How do I make a Dragger?

[arxlfox (ar_lfox)]

I’m making a module script for a game that requires some sort of building system. Roblox Studio’s method of placing parts is perfect for what I’m doing. How can I make something similar?

1. What happened to DraggerService? I searched through the docs and api and found DraggerService, but cannot access it in game. Being able to use DraggerService (for increments and other things) with Draggers will solve my issue.

2. How do I do the same thing Roblox is doing? I’ve been through the forum and found some posts about it, but none of them (except this one, but I can’t load the .rbxm file as apparently its corrupted.) presents a solid solution I can use.
   

Here’s a snippet of my current code/module, made with some help from existing forum posts:

local function ConvertWithIncrement(v3: Vector3, increment: number, size, unitNormal)
	local x, y, z = v3.X, v3.Y, v3.Z
    if increment > 0 then
    	x = math.sign(x)*((math.abs(x) - math.abs(x) % increment) + (size.X % increment))
    	y = math.sign(y)*((math.abs(y) - math.abs(y) % increment) + (size.Y % increment))
    	z = math.sign(z)*((math.abs(z) - math.abs(z) % increment) + (size.Z % increment))
    end
	return Vector3.new(x, y, z)
end

function Dragger:MouseMove(unitRay: Ray, params: RaycastParams)
	
	local rayStart = unitRay.Origin
	local rayDirection = unitRay.Direction
	
	if self.Target then
		if not params then
			params = RaycastParams.new()
			params.FilterType = Enum.RaycastFilterType.Exclude
			params.IgnoreWater = true
			params.FilterDescendantsInstances = {self.Target}
		end
		
		local hit = game.Workspace:Raycast(rayStart, rayDirection * self.RaycastRange, params)
		if hit and hit.Instance then
			local pos = hit.Position
			
			-- offset by the face of the target
			local size
			if self.Target.ClassName == "Model" then
				local normClone = self.Target:Clone()
				normClone.Parent = game.ReplicatedStorage
				normClone:PivotTo(CFrame.new(0,0,0))
				_, size = normClone:GetBoundingBox()
			else
				size = self.Target.Size
			end
			pos += hit.Normal * (size/2)
			
			-- grid locking
			pos = ConvertWithIncrement(pos, self.Increment, size, hit.Normal)
			
			local c = CFrame.new(pos, pos + hit.Normal)
			--c *= CFrame.Angles(math.rad(hit.Instance.Orientation.X), math.rad(hit.Instance.Orientation.Y), math.rad(hit.Instance.Orientation.Z))
			
			if self.Target.ClassName == "Model" then
				self.Target:PivotTo(c)
			else
				self.Target.CFrame = c
			end
		end
	else
		warn("No target was found.")
	end
end

The script works the best when the snap increment is 0. Otherwise, the position is snapped “globally”, and so the part can clip into the part it is being placed on.
Another issue is that unlike in Roblox’s dragger system, the part’s orientation doesn’t match up with the part its being placed on.

Current:

Snap and orientation are off
Expected:

Snap and orientation matches that of the canvas part

EDIT:
I looked through again and found this. How do you use/find the “new framework”?

[dthecoolest]

Have you checked this out?

FE Dragger Instance?

Clonetrooper released a FE-compatible set of build tools recently: You should be able to use these.

[arxlfox (ar_lfox)]

Yes, its a really neat system of using the Dragger object, except there still isn’t a way to change the increment and other things Roblox’s draggers can use because it still uses a Dragger object.

If i can fix the file corruption issue and open the file i think i can just look at roblox’s code to see how their dragger works. I dont know why it says its corrupted or if im doing something wrong

Or is it possible for you to send me your studio’s MoveDragger.rbxm file (if that is the file roblox uses for dragging objects in the scene editor)?

Then again, I don’t really know if you can just “import” the .rbxm file from the builtinplugins folder, but when I open the file with notepad it shows a bunch of…not code

EDIT:
This post also shows that there is a lua file somewhere that developers can use to see how the draggers work. Is this the BuiltInPlugin/MoveDragger.rbxm file?

