从前的一个A*

烁灵 posted @ 2015年3月17日 22:53 in Ruby with tags A* 寻路 练习 , 555 阅读

以前的一个a*练习,搬过来凑个数……

A*算法描述见这篇博文

ruby代码:

#encoding=utf-8
MAP = [
		[0, 0, 0, 0, 0, 0, 0, 0],
		[0, 0, 0, 1, 0, 0, 0, 0],
		[0, 0, 0, 1, 0, 0, 0, 0],
		[0, 0, 0, 1, 1, 0, 1, 0],
		[0, 0, 0, 1, 0, 0, 0, 0],
		[0, 0, 0, 1, 0, 0, 0, 0],
		[0, 0, 0, 1, 0, 0, 0, 0],
		[0, 0, 0, 0, 0, 0, 0, 0],		
	  ]		
class Point
	attr_accessor		:x
	attr_accessor		:y
	attr_accessor		:g
	attr_accessor		:h
	attr_accessor		:f
	attr_accessor		:parent
	def initialize(x, y, parent)
		self.x = x
		self.y = y
		self.parent = parent
	end
	def to_s
		"#{super.to_s}, #{[self.x, self.y, self.g, self.h, self.f]}"
	end
end

$open = {}
$close = {}

def find(sx, sy, ex, ey)
	startP = Point.new(sx, sy, nil)
	startP.g = 0
	pos = startP
	while (!$open[[ex, ey]]) do
		dealAround(pos, ex, ey)	# 检查周围元素,计算f
		pos = getMinFPos
	end
	pos = $open[[ex, ey]]
	path = []
	while (pos.parent) do
		path << [pos.x, pos.y]
		pos = pos.parent
	end
	path << [pos.x, pos.y]
	for y in 0...MAP.size
		for x in 0...MAP[0].size
			print (path.include?([x, y])) ? "☆" : (MAP[y][x] == 0 ? "□" : "■")
		end
		print "\r\n"
	end
	p path
end
def getMinFPos
	return nil if $open.size < 1
	minG = $open.values[0].g
	minGPos = $open.values[0]
	$open.values.each{|pos|
		if minG > pos.g
			minG = pos.g
			minGPos = pos
		end
	}
	return minGPos
end
def dealAround(pos, endx, endy)
	# 将pos加入close列表
	$close[[pos.x, pos.y]] = pos	
	# 将pos从open列表中移出
	$open.delete([pos.x, pos.y])
	# 检查周围元素
	[[-1, -1], [0, -1], [1, -1], [-1, 0], [1, 0], [-1, 1], [0, 1], [1, 1]].each{|posOffset|
		# 跳过边界
		next if pos.x + posOffset[0] < 0 or pos.y + posOffset[1] < 0 or pos.x + posOffset[0] > MAP[0].size - 1 or pos.y + posOffset[1] > MAP.size - 1
		# 跳过不可通行的方块
		next if MAP[pos.y + posOffset[1]][pos.x + posOffset[0]] != 0
		# 跳过close列表
		next if $close[[pos.x + posOffset[0], pos.y + posOffset[1]]]
		
		newPos = Point.new(pos.x + posOffset[0], pos.y + posOffset[1], pos)
		# 计算g
		if posOffset[0].abs + posOffset[1].abs == 2 # 斜向
			newPos.g = pos.g + 14
		else
			newPos.g = pos.g + 10
		end
		# 计算h
		newPos.h = (endx - newPos.x).abs * 10 + (endy - newPos.y).abs * 10
		# 计算f
		newPos.f = newPos.g + newPos.h
		# 添加到open列表
		if $open[[newPos.x, newPos.y]] # 已存在
			thePos = $open[[newPos.x, newPos.y]]	
			tempG = ((thePos.x - pos.x).abs + (thePos.y - pos.y).abs == 2) ? (pos.g + 14) : (pos.g + 10)
			if tempG < thePos.g	# 当前节点使g更小
				thePos.g = tempG
				thePos.f = tempG + thePos.h
				thePos.parent = pos	# 修改父节点为当前节点
			end
		else	# 不存在
			$open[[newPos.x, newPos.y]] = newPos
		end
	}
end

find(0, 0, 7, 7)

 


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