added test b2AABB_RayCast

Author: ikpil

src/Box2D.NET/B2AABBs.cs

@@ -107,9 +107,7 @@ public static B2CastOutput b2AABB_RayCast(B2AABB a, B2Vec2 p1, B2Vec2 p2)
 
                 if (t1 > t2)
                 {
-                    float tmp = t1;
-                    t1 = t2;
-                    t2 = tmp;
+                    (t1, t2) = (t2, t1);
                     s = 1.0f;
                 }
 
@@ -150,9 +148,7 @@ public static B2CastOutput b2AABB_RayCast(B2AABB a, B2Vec2 p1, B2Vec2 p2)
 
                 if (t1 > t2)
                 {
-                    float tmp = t1;
-                    t1 = t2;
-                    t2 = tmp;
+                    (t1, t2) = (t2, t1);
                     s = 1.0f;
                 }
 

test/Box2D.NET.Test/B2AABBTests.cs

@@ -205,4 +205,55 @@ public void Test_b2IsValidAABB()
         a5.upperBound = new B2Vec2(5, 5);
         Assert.That(b2IsValidAABB(a5), Is.False, "AABB with Infinity value should be invalid.");
     }
+
+    [Test]
+    public void Test_b2AABB_RayCast()
+    {
+        // Case 1: Ray does not intersect the AABB (outside)
+        var aabb1 = new B2AABB();
+        aabb1.lowerBound = new B2Vec2(1, 1);
+        aabb1.upperBound = new B2Vec2(3, 3);
+        var startPoint1 = new B2Vec2(0, 0); // Start point outside AABB
+        var endPoint1 = new B2Vec2(0, 4); // End point (ray direction)
+        var result1 = b2AABB_RayCast(aabb1, startPoint1, endPoint1);
+        Assert.That(result1.hit, Is.False, "Ray should not intersect the AABB.");
+
+        // Case 2: Ray intersects AABB (inside AABB)
+        var aabb2 = new B2AABB();
+        aabb2.lowerBound = new B2Vec2(1, 1);
+        aabb2.upperBound = new B2Vec2(3, 3);
+        var startPoint2 = new B2Vec2(0, 0); // Start point outside AABB
+        var endPoint2 = new B2Vec2(2, 2); // End point (ray direction)
+        var result2 = b2AABB_RayCast(aabb2, startPoint2, endPoint2);
+        Assert.That(result2.hit, Is.True, "Ray should intersect the AABB.");
+        Assert.That(result2.fraction, Is.EqualTo(0.5f), "Intersection point should be correct.");
+
+        // Case 3: Ray starts inside the AABB but goes outside (no intersection outside)
+        var aabb3 = new B2AABB();
+        aabb3.lowerBound = new B2Vec2(1, 1);
+        aabb3.upperBound = new B2Vec2(3, 3);
+        var startPoint3 = new B2Vec2(2, 2); // Start point inside AABB
+        var endPoint3 = new B2Vec2(4, 4); // End point (ray direction goes outside)
+        var result3 = b2AABB_RayCast(aabb3, startPoint3, endPoint3);
+        Assert.That(result3.hit, Is.False, "Ray starting inside but going outside should not intersect.");
+
+        // Case 4: Ray intersects AABB at boundary (exactly on the edge)
+        var aabb4 = new B2AABB();
+        aabb4.lowerBound = new B2Vec2(1, 1);
+        aabb4.upperBound = new B2Vec2(3, 3);
+        var startPoint4 = new B2Vec2(0, 1); // Start point at edge of AABB
+        var endPoint4 = new B2Vec2(4, 1); // End point (ray direction, horizontal)
+        var result4 = b2AABB_RayCast(aabb4, startPoint4, endPoint4);
+        Assert.That(result4.hit, Is.True, "Ray should intersect at the boundary of the AABB.");
+        Assert.That(result4.fraction, Is.EqualTo(0.25f), "Intersection fraction should be 0.25 at the boundary.");
+
+        // Case 5: Ray starts inside and goes out (no intersection outside)
+        var aabb5 = new B2AABB();
+        aabb5.lowerBound = new B2Vec2(1, 1);
+        aabb5.upperBound = new B2Vec2(3, 3);
+        var startPoint5 = new B2Vec2(2, 2); // Start inside AABB
+        var endPoint5 = new B2Vec2(4, 4); // End point (ray direction goes outside)
+        var result5 = b2AABB_RayCast(aabb5, startPoint5, endPoint5);
+        Assert.That(result5.hit, Is.False, "Ray going out of AABB should not intersect.");
+    }
 }