Orienting a Part to Mouse TargetSurface

[FoolsOfAFeather (ChocolateWithNuts)]

Hi, I have searched through many other similar topics with no avail.

What I am trying to achieve is to get the direction of surface (right, top, front, etc.) with something like Mouse.TargetSurface. To place an object parallel to something like a wall.

Simply, I am making a placement system that attaches a part smoothly to a wall.

Is this possible, or is brute forcing needed?

[Geolio9 (Tomate)]

If you know for a fact that the walls are going to be square and flat, I would use the dot product of the normal at the mouse ray hit.

[FoolsOfAFeather (ChocolateWithNuts)]

Can you explain how to get a dot product?

[Geolio9 (Tomate)]

I would go about it by determining the direction with the greatest dot product with the normal. If you want to get the normal * direction, you can just do:

local dot = Normal:Dot(Direction)

[FoolsOfAFeather (ChocolateWithNuts)]

I have the dot product. But how would I convert that to a parts orientation?

local raycastResult = game.Workspace:Raycast(Mouse.UnitRay.Origin, Mouse.UnitRay.Direction * 50)
		
		if raycastResult then
			
			local Normal = raycastResult.Normal
			
			print(Normal:Dot(Mouse.UnitRay.Direction))
			
			
		else	
			print("false")
		end

[Geolio9 (Tomate)]

The Direction should be positive and negative basis vectors (like +x, -x, +y, -y, +z, -z)

[FoolsOfAFeather (ChocolateWithNuts)]

Could you tell me how to get basis vectors and how to orient a part from the dot product

[Geolio9 (Tomate)]

I think I misunderstood your problem…

[Geolio9 (Tomate)]

Do you want to position it so it’s on the wall or snap to the direction the surface is closest to?

[FoolsOfAFeather (ChocolateWithNuts)]

Snap to the direction the surface is closest to.

[Geolio9 (Tomate)]

It would actually probably less expensive and less complex to just get the greatest (with absolute value) component of the normal vector and use that as the direction.

local normalDict = {
   ["X"] = normal.Unit * Vector3.new(1, 0, 0);
   ["Y"] = normal.Unit * Vector3.new(0, 1, 0);
   ["Z"] = normal.Unit * Vector3.new(0, 0, 1);
}

for axis, value in pairs(normalDict) do
   local sign = math.sign(value[axis])
   if value[axis] * sign > math.sqrt(3)/3 then
      local primaryAxis = value.Unit
   end
end

[Geolio9 (Tomate)]

You can use CFrame.lookAlong() to get the cframe angles to position a part.

local angles = CFrame.lookAlong(Vector3.new(), primaryAxis)

[FoolsOfAFeather (ChocolateWithNuts)]

Simpler solution with no math

if Mouse.TargetSurface == Enum.NormalId.Front then
			
			Real.Orientation = Mouse.Target.Orientation + Vector3.new(-90, 0, 0)
			
		elseif Mouse.TargetSurface == Enum.NormalId.Back then
			
			Real.Orientation = Mouse.Target.Orientation + Vector3.new(-90, 180, 0)
			
		elseif Mouse.TargetSurface == Enum.NormalId.Right then
			
			Real.Orientation = Mouse.Target.Orientation + Vector3.new(-90, -90, 0)
			
		elseif Mouse.TargetSurface == Enum.NormalId.Left then
			
			Real.Orientation = Mouse.Target.Orientation + Vector3.new(-90, 90, 0)
			
		elseif Mouse.TargetSurface == Enum.NormalId.Top then

			Real.Orientation = Mouse.Target.Orientation + Vector3.new(0, 90, 0)
			
		elseif Mouse.TargetSurface == Enum.NormalId.Bottom then

			Real.Orientation = Mouse.Target.Orientation + Vector3.new(-90, 90, 0)
			
		end