import?matplotlib.pyplot?as?plt

#?多邊形頂點數
POINTNUM?=?5
#?分辨率
LENGTH?=?600

fig?=?plt.figure（“掃面線填充算法“?figsize=（6?6））
ax?=?fig.add_subplot（1?1?1）
ax.axis（[0?LENGTH?0?LENGTH]）


#?定義邊的結構
class?XET:
????def?__init__（self?x=0.0?dx=0.0?ymax=0）:
????????self.x?=?x
????????self.dx?=?dx
????????self.ymax?=?ymax
????????self.next?=?None


class?Point:
????def?__init__（self?x?y）:
????????self.x?=?x
????????self.y?=?y


points?=?[None]?*?POINTNUM


def?polyScan（）:
????MaxY?=?0
????MinY?=?LENGTH
????for?i?in?range（POINTNUM）:
????????if?points[i].y?>?MaxY:
????????????MaxY?=?points[i].y
????????if?points[i].y?????????????MinY?=?points[i].y
????#?初始化AET表
????AET?=?XET（）
????#?初始化NET表
????NET?=?[None]?*?LENGTH
????for?i?in?range（MaxY?+?1）:
????????NET[i]?=?XET（）
????#?掃描并建立NET表
????for?i?in?range（MaxY?+?1）:
????????for?j?in?range（POINTNUM）:
????????????if?points[j].y?==?i:
????????????????#?一個點跟前面的一個點形成一條線段，跟后面的點也形成線段
????????????????#?如果points[j].y較小就加入
????????????????if?points[（j?-?1?+?POINTNUM）?%?POINTNUM].y?>?points[j].y:
????????????????????p?=?XET（）
????????????????????p.x?=?points[j].x
????????????????????p.ymax?=?points[（j?-?1?+?POINTNUM）?%?POINTNUM].y
????????????????????p.dx?=?（points[（j?-?1?+?POINTNUM）?%?POINTNUM].x?-?points[j].x）?/?（
????????????????????????????????points[（j?-?1?+?POINTNUM）?%?POINTNUM].y?-?points[j].y）
????????????????????p.next?=?NET[i].next
????????????????????NET[i].next?=?p

????????????????if?points[（j?+?1?+?POINTNUM）?%?POINTNUM].y?>?points[j].y:
????????????????????p?=?XET（）
????????????????????p.x?=?points[j].x
????????????????????p.ymax?=?points[（j?+?1?+?POINTNUM）?%?POINTNUM].y
????????????????????p.dx?=?（points[（j?+?1?+?POINTNUM）?%?POINTNUM].x?-?points