SpaceSim: N-Body Gravity Simulation

SpaceSim is a high-performance, real-time 2D gravity simulation built to explore the complexities of the N-body problem. Developed in C++ using modern Object-Oriented Design (OOD) principles, the project simulates thousands of celestial bodies interacting under mutual gravitational attraction at interactive speeds.

Features

• Real-Time Performance: Handles upwards of 10,000 simultaneous bodies at a stable 60+ FPS.
• Optimized Physics: Utilizes the Barnes-Hut algorithm to reduce computational complexity from $O(N^2)$ to $O(N \log N)$.
• Hardware Acceleration: Leverages OpenGL 3.3 and instanced rendering to draw thousands of entities in a single GPU call.
• Stable Integration: Employs a semi-implicit Symplectic Euler integrator and gravitational softening to ensure physical stability.
• Parallel Computing: Uses OpenMP to distribute physics calculations across multiple CPU cores.
• Cross-Platform: Built with CMake, offering standalone, zero-dependency binaries for both Linux and Windows.

Project Architecture

The system is designed with a decoupled architecture to separate physics logic from rendering:

• Universe Manager: The central orchestrator that manages the application lifecycle, boundary detection, and quadtree reconstruction.
• SimObject Hierarchy: A polymorphic base class for celestial entities (Stars, Planets) that handles physical states like position, velocity, and mass.
• Quadtree: A recursive spatial partitioning structure used to optimize force calculations.
• Renderer: A dedicated OpenGL pipeline using custom GLSL shaders for procedural "misty" galaxy aesthetics.

Tech Stack

• Language: C++20
• Graphics: OpenGL 3.3 (Core Profile), GLFW, GLAD
• Math: GLM (OpenGL Mathematics)
• UI: Dear ImGui for real-time parameter tuning
• Build System: CMake
• Parallelism: OpenMP

Implementation Highlights

The simulation solves the N-body problem numerically. Key highlights include:

• Numerical Stability: Uses gravitational softening to prevent mathematical singularities when bodies get too close.
• Procedural Aesthetics: Visuals are enhanced with fragment shaders that create radial glows and distance-based color gradients.
• Dynamic Tree Rebuilding: The Quadtree is rebuilt every frame to accommodate the moving bodies across the spatial domain.