Hey there 
So yeah, I’ve worked on this thing for probably about an hour? I don’t have much use for it but it was a fun project and if anyone wants the source code, I’ll open source it. Anyways here are some examples of what it does:
Inspect the source code and critique at will haha:
Polygon Triangulation [open source[ - Roblox
I’m aware it’s a bit clunky and also requires each node to be connected directly in terms of the numbering. Don’t overlap nodes!
Looks awesome! 
Would’ve used the same thing for my floor building system, but it seems a bit too complicated for me to wrap my head around ahaha
I’d love to check it out myself if you don’t mind!
Good work! Which polygon triangulation algorithm did you use?
I’ve attached a link in the post.
@AstroCode Honestly… I don’t know if anyone has coined it with a name yet. It’s fairly standard in the sense that the algorithm removes ears from the polygon up until it considers the polygon complete. There’s quite a few inefficiencies because honestly, I’m not so good with computer graphics yet 
I used these resources:
http://www.personal.kent.edu/~rmuhamma/Compgeometry/MyCG/TwoEar/two-ear.htm
http://cgm.cs.mcgill.ca/~godfried/teaching/cg-projects/97/Ian/algorithm2.html
That’s called the ear clipping method. I used it in a program a couple months back and found the Wikipedia article an interesting read. Polygon triangulation - Wikipedia
I’m using this resource, but how can I fix this hole?
here is my script
local function CreatePolygonFromPoints(Points)
local Polygon = {}
local First = Polygon
for i = 1, #Points do
Polygon.Position = Points[i]
Polygon.NodeId = i
if i ~= #Points then
Polygon.Next = {Previous = Polygon}
Polygon = Polygon.Next
end
local A, B, C = GetPoint("Behind", i, Points), Points[i], GetPoint("Front", i, Points)
drawTriangle(A, B, C, workspace.Debug)
end
Polygon.Next, First.Previous = First, Polygon
return First
end
function GetPoint(Type, Point, ListofPoint)
if Type == "Behind" then
if Point == 1 then
return ListofPoint[#ListofPoint]
else
return ListofPoint[Point - 1]
end
elseif Type == "Front" then
if Point == #ListofPoint then
return ListofPoint[1]
else
return ListofPoint[Point + 1]
end
end
return false
end
local wedge = Instance.new("WedgePart")
wedge.Material = Enum.Material.SmoothPlastic
wedge.Transparency = 0
wedge.Anchored = true
wedge.CanCollide = false
wedge.TopSurface = Enum.SurfaceType.Smooth
wedge.BottomSurface = Enum.SurfaceType.Smooth
wedge.Color = Color3.fromRGB(125, 125, 125)
local wedgeMesh = Instance.new("SpecialMesh", wedge)
wedgeMesh.MeshType = Enum.MeshType.Wedge
wedgeMesh.Scale = Vector3.new(1,1,1)
function drawTriangle(a, b, c, parent)
local edges = {
{longest = (c - b), other = (a - b), position = b};
{longest = (a - c), other = (b - c), position = c};
{longest = (b - a), other = (c - a), position = a};
};
table.sort(edges, function(a, b) return a.longest.magnitude > b.longest.magnitude end);
local edge = edges[1];
local theta = math.acos(edge.longest.unit:Dot(edge.other.unit))
local s1 = Vector2.new(edge.other.magnitude * math.cos(theta), edge.other.magnitude * math.sin(theta));
local s2 = Vector2.new(edge.longest.magnitude - s1.x, s1.y);
local p1 = edge.position + edge.other * 0.5
local p2 = edge.position + edge.longest + (edge.other - edge.longest) * 0.5
local right = edge.longest:Cross(edge.other).unit;
local up = right:Cross(edge.longest).unit;
local back = edge.longest.unit;
local cf1 = CFrame.new(
p1.x, p1.y, p1.z,
-right.x, up.x, back.x,
-right.y, up.y, back.y,
-right.z, up.z, back.z
);
local cf2 = CFrame.new(
p2.x, p2.y, p2.z,
right.x, up.x, -back.x,
right.y, up.y, -back.y,
right.z, up.z, -back.z
);
local w1 = wedge:Clone();
local w2 = wedge:Clone();
w1.Parent = parent;
w2.Parent = parent;
w1.Size = Vector3.new(0.01, s1.y, s1.x);
w2.Size = Vector3.new(0.01, s2.y, s2.x);
w1.CFrame = cf1;
w2.CFrame = cf2;
end;
local points = {}
for i, v in next, workspace.Model:GetChildren() do table.insert(points, v.Position) end
CreatePolygonFromPoints(points)
I have no idea how to fix this
anhtuan159, that script is partially correct in choosing the closest two points. However, to fill the whole area (… or to fill the hole, same same), the triangle drawing algorithm needs to additively progress from a starting point.
