Sawblade generator

sawblade.py

from fractions import Fraction
import math


def circle_point(angle, diameter):
    return (
        math.sin(angle * math.pi * 2) * diameter,
        math.cos(angle * math.pi * 2) * diameter,
    )


def svg_moveto(f, point):
    f.write('M' + str(point[0]) + ',' + str(point[1]) + ' ')


def svg_curve(file, point, control_point):
    f.write('Q' + str(control_point[0]) + ',' + str(control_point[1]) + ' ' + str(point[0]) + ',' + str(point[1]) + ' ')


def draw_sawblade(f, teeth, inside_diameter, outside_diameter):
    f.write('<path d="')

    for tooth in range(teeth):
        angle_start = Fraction(tooth, teeth)
        angle_end = Fraction(tooth + 1, teeth)
        angle_mid = (angle_start + angle_end) / 2
        angle_threequater = (angle_mid + angle_end) / 2

        point_start = circle_point(angle_start, inside_diameter)
        point_tip = circle_point(angle_end, outside_diameter)
        control_back = circle_point(angle_mid, outside_diameter)
        point_end = circle_point(angle_end, inside_diameter)
        control_front = circle_point(angle_threequater, (inside_diameter + outside_diameter) / 2)

        if tooth == 0:
            svg_moveto(f, point_start)

        svg_curve(f, point_tip, control_back)
        svg_curve(f, point_end, control_front)

    f.write('Z" style="stroke:#000000; fill:#CCCCCC;"/>')


with open('sawblade.svg', 'w') as f:
    f.write('<svg xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink">')

    f.write('<g id="saw">')
    draw_sawblade(f, 16, 100, 125)
    f.write('</g>')

    f.write('</svg>')