Multiplication visualisation on a circle

trippy.py

#!/usr/bin/env python

import math, pygame, os, time, colorsys, sys
from pygame.locals import *
import pygame.draw, pygame.image

#constants
WINSIZE = [ 800,  800]
CENTER  = map(lambda x: x/2, WINSIZE)
RADIUS  = WINSIZE[0] / 2 - 2

def circle_point(mod, point, radius = RADIUS):
    # Return coordinate of a point on a mod circle
    angle = ((point % mod) * 360 / float(mod)) * math.pi / 180.0
    return int(CENTER[0] + radius * math.sin(angle)), int(CENTER[1] + radius * math.cos(angle))

def draw_msg(msg, coord = (5, 770), color = (180, 180, 255)):
    text = font.render(msg, True, color)
    screen.blit(text, coord)

class CircleRender:
    def __init__(self, mod, start_mult, step, hue = 0.4):
        self.mod, self.mult, self.step, self.hue = mod, start_mult, step, hue
    def draw(self, frame):
        for j in xrange(1, self.mod):
            # Draw a line between two mult points
            s = circle_point(self.mod, j)
            d = circle_point(self.mod, j * self.mult)
            hue, sat, val = self.hue + (j % 100) / 300.0, 0.5, 0.2 + j / (float(self.mod)*1.5)
            color = map(lambda x: x*255, colorsys.hsv_to_rgb(hue, 0.5, 0.2 + j / (float(self.mod)*1.5)))
            pygame.draw.line(screen, color, s, d, 1)
        self.mult += self.step

clock = pygame.time.Clock()
pygame.init()
screen = pygame.display.set_mode(WINSIZE)
font = pygame.font.SysFont(u'dejavusansmono', 12)

frame = 0
scene = CircleRender(mod = 701, start_mult = 70, step = 0.01, hue = 0.2)
while True:
    screen.fill((0, 0, 0))

    draw_msg("Up/Down:    change mult step", coord = (5, 5))
    draw_msg("Left/Right: change mod", coord = (5, 20))
    draw_msg("%04d: Mod %d, Mult %.2f (step %.3f)" % (frame, scene.mod, scene.mult, scene.step))
    scene.draw(frame)

    pygame.display.update()
    frame += 1

    for e in pygame.event.get():
        if e.type != KEYUP:
            continue
        if e.key == K_ESCAPE:
            exit(0)
        elif e.key == K_UP:
            scene.step += 0.005
        elif e.key == K_DOWN:
            scene.step -= 0.005
        elif e.key == K_LEFT:
            scene.mod -= 5
        elif e.key == K_RIGHT:
            scene.mod += 5
            
    clock.tick(25)