Think of following along the circumference of a circle in a constant direction of rotation, either clockwise or counter-clockwise, but you have to pick one direction and stick with it in order to fill the polygon using triangles connecting an existing set of points.
So, you can’t just accept the order of the table of children returned from workspace.Model:GetChildren() and then draw triangles (wedge parts) between a part and its closest two parts. You need to determine a specific order of parts around the perimeter.
Once this is done, a new point created at a later time can be added to the polygon by drawing a triangle from this new point to its closest two neighbour points, continuing the fill process.
OP’s source script does this progressive rotation triangle fill. Try editing the place posted at the top of this thread to see how its done. Just slow down the wait to watch it happen. On line 109, change wait() to wait(1) or some higher value.
function TriangulatePolygon(points)
local folder = Instance.new("Folder", game.Workspace)
while true do
local newTable = points
local done = false
while #newTable > 2 do
done,newTable = GetEarOfPolygon(newTable, -1, folder)
table.sort(newTable, function(a,b) return tonumber(a.Name) < tonumber(b.Name) end)
wait(1) -- set to 1 or higher to watch triangles fill the polygon
end
wait(2)
folder:ClearAllChildren()
end
end
Instead of while loops I feel like this could be done easier with recursion.
Right? Also avoid Wait()
I’m just responding to the posted code examples and answering to the general idea of polygon fill using triangles.
Meant to state specifically the order of points for additively filling the polygon is:
After a polygon is filled and then a new point is added, the procedure is no longer rotating around the perimeter, so it can switch to using the current point and the closest two points.
Thanks for the clarity! I admit I posted this code partially to help out and also partially because I wanted more experienced members to weigh in on what to improve. You’ve helped a bunch 
Hi,
for some reason, it’s not working properly for me. It doesn’t work in one direction at all, and when I have more than 5 points then it starts to bug for me. And is there a way how to detect that it’s not possible to construct the triangles?
btw I’m using the original code Polygon Triangulation [open source[ - Roblox, I didn’t change anything.
robloxapp-20220416-0912112.wmv (2.5 MB)
thanks for any help!
This code is most likely outdated and probably not up to date. You should use other methods or use a plugin
Came across this post, proved to be pretty useful but encountered the same problem as a few others.
To solve this, I added a method to check if the points inside the table are clockwise or anti-clockwise then you can determine the direction based on if the number is negative or positive. This will probably solve most peoples issues with finding the direction and table sorting errors.
function CheckIsClockwise(points)
local Sum = 0
for i=1, #points do
if points[i+1] then
Sum += (math.abs(points[i+1].Position.X) - math.abs(points[i].Position.X))*(math.abs(points[i+1].Position.Z) + math.abs(points[i].Position.Z))
else
Sum += (math.abs(points[1].Position.X) - math.abs(points[i].Position.X))*(math.abs(points[1].Position.Z) + math.abs(points[i].Position.Z))
end
end
return Sum
end
function TriangulatePolygon(points)
local Direction = CheckIsClockwise(points)
if Direction > 0 then
Direction = 1
else
Direction = -1
end
table.sort(points, function(a,b) return tonumber(a.Name) < tonumber(b.Name) end)
local folder = Instance.new("Folder", game.Workspace)
while true do
local newTable = points
local done = false
while #newTable > 2 do
done,newTable = GetEarOfPolygon(newTable, Direction, folder)
table.sort(newTable, function(a,b) return tonumber(a.Name) < tonumber(b.Name) end)
end
break
end
endamazing work! that will help me a lot!