Merge pull request #3 from dotnet-campus/t/sewzc/fix_segment_intersec…

…tion

修复线段计算没有交点的问题

DotNetCampus.Numerics.Geometry.Tests/Segment2DTest.cs

@@ -0,0 +1,75 @@
+using JetBrains.Annotations;
+using Xunit;
+
+namespace DotNetCampus.Numerics.Geometry.Tests;
+
+[TestSubject(typeof(Segment2D))]
+public class Segment2DTest
+{
+    #region 成员方法
+
+    [Fact(DisplayName = "测试线段交点。")]
+    public void IntersectionTest()
+    {
+        // Arrange
+        var point1 = new Point2D(0, 0);
+        var point2 = new Point2D(4, 4);
+        var segment1 = Segment2D.Create(point1, point2);
+
+        var point3 = new Point2D(0, 4);
+        var point4 = new Point2D(4, 0);
+        var segment2 = Segment2D.Create(point3, point4);
+
+        var expectedIntersection = new Point2D(2, 2);
+
+        // Act
+        var intersection = segment1.Intersection(segment2);
+
+        // Assert
+        Assert.NotNull(intersection);
+        Assert.Equal(expectedIntersection, intersection.Value, GeometryNumericsEqualHelper.IsAlmostEqual);
+    }
+
+    [Fact(DisplayName = "测试平行线段无交点。")]
+    public void ParallelSegmentsNoIntersectionTest()
+    {
+        // Arrange
+        var point1 = new Point2D(0, 0);
+        var point2 = new Point2D(4, 0);
+        var segment1 = Segment2D.Create(point1, point2);
+
+        var point3 = new Point2D(0, 1);
+        var point4 = new Point2D(4, 1);
+        var segment2 = Segment2D.Create(point3, point4);
+
+        // Act
+        var intersection = segment1.Intersection(segment2);
+
+        // Assert
+        Assert.Null(intersection);
+    }
+
+    [Fact(DisplayName = "测试线段端点相交。")]
+    public void EndpointIntersectionTest()
+    {
+        // Arrange
+        var point1 = new Point2D(4, 8);
+        var point2 = new Point2D(4, 4);
+        var segment1 = Segment2D.Create(point1, point2);
+
+        var point3 = new Point2D(4, 4);
+        var point4 = new Point2D(8, 8);
+        var segment2 = Segment2D.Create(point3, point4);
+
+        var expectedIntersection = new Point2D(4, 4);
+
+        // Act
+        var intersection = segment1.Intersection(segment2);
+
+        // Assert
+        Assert.NotNull(intersection);
+        Assert.Equal(expectedIntersection, intersection.Value, GeometryNumericsEqualHelper.IsAlmostEqual);
+    }
+
+    #endregion
+}

DotNetCampus.Numerics.Geometry/Segment2D.cs

@@ -60,7 +60,7 @@ public static Segment2D Create(Point2D point1, Point2D point2)
         var position = vector.Det(other.UnitDirectionVector) / det;
         var radio = position / Length;
         var radio2 = vector.Det(UnitDirectionVector) / det / other.Length;
-        if (radio.IsInZeroToOne() || radio2.IsInZeroToOne())
+        if (!radio.IsInZeroToOne() || !radio2.IsInZeroToOne())
             return null;
 
         return Line.GetPoint(position);

DotNetCampus.Numerics.Tests/NumAssert.cs

@@ -58,11 +58,5 @@ public static void NotCloseZero<TNum>(TNum actual)
             throw new NotSupportedException($"暂时不支持类型 {typeof(TNum).FullName}。");
     }
 
-    public static void Equal<TNum>(TNum expected, TNum actual)
-        where TNum : unmanaged, IFloatingPoint<TNum>
-    {
-        Assert.Equal(expected, actual);
-    }
-
     #endregion
 }