Fix Matrix4x4.CreateReflection when D is not zero (dotnet#110057)

* Fix Matrix4x4.CreateReflection * Update tests * Use AssertExtensions instead * Update Matrix4x4Tests.cs * Update Matrix4x4Tests.cs * Use AssertExtensions for new test only --------- Co-authored-by: Tanner Gooding <[email protected]>
mikelle-rogers · Dec 4, 2024 · bef67e1 · bef67e1
1 parent 94477eb
commit bef67e1
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diff --git a/src/libraries/System.Numerics.Vectors/tests/Matrix4x4Tests.cs b/src/libraries/System.Numerics.Vectors/tests/Matrix4x4Tests.cs
@@ -819,11 +819,38 @@ public void Matrix4x4CreateReflectionTest01()
                     Vector3 v = point - pp;
                     float d = Vector3.Dot(v, plane.Normal);
                     Vector3 vp = point - 2.0f * d * plane.Normal;
-                    Assert.True(MathHelper.Equal(rp, vp), "Matrix4x4.Reflection did not provide expected value.");
+                    Assert.True(MathHelper.Equal(rp, vp), "Matrix4x4.CreateReflection did not provide expected value.");
                 }
             }
         }
 
+        [Fact]
+        public void Matrix4x4CreateReflectionTest02()
+        {
+            Plane plane = new Plane(0, 1, 0, 60);
+            Matrix4x4 actual = Matrix4x4.CreateReflection(plane);
+
+            AssertExtensions.Equal(1.0f, actual.M11, 0.0f);
+            AssertExtensions.Equal(0.0f, actual.M12, 0.0f);
+            AssertExtensions.Equal(0.0f, actual.M13, 0.0f);
+            AssertExtensions.Equal(0.0f, actual.M14, 0.0f);
+
+            AssertExtensions.Equal(0.0f, actual.M21, 0.0f);
+            AssertExtensions.Equal(-1.0f, actual.M22, 0.0f);
+            AssertExtensions.Equal(0.0f, actual.M23, 0.0f);
+            AssertExtensions.Equal(0.0f, actual.M24, 0.0f);
+
+            AssertExtensions.Equal(0.0f, actual.M31, 0.0f);
+            AssertExtensions.Equal(0.0f, actual.M32, 0.0f);
+            AssertExtensions.Equal(1.0f, actual.M33, 0.0f);
+            AssertExtensions.Equal(0.0f, actual.M34, 0.0f);
+
+            AssertExtensions.Equal(0.0f, actual.M41, 0.0f);
+            AssertExtensions.Equal(-120.0f, actual.M42, 0.0f);
+            AssertExtensions.Equal(0.0f, actual.M43, 0.0f);
+            AssertExtensions.Equal(1.0f, actual.M44, 0.0f);
+        }
+
         // A test for CreateRotationZ (float)
         [Fact]
         public void Matrix4x4CreateRotationZTest()

diff --git a/src/libraries/System.Private.CoreLib/src/System/Numerics/Matrix4x4.Impl.cs b/src/libraries/System.Private.CoreLib/src/System/Numerics/Matrix4x4.Impl.cs
@@ -620,7 +620,7 @@ public static Impl CreateReflection(in Plane value)
                 // https://github.com/microsoft/DirectXMath/blob/master/Inc/DirectXMathMatrix.inl
 
                 Vector4 p = Plane.Normalize(value).AsVector4();
-                Vector4 s = p * -2.0f;
+                Vector4 s = p * Vector4.Create(-2.0f, -2.0f, -2.0f, 0.0f);
 
                 Impl result;