[arxlfox (ar_lfox)]

YESS okay I found a good solution

I went and revisited this, and realised i can just use the other part as the ‘canvas’

Heres the completed code if anyone cares:

local Dragger = {ClassName = "Dragger"}
Dragger.__index = Dragger

function Dragger.new()
	local self = {}
	self.Target = nil

	-- to be set manually
	self.Increment = 0
	self.RaycastRange = 100

	setmetatable(self, Dragger)
	return self
end

function Dragger:MouseDown(target: "Part/Model to move")
	self.Target = target
end

function Dragger:CalcCanvas(canvas)
	local canvasSize = canvas.Size

	local up = Vector3.new(0, 1, 0)
	local back = -self.SurfaceVector

	local dot = back:Dot(Vector3.new(0, 1, 0))
	local axis = (math.abs(dot) == 1) and Vector3.new(-dot, 0, 0) or up

	local right = CFrame.fromAxisAngle(axis, math.pi/2) * back
	local top = back:Cross(right).unit

	local cf = canvas.CFrame * CFrame.fromMatrix(-back*canvasSize/2, right, top, back)
	local size = Vector2.new((canvasSize * right).magnitude, (canvasSize * top).magnitude)

	return cf, size
end
function Dragger:CalcPlacementCFrame(position, rotation, surfaceVector, canvas)
	self.SurfaceVector = surfaceVector
	local cf, size = self:CalcCanvas(canvas)

	local tSize = self.Target.Size
	if self.Target.ClassName == "Model" then tSize = self.Target.PrimaryPart.Size end

	local modelSize = CFrame.fromEulerAnglesYXZ(0, rotation, 0) * tSize
	modelSize = Vector3.new(math.abs(modelSize.x), math.abs(modelSize.y), math.abs(modelSize.z))

	local lpos = cf:pointToObjectSpace(position);
	local size2 = (size - Vector2.new(modelSize.x, modelSize.z))/2

	if size2.x < 0 or size2.y < 0 then return end

	local x = math.clamp(lpos.x, -size2.x, size2.x);
	local y = math.clamp(lpos.y, -size2.y, size2.y);

	local g = self.Increment
	if (g > 0) then
		x = math.sign(x)*((math.abs(x) - math.abs(x) % g) + (size2.x % g))
		y = math.sign(y)*((math.abs(y) - math.abs(y) % g) + (size2.y % g))
	end

	return cf * CFrame.new(x, y, -modelSize.y/2) * CFrame.Angles(-math.pi/2, rotation, 0)
end

function Dragger:MouseMove(unitRay: Ray, params: RaycastParams)

	local rayStart = unitRay.Origin
	local rayDirection = unitRay.Direction

	if self.Target then
		if not params then
			params = RaycastParams.new()
			params.FilterType = Enum.RaycastFilterType.Exclude
			params.IgnoreWater = true
			params.FilterDescendantsInstances = {self.Target}
		end

		local hit = game.Workspace:Raycast(rayStart, rayDirection * self.RaycastRange, params)
		if hit and hit.Instance and hit.Instance ~= game.Workspace.Terrain then
			local pos = hit.Position

			local surface
			local dotY = hit.Normal:Dot(Vector3.new(0,1,0))
			local dotX = hit.Normal:Dot(Vector3.new(1,0,0))
			local dotZ = hit.Normal:Dot(Vector3.new(0,0,1))
			if (math.abs(dotY) >= 0.9) then
				if (dotY < 0) then
					surface = Enum.NormalId.Bottom
				else
					surface = Enum.NormalId.Top
				end
			elseif (math.abs(dotX) >= 0.9) then
				if (dotX < 0) then
					surface = Enum.NormalId.Left
				else
					surface = Enum.NormalId.Right
				end
			else
				if (dotZ < 0) then
					surface = Enum.NormalId.Front
				else
					surface = Enum.NormalId.Back
				end
			end

			local c = self:CalcPlacementCFrame(pos, 0, Vector3.FromNormalId(surface), hit.Instance)


			if not c then return end

			if self.Target.ClassName == "Model" then
				self.Target:PivotTo(c)
			else
				self.Target.CFrame = c
			end
		end
	else
		warn("No target was found.")
	end
end

function Dragger:MouseUp()
	self.Target = nil
end

return Dragger