蓝天排松鸟飞图_带装饰器的绘画

"""蓝天排松鸟飞图_演示arcade装饰器的用法。
这是画一幅很多鸟在蓝天上飞的动画。蓝天下面是两排松树。
"""

# 导入模块
import arcade
import random

SCREEN_WIDTH = 800
SCREEN_HEIGHT = 600


def draw_background(window):
    """
    本函数画地面和蓝天
    """
    # 在屏幕三分之二的上面区域画蓝天
    arcade.draw_rectangle_filled(SCREEN_WIDTH / 2, SCREEN_HEIGHT * 2 / 3,
                                 SCREEN_WIDTH - 1, SCREEN_HEIGHT * 2 / 3,
                                 arcade.color.SKY_BLUE)

    # 在屏幕靠下三分之一画绿地
    arcade.draw_rectangle_filled(SCREEN_WIDTH / 2, SCREEN_HEIGHT / 6,
                                 SCREEN_WIDTH - 1, SCREEN_HEIGHT / 3,
                                 arcade.color.DARK_SPRING_GREEN)


def draw_bird(x, y):
    """
    画一只鸟
    """
    arcade.draw_arc_outline(x, y, 20, 20, arcade.color.BLACK, 0, 90)
    arcade.draw_arc_outline(x + 40, y, 20, 20, arcade.color.BLACK, 90, 180)


def draw_pine_tree(center_x, center_y):
    """
    在指定坐标画一颗松树

    Args:
      :center_x: x position of the tree center.
      :center_y: y position of the tree trunk center.
    """
    # 画树杆
    arcade.draw_rectangle_filled(center_x, center_y, 20, 40, arcade.color.DARK_BROWN)

    tree_bottom_y = center_y + 20

    # 画三角形
    point_list = ((center_x - 40, tree_bottom_y),
                  (center_x, tree_bottom_y + 100),
                  (center_x + 40, tree_bottom_y))

    arcade.draw_polygon_filled(point_list, arcade.color.DARK_GREEN)


def draw_birds(window):    # 画所有的鸟
    for bird in window.bird_list:

        # 画这个鸟
        draw_bird(bird[0], bird[1])


def draw_trees(window):

    # 画上排松树
    for x in range(45, SCREEN_WIDTH, 90):
        draw_pine_tree(x, SCREEN_HEIGHT / 3)

    # 画下排松树
    for x in range(65, SCREEN_WIDTH, 90):
        draw_pine_tree(x, (SCREEN_HEIGHT / 3) - 120)


@arcade.decorator.setup
def create_birds(window):
    """这里只是创建一个列表，列表里装着一些坐标对。这些坐标都是随机的，给鸟用。
    This, and any function with the arcade.decorator.init decorator,
    is run automatically on start-up.用了这个装饰器后会在启动时自动运行。
    """

    window.bird_list = []
    for bird_count in range(10):
        x = random.randrange(SCREEN_WIDTH)
        y = random.randrange(SCREEN_HEIGHT / 2, SCREEN_HEIGHT)
        window.bird_list.append([x, y])


@arcade.decorator.update
def animate_birds(window, delta_time):
    """
    每60分之一秒运行一次，这里只是改变坐标。 Do not draw anything
    in this function.
    """
    change_y = 0.3

    for bird in window.bird_list:
        bird[0] += change_y
        if bird[0] > SCREEN_WIDTH + 20:
            bird[0] = -20


@arcade.decorator.draw
def draw(window):
    """
    每60分之一秒运行一次，这里重画所有图形，并不改变坐标。
    """
    # 调用所有画的函数。
    draw_background(window)
    draw_birds(window)
    draw_trees(window)


if __name__ == "__main__":
    arcade.decorator.run(SCREEN_WIDTH, SCREEN_HEIGHT, title="蓝天排松鸟飞图_带装饰器的绘画_译者：李兴球")