```"""
Move a sprite in a circle.

Sample Python/Pygame Programs
Simpson College Computer Science
http://simpson.edu/computer-science/

"""

import pygame
import random
import math

# Colors
BLACK = (0, 0, 0)
WHITE = (255, 255, 255)
GREEN = (0, 255, 0)
RED = (255, 0, 0)
BLUE = (0, 0, 255)

class Block(pygame.sprite.Sprite):
""" This class represents the ball that moves in a circle. """

def __init__(self, color, width, height):
""" Constructor that create's the ball's image. """
super().__init__()
self.image = pygame.Surface([width, height])
self.image.fill(color)
self.rect = self.image.get_rect()

# The "center" the sprite will orbit
self.center_x = 0
self.center_y = 0

self.angle = 0

# How far away from the center to orbit, in pixels

# How fast to orbit, in radians per frame
self.speed = 0.05

def update(self):
""" Update the ball's position. """
# Calculate a new x, y
self.rect.x = self.radius * math.sin(self.angle) + self.center_x
self.rect.y = self.radius * math.cos(self.angle) + self.center_y

# Increase the angle in prep for the next round.
self.angle += self.speed

class Player(pygame.sprite.Sprite):
""" Class to represent the player. """
def __init__(self, color, width, height):
""" Create the player image. """
super().__init__()
self.image = pygame.Surface([width, height])
self.image.fill(color)
self.rect = self.image.get_rect()

def update(self):
"""Set the user to be where the mouse is. """
pos = pygame.mouse.get_pos()
self.rect.x = pos[0]
self.rect.y = pos[1]

# Initialize Pygame
pygame.init()

# Set the height and width of the screen
SCREEN_WIDTH = 700
SCREEN_HEIGHT = 400
screen = pygame.display.set_mode([SCREEN_WIDTH, SCREEN_HEIGHT])

# This is a list of 'sprites.' Each block in the program is
# added to this list. The list is managed by a class called 'Group.'
block_list = pygame.sprite.Group()

# This is a list of every sprite. All blocks and the player block as well.
all_sprites_list = pygame.sprite.Group()

for i in range(50):
# This represents a block
block = Block(BLACK, 20, 15)

# Set a random center location for the block to orbit
block.center_x = random.randrange(SCREEN_WIDTH)
block.center_y = random.randrange(SCREEN_HEIGHT)
# Random radius from 10 to 200
# Random start angle from 0 to 2pi
block.angle = random.random() * 2 * math.pi
block.speed = 0.008
# Add the block to the list of objects

# Create a RED player block
player = Player(RED, 20, 15)

# Loop until the user clicks the close button.
done = False

# Used to manage how fast the screen updates
clock = pygame.time.Clock()

score = 0

# -------- Main Program Loop -----------
while not done:
for event in pygame.event.get():
if event.type == pygame.QUIT:
done = True

all_sprites_list.update()

# Clear the screen
screen.fill(WHITE)

# See if the player block has collided with anything.
blocks_hit_list = pygame.sprite.spritecollide(player, block_list, True)

# Check the list of collisions.
for block in blocks_hit_list:
score += 1
print( score )

# Draw all the spites
all_sprites_list.draw(screen)

# Go ahead and update the screen with what we've drawn.
pygame.display.flip()

# Limit to 60 frames per second
clock.tick(60)

pygame.quit()

```
﻿