Perfect reflection, and Lambert, for spheres and planes (#1)

RayTracing.Test/TestPlane.fs

@@ -0,0 +1,21 @@
+namespace RayTracing.Test
+
+open NUnit.Framework
+open FsCheck
+open RayTracing
+
+[<TestFixture>]
+module TestPlane =
+
+    [<Test>]
+    let ``Orthogonalise does make orthogonal vectors`` () =
+        let property (p : Plane<float>) : bool =
+            let orth = Plane.orthonormalise Num.float p |> Option.get
+            let v1, v2 = Plane.basis orth
+            Num.float.Equal (Vector.dot Num.float v1.Vector v2.Vector) Num.float.Zero
+            && Num.float.Equal (Vector.dot Num.float v1.Vector v1.Vector) Num.float.One
+            && Num.float.Equal (Vector.dot Num.float v2.Vector v2.Vector) Num.float.One
+
+        property
+        |> Prop.forAll (Arb.fromGen TestUtils.planeGen)
+        |> Check.QuickThrowOnFailure