fix direction in alternative Line constructor

src/Sets/Line/Line.jl

@@ -38,7 +38,7 @@ arguments, and returns the line through them. See the algorithm section for
 details.
 
 ```jldoctest
-julia> Line(from=[-1.0, 2, 3], to=[-4.0, 2, 4])
+julia> Line(from=[-1.0, 2, 3], to=[2.0, 2, 2])
 Line{Float64, Vector{Float64}}([-1.0, 2.0, 3.0], [3.0, 0.0, -1.0])
 ```
 
@@ -48,7 +48,7 @@ lines. It takes two inputs, `a` and `b`, and constructs the line such that
 
 ```jldoctest
 julia> Line([2.0, 0], 1.)
-Line{Float64, Vector{Float64}}([0.5, 0.0], [0.0, -1.0])
+Line{Float64, Vector{Float64}}([0.5, 0.0], [0.0, 1.0])
 ```
 
 ### Algorithm
@@ -73,7 +73,7 @@ struct Line{N,VN<:AbstractVector{N}} <: AbstractPolyhedron{N}
 end
 
 function Line(; from::AbstractVector, to::AbstractVector, normalize=false)
-    d = from - to
+    d = to - from
     @assert !iszero(d) "points `$from` and `$to` should be distinct"
     return Line(from, d; normalize=normalize)
 end

test/Sets/Line.jl

@@ -7,6 +7,7 @@ for N in [Float64, Rational{Int}, Float32]
     # construction
     l1 = Line(; from=N[0, 1], to=N[1, 1]) # two points on the line
     l2 = Line(N[0, 1], N[1, 0]) # point and direction
+    @test l1.p ≈ l2.p && l1.d ≈ l2.d  # the lines are the same
 
     # construction given a 2d direction and offset
     ll = Line(N[0, 1], N(1)) # y == 1
@@ -17,9 +18,6 @@ for N in [Float64, Rational{Int}, Float32]
     @test N[0, 0] ∈ ll && N[1, 1] ∈ ll
     @test_throws ArgumentError Line(zeros(N, 2), N(0))
 
-    # the lines are the same modulo the sign of the normal vector
-    @test l1.p ≈ l2.p && l1.d ≈ -l2.d
-
     # direction
     @test direction(l2) == N[1, 0]