perihelion (r = a(1-e)): velocity is maximum +- At aphelion (r = a(1+e)): velocity is minimum +- Demonstrates Kepler's 2nd law (equal areas in equal times) + +**Orbital Period:** +``` +T = 2π * sqrt(a³/GM) +``` + +Example for comet (a=2.5 AU): T ≈ 1444 days + +## Testing Commands + +**Build:** +```bash +make +``` + +**Run with default config (currently test_simple.txt):** +```bash +./orbit_sim +``` + +**Run headless for 1000 days:** +```bash +./orbit_sim --days 1000 +``` + +**Run with specific config:** +```bash +./orbit_sim configs/test_simple.txt +``` + +**Run headless with readable units:** +```bash +./orbit_sim --headless --readable --days 365 +``` + +## Next Session Recommendations + +1. Update remaining config files to 12-field format +2. Fix moon positions with correct physics +3. Test updated configurations +4. Consider adding config validation warnings +5. Possibly add argument of periapsis parameter for 3D orbit orientation