from math import sin, cos, radians
# 模拟重力
GRAVITY = 0.1
class Particle(object):
def __init__(self, cv, idx, total, explosion_speed, explosion_radius=1, x=0., y=0., vx=0., vy=0., size=2., color='red', lifespan=2):
"""
粒子在空中随机生成随机，变成一个圈、下坠、消失
属性:
- id: 粒子的id
- x, y: 粒子的坐标
- vx, vy: 在坐标的变化速度
- total: 总数
- age: 粒子存在的时长
- color: 颜色
- cv: 画布
- lifespan: 最高存在时长
"""
self.id = idx
self.x = x
self.y = y
self.initial_speed = explosion_speed
self.explosion_radius = explosion_radius
self.vx = vx
self.vy = vy
self.total = total
self.age = 0
self.color = color
self.cv = cv
self.cid = self.cv.create_oval(
x - size, y - size, x + size,
y + size, fill=self.color)
self.lifespan = lifespan
def update(self, dt):
self.age += dt
# 粒子范围扩大
if self.alive() and self.expand():
move_x = cos(radians(self.id * 360 / self.total)) * self.initial_speed
move_y = sin(radians(self.id * 360 / self.total)) * self.initial_speed
self.cv.move(self.cid, move_x * self.explosion_radius, move_y * self.explosion_radius)
self.vx = move_x / (float(dt) * 1000)
# 以自由落体坠落
elif self.alive():
move_x = cos(radians(self.id * 360 / self.total))
# we technically don't need to update x, y because move will do the job
self.cv.move(self.cid, self.vx + move_x, self.vy + GRAVITY * dt)
self.vy += GRAVITY * dt
# 移除超过最高时长的粒子
elif self.cid is not None:
self.cv.delete(self.cid)
self.cid = None
# 扩大的时间
def expand(self):
return self.age <= 1.2
# 粒子是否在最高存在时长内
def alive(self):
return self.age <= self.lifespan
