I need help quickly with building system

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#1

I have a deadline in 2 days and the guy who promised me to help isn’t replying so I need quick help.
The system works like this: You have a baseplate where you can place stuff where you move your mouse (grid). To calculate the boundries I use this function:

local function bounds(cf, offsetX, offsetZ) --cf is the items current position, offsetX is the size.X of the item and the offset Z is the Size.Z of the item
	local LOWER_X_BOUND
	local LOWER_Z_BOUND
	local UPPER_X_BOUND
	local UPPER_Z_BOUND
	
	LOWER_X_BOUND = plot.Position.X - (plot.Size.X*0.5) + offsetX -- plot is the baseplate
	UPPER_X_BOUND = plot.Position.X + (plot.Size.X*0.5) - offsetX
	
	LOWER_Z_BOUND = plot.Position.Z - (plot.Size.Z*0.5) + offsetZ
	UPPER_Z_BOUND = plot.Position.Z + (plot.Size.Z*0.5) - offsetZ
	
	local newX = clamp(cf.X, LOWER_X_BOUND, UPPER_X_BOUND) -- clamp = math.clamp
	local newZ = clamp(cf.Z, LOWER_Z_BOUND, UPPER_Z_BOUND)
	
	return cframe(newX, posY, newZ)  --cframe = CFrame.new
end

But when the baseplate is rotated it doesn’t work. Any idea how to fix this? (there is no need to work with this function. If there is a btter way to work with that it would also be very good. For example: something with raycasting)

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#2

Basically, you’re going to want to convert your cframe into the object space of the base part, do your clamping there, then convert it back to world space.

CFrame has some functions for making this easier.

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#3

Could you write a quick example? Because I never used ToObjectSpace() and the roblox doc doesn’t have any…

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#4

It’s been a while since I’ve really done it so I’m probably going to have done it wrong somehow, but here it goes

local function bounds(cf, offsetX, offsetZ) --cf is the items current position, offsetX is the size.X of the item and the offset Z is the Size.Z of the item
    local objCF = plot.CFrame:ToObjectSpace(cf)

	local LOWER_X_BOUND
	local LOWER_Z_BOUND
	local UPPER_X_BOUND
	local UPPER_Z_BOUND
	
	LOWER_X_BOUND = - (plot.Size.X*0.5) + offsetX -- plot is the baseplate
	UPPER_X_BOUND =  (plot.Size.X*0.5) - offsetX
	
	LOWER_Z_BOUND = - (plot.Size.Z*0.5) + offsetZ
	UPPER_Z_BOUND = (plot.Size.Z*0.5) - offsetZ
	
	local newX = clamp(objCF.X, LOWER_X_BOUND, UPPER_X_BOUND) -- clamp = math.clamp
	local newZ = clamp(objCF.Z, LOWER_Z_BOUND, UPPER_Z_BOUND)
	
    local newCF = cframe(newX, posY, newZ)
	return plot.CFrame:ToWorldSpace(newCF)
end
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#5

But basically toObjectSpace just transforms the cframe to make it be the cframe from the perspective of the baseplate. So we can treat the baseplate as unrotated at the origin and do the calculations since we rotated the cf to compensate. It also translated it for us so I got rid of your translation.

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#6

For some reason the Y position isn’t quite right, but it’s probably a porblem with another function. But other than that it works. Thanks!

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#8

If you’re still here and you could help me with the Y pos then I 'd really appricatne it.

local function calculateYPosition(toP, toS, oS)
	return (toP + toS * 0.5) + oS * 0.5
end

posY = calculateYPosition(mouse.Target.Position.Y, mouse.Target.Size.Y, primary.Size.Y) -- primary = model.primary part (hitbox)
#9

Ok nvm. Chat GPT helped me to solve it. (it wasn’t written by it, but it helped me)

local function calculateYPosition(toP, toS, oS)
	local objSpace = plot.CFrame:ToObjectSpace(CFrame.new(toP.X, toP.Y, toP.Z))  -- Use toP directly
	local newY = (objSpace.Y + toS * 0.5) + oS * 0.5

	return newY
end

posY = calculateYPosition(mouse.Target.Position, mouse.Target.Size.Y, primary.Size.Y) -- primary = model.primary part (hitbox)
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#10

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