glass.py

#!/usr/bin/env python

import math

## SETTINGS BELOW ##
# how many radiation lines to generate
DEGREE_STEP = 10
# this detemines if the glass pattern is sparse or dense
POINTS_ON_RADIATION = 20
# how much would the radiation line be twisted
TWISTING_ANGLE = 30
# radius for the circle
R = 150
# radius for drawing the dots
DOT_RADIUS = 1
# draw auxiliary lines or not?
AUX_LINES = 0

## CODE BELOW ##

size(4*R, 4*R)
translate(2*R, 2*R)
background(0.2)
stroke(0.4)
nofill()

fontsize(10)

# Reference circle
if AUX_LINES:
    oval(-R, -R, 2*R, 2*R)

real_t_ang = 90 - TWISTING_ANGLE
offset_ang = 45

for deg in range(0, 360, DEGREE_STEP):
    
    rad = math.pi * deg / 180
    end_x, end_y = math.cos(rad) * R, math.sin(rad) * R
    
    if AUX_LINES:
        stroke(0.3)
        line(0, 0, end_x, end_y)
        
    R_bar = 0.5 * R / math.cos(real_t_ang*math.pi/180)
    
    if TWISTING_ANGLE % 180 != 0:
        ctrl_x, ctrl_y = R_bar * math.cos((deg-real_t_ang)*math.pi/180),\
        R_bar * math.sin((deg-real_t_ang)*math.pi/180)

        # Draw the circle for twisted radiation
        rel_x = end_x - ctrl_x
        rel_y = end_y - ctrl_y
        if rel_x > 0 and rel_y > 0:
            end_rad = math.atan(rel_y/rel_x)
        elif rel_x > 0 and rel_y < 0:
            end_rad = math.atan(rel_y/rel_x)
        elif rel_x < 0 and rel_y > 0:
            end_rad = math.pi - abs(math.atan(rel_y/rel_x))
        else:
            end_rad = math.pi + math.atan(rel_y/rel_x)
                
        start_rad = end_rad + 2 * TWISTING_ANGLE * math.pi / 180

        stroke(0.3)
        if AUX_LINES:
            oval(ctrl_x-R_bar, ctrl_y-R_bar, R_bar*2, R_bar*2)
        
        stroke(1.0)
        for i in xrange(POINTS_ON_RADIATION):
            seed_rad = start_rad + random() * (end_rad - start_rad)
            x, y = math.cos(seed_rad) * R_bar + ctrl_x, \
                    -(math.sin(seed_rad) * R_bar + ctrl_y)
            oval(x-DOT_RADIUS, y-DOT_RADIUS, DOT_RADIUS*2, DOT_RADIUS*2)
        
    else:
        for i in xrange(POINTS_ON_RADIATION):
            seed = random()
            oval(seed*end_x-DOT_RADIUS, seed*end_y-DOT_RADIUS,
                 DOT_RADIUS*2, DOT_RADIUS*2)