Gravisim

Gravisim is a 2D gravity sandbox written in C++ using SFML. It simulates Newtonian attraction between multiple bodies and lets you fly a camera around to watch systems evolve in real time.

Highlights

• Deterministic fixed-timestep physics (120 Hz by default) for stable orbits.
• Simple n-body gravity with softening to avoid singularities.
• Per-body velocity control and orbit trails to visualize motion.
• Multiple built-in scenarios (solar system, three-body, circumbinary, many-body stress test).
• Toggleable simulation speed and pause; enable/disable trails on the fly.
• Camera based on sf::View for smooth pan/zoom without touching physics state.

Controls (default)

• Arrow keys: pan camera.
• U / D / R: speed up, slow down, reset simulation speed.
• Space: pause/resume (timescale 0/1).
• P: toggle trails (clears existing trails when toggled).
• Close window: exit.

Simulation Scenarios

• Solar System: Sun + 8 planets with roughly proportional masses and orbital radii.
• Three-Body Problem: Chaotic motion of three massive bodies.
• Circumbinary Trojans: Planet orbiting a binary system plus trojan asteroids.
• Many-Body System: Randomized positions/velocities for emergent patterns and stress testing.

Dependencies

• C++20
• SFML 2.6+

File Structure

• src/ - Source code
  • main.cpp - Entry point, scenario selection
  • sim_solarsystem.hpp, sim_threebody.hpp, sim_circumbinarytrojans.hpp, sim_lotofbody.hpp - Scenario definitions
  • core/ - Simulation engine and settings (Simulation, core_settings)
  • bodies/ - Body and manager classes, trails