forest.py

forest.py

# draws a bunch of Christmas trees
# writen by Yuhang Wang for A2PyKids
import canvas
from math import sin, cos, pi


# draws a star
def draw_star(x, y, inner_r, outer_r, jags):
  canvas.set_fill_color(1,1,0.2)
  canvas.move_to(x, y + outer_r)
  for i in xrange(jags * 2):
    angle = (2 * pi / jags) * i / 2
    if i % 2 == 0:
      r = outer_r
    else:
      r = inner_r
    a = x + r * sin(angle)
    b = y + r * cos(angle)
    canvas.add_line(a, b)
  canvas.close_path()
  canvas.set_line_width(1)
  canvas.fill_path()
  

# draws a tree rooted at point (x, y) with a star on top
def draw_tree(x, y, width, height):
  # draws the tree leaves
  canvas.set_fill_color(0,0.6,0, 0.6)
  trunk_height = height/6.5
  canvas.begin_path()
  canvas.move_to(x - width/2, y + trunk_height)
  canvas.add_line(x + width/2, y + trunk_height)
  canvas.add_line(x, y + height)
  canvas.close_path()
  canvas.fill_path()
  # draws the tree trunk
  canvas.set_line_width(width/5)
  canvas.set_stroke_color(0.5, 0.4, 0.32)
  canvas.draw_line(x, y, x, y + trunk_height)
  draw_star(x, y + height + 9, 15, 30, 5)


canvas.set_size(1000, 600)
# draws 2 rows of trees with 10 trees in each row
for x in range(10):
  draw_tree(x*100 + 50, 300, 90, 230)
  draw_tree(x*100 + 50, 40, 90, 230)