Spiro - Native C Implementation of Turtle Spirograph

What is this?

This project converts the Python Turtle-based spirograph program into pure C that generates hypotrochoids and epitrochoid curves using direct mathematical calculations.

Implementation Overview

The original Python uses turtle.Turtle() which depends on the non-native Tkinter graphics backend. This C port replaces those graphics functions with parametric curve equations computed directly through standard math library:

// Parametric equations (exact from Python comments):  
double x = R * ((1.0 - k) * cos(a) 
               + l*k * cos((1.0 - k) * a / k));

double y = R * ((1.0 - k) * sin(a) 
  - l*k * sin((1.0 - k) * a / k));

// Euclidean GCD (exact purpose as Python's math.gcd()):
static unsigned long gcd(long a, long b) {
    while(b != 0) {
        long t = a % b;
        a = b;
        b = t;
    }
    return a;
}

int nRotations = (int)(r / gcd(r, R));

Build Instructions

For macOS with strict warning flags:

gcc -Wall -Wextra --std=c99 src/spiro/main.c -o pyspiro -lm
./pyspyro                          # run interactive mode
./pyspyro --sparam 150 80 0.5     # custom parameters

Git Log

$ git log --oneline 
Convert Python py codebase to C implementation (latest)  
Update README with C implementation details
Initial C port of Python spirograph

*Note: tutorial.md exists here but is NOT committed as per project requirements.

---

Credits: "Python Playground" by Mahesh Venkitachalam (electronut/pp)