Not every part added to the list

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#1

I am trying to make an A* algorithm, but I have a problem. The way script is intended to work, is to get neighbors of current node, and then add the neighbors (that are not in closed list/occupied) to the openList, in which the best part to move at is determined. However, I think I have an issue with this part of code:

local function UpdateNeighbors(Center, Neighbors) -- Detect if neighbors are occupied or already in openList
	for i, neighbor in pairs(Neighbors) do
		if table.find(closedList, neighbor) then continue end
		if table.find(openList, neighbor) then
			if neighbor:GetAttribute("MoveCost") == not 0 and neighbor:GetAttribute("MoveCost") < Center:GetAttribute("MoveCost") + 1 then
				continue
			end
		end
		
		local mCost = Center:GetAttribute("MoveCost") + 1
		neighbor:SetAttribute("MoveCost", mCost)
		
		local hCost = math.abs(finish.Position.X / 8 - neighbor.Position.X / 8) + math.abs(finish.Position.Z / 8 - neighbor.Position.Z / 8)
		neighbor:SetAttribute("TotalCost", mCost + hCost)
		
		neighbor:SetAttribute("CameFrom", Center.CFrame)
		
		table.insert(openList, neighbor)
		
		table.remove(openList, table.find(openList, Center))
		table.insert(closedList, Center)
		
	end
end

The result of this function always puts only 1 part in the list, and not 3 or 4, like it is intended.

If need more context, this is the whole code:

local active = false

local finish = workspace.Nodes.Finish
local start = workspace.Nodes.Start

local upComing

local Nodes = workspace.Nodes:GetChildren()
local openList = {}
local closedList = {}


local function GetNeighbors(Center) -- Get neighbors of current node, AKA upcoming
	
	local neighbors = {}
	
	for i, node in pairs(Nodes) do
		if math.abs(node.Position.X / 8) == math.abs(Center.Position.X / 8) and math.abs(node.Position.Z / 8) == math.abs(Center.Position.Z / 8) + 1 then
			table.insert(neighbors, node)
		elseif math.abs(node.Position.X / 8) == math.abs(Center.Position.X / 8) and math.abs(node.Position.Z / 8) == math.abs(Center.Position.Z / 8) - 1 then
			table.insert(neighbors, node)
		elseif math.abs(node.Position.X / 8) == math.abs(Center.Position.X / 8) + 1 and math.abs(node.Position.Z / 8) == math.abs(Center.Position.Z / 8) then
			table.insert(neighbors, node)
		elseif math.abs(node.Position.X / 8) == math.abs(Center.Position.X / 8) - 1 and math.abs(node.Position.Z / 8) == math.abs(Center.Position.Z / 8) then
			table.insert(neighbors, node)
		end
	end
	
	print(neighbors)
	return neighbors 
	
end

local function UpdateNeighbors(Center, Neighbors) -- Detect if neighbors are occupied or already in openList
	for i, neighbor in pairs(Neighbors) do
		if table.find(closedList, neighbor) then continue end
		if table.find(openList, neighbor) then
			if neighbor:GetAttribute("MoveCost") == not 0 and neighbor:GetAttribute("MoveCost") < Center:GetAttribute("MoveCost") + 1 then
				continue
			end
		end
		
		local mCost = Center:GetAttribute("MoveCost") + 1
		neighbor:SetAttribute("MoveCost", mCost)
		
		local hCost = math.abs(finish.Position.X / 8 - neighbor.Position.X / 8) + math.abs(finish.Position.Z / 8 - neighbor.Position.Z / 8)
		neighbor:SetAttribute("TotalCost", mCost + hCost)
		
		neighbor:SetAttribute("CameFrom", Center.CFrame)
		
		table.insert(openList, neighbor)
		
		table.remove(openList, table.find(openList, Center))
		table.insert(closedList, Center)
		
	end
end

local function UpdateNodes() -- Update nodes: Their color and list references
	for i, node in pairs(Nodes) do
		if node:GetAttribute("Occupied") == true and table.find(closedList, node) then
			continue
		elseif node:GetAttribute("Occupied") == true and not table.find(closedList, node) then
			table.insert(closedList, node)
		end
		
		if table.find(closedList, node) and node:GetAttribute("Occupied") == true then
			node.Color = Color3.fromRGB(60, 0, 0)
		elseif table.find(closedList, node) and node:GetAttribute("Occupied") == false then
			node.Color = Color3.fromRGB(60, 60, 60)
		elseif table.find(openList, node) then
			node.Color = Color3.fromRGB(0, 180, 240)
		end	
	end
end

local function GetUpcoming() -- Get best part for the next iteration
	
	local Costs = {}
	
	for i, node in pairs(openList) do
		local tCost = node:GetAttribute("TotalCost")
		table.insert(Costs, tCost)
	end
	
	local bestCost = math.min(unpack(Costs))
	
	for i, node in pairs(openList) do
		if node:GetAttribute("TotalCost") == bestCost then
			upComing = node
			break
		else 
			continue
		end
	end
	
	return upComing
end

local function Cycle()
	repeat
		UpdateNodes()
		task.wait(1)
		UpdateNeighbors(upComing, GetNeighbors(upComing))
		task.wait(1)
		GetUpcoming()
		print(GetUpcoming())
	until table.find(openList, finish)
end

script.Parent.MouseClick:Connect(function()
	table.insert(openList, start)
	upComing = start
	
	Cycle()
end)
2 Likes
#2

replace == not 0 with ~= 0. character limit

1 Like
#3 
if neighbor:GetAttribute("MoveCost") ~= 0 and neighbor:GetAttribute("MoveCost") < Center:GetAttribute("MoveCost") + 1 then
    continue
end

this should fix it

1 Like
#4

Neither of 2 answers fixed it, sadly.

#5

I kind of fixed it myself. The nodes at the start always have a move cost and total cost of 0, so I had to add additional “if” statement. Got another problem, though, which I will also try to fix, but if I fail, ill ask for help here once again.

#6

what’s the point of this clusterbomb of if statements if the nodes end up in the same table anyway?

there’s no such thing as == not 0, you do ~= 0

#7

They get the neighbors in 4 directions, and because they are in different places, the statements are slightly different. I could have gotten 1 simple statement that would get the magnitude between the center and all other nodes, and if the magnitude is equal or less than 8 then add to the list, but I am planning on doing diagonal movement too, and due to diagonal neighbors having more distance from center, I can’t do that. And yeah, i just forgot that there is ~= existing.

1 Like
#8

image
Made some edit and now it works.