Two Rigid Balls (N Discs) — Switchable Collision Models

This project is a minimal 2D rigid-disc simulator with support for multiple collision handling models. Currently only the penalty model is implemented; other models are scaffolded.

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Usage

Run the main script:

python main.py

Command-line Arguments: --model : collision model to use (penalty, constraint, energy) --num : number of discs --dt : time step (seconds) --substeps : number of sub-steps per frame --e : restitution coefficient (0–1)

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Controls (Keyboard)

Arrow keys   : Apply force to selected ball (hold to apply continuously)
TAB          : Select next ball
SHIFT+TAB    : Select previous ball
m            : Cycle collision model (penalty -> constraint -> energy)
+ / -        : Add / remove a ball
g            : Toggle gravity
SPACE        : Zero velocities of all balls
r            : Reset to a random initial state
q / ESC      : Quit simulation

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Notes

• all 3 model is fully implemented in this version.

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Roadmap

• Penalty-based collision model
• Constraint-based collision model (impulse/LCP)
• Energy-based collision model (potential methods)