Question on EgoMooses Placing System

Help and Feedback Scripting Support
#1 
function Placement:CalcCanvas()
	local canvasSize = self.CanvasPart.Size

	-- want to create CFrame such that cf.lookVector == self.CanvasPart.CFrame.upVector
	-- do this by using object space and build the CFrame
	local back = Vector3.new(0, -1, 0)
	local top = Vector3.new(0, 0, -1)
	local right = Vector3.new(-1, 0, 0)

	-- convert to world space
	local cf = self.CanvasPart.CFrame * CFrame.fromMatrix(-back*canvasSize/2, right, top, back)
	-- use object space vectors to find the width and height
	local size = Vector2.new((canvasSize * right).magnitude, (canvasSize * top).magnitude)

	return cf, size
end

why is

local back = Vector3.new(0, -1, 0)
when back is supposed to be (0,0,1)
local top = Vector3.new(0, 0, -1)
when top is supposed to be (0,1,0)
local right = Vector3.new(-1, 0, 0)
when right is supposed to be (1,0,0)

#2

You could’ve replied to the original post, or personally DM EgoMoose for this though

As stated above the variables, these are used to form the rotation matrix of a CFrame to orient the part in such a way that makes the part’s front surface face the upvector of CanvasPart’s CFrame, which by looking at the variables used, makes it face the global upvector

I used the same code, but changed it a bit of course, and the part was oriented in a way that makes its front surface face upwards:

image
image1025×578 268 KB

Printing the Right, Up and LookVectors of course returned the variables back:

image
image920×64 2.35 KB

#3

is there a article about matrixes?

#4