Fixing #277

rectangle.go

@@ -222,10 +222,10 @@ func (r Rect) Intersect(s Rect) Rect {
 // This function is overall about 5x faster than Intersect, so it is better
 // to use if you have no need for the returned Rect from Intersect.
 func (r Rect) Intersects(s Rect) bool {
-	return !(s.Max.X < r.Min.X ||
-		s.Min.X > r.Max.X ||
-		s.Max.Y < r.Min.Y ||
-		s.Min.Y > r.Max.Y)
+	return !(s.Max.X <= r.Min.X ||
+		s.Min.X >= r.Max.X ||
+		s.Max.Y <= r.Min.Y ||
+		s.Min.Y >= r.Max.Y)
 }
 
 // IntersectCircle returns a minimal required Vector, such that moving the rect by that vector would stop the Circle

rectangle_test.go

@@ -329,28 +329,56 @@ func TestRect_IntersectionPoints(t *testing.T) {
 	}
 }
 
-func BenchmarkRect_Intersect(b *testing.B) {
-	root := pixel.R(10, 10, 50, 50)
-	inter := pixel.R(11, 11, 15, 15)
+var rectIntTests = []struct {
+	name      string
+	r1, r2    pixel.Rect
+	want      pixel.Rect
+	intersect bool
+}{
+	{
+		name: "Nothing touching",
+		r1:   pixel.R(0, 0, 10, 10),
+		r2:   pixel.R(21, 21, 40, 40),
+		want: pixel.ZR,
+	},
+	{
+		name: "Edge touching",
+		r1:   pixel.R(0, 0, 10, 10),
+		r2:   pixel.R(10, 10, 20, 20),
+		want: pixel.ZR,
+	},
+	{
+		name:      "Bit of overlap",
+		r1:        pixel.R(0, 0, 10, 10),
+		r2:        pixel.R(0, 9, 20, 20),
+		want:      pixel.R(0, 9, 10, 10),
+		intersect: true,
+	},
+	{
+		name:      "Fully overlapped",
+		r1:        pixel.R(0, 0, 10, 10),
+		r2:        pixel.R(0, 0, 10, 10),
+		want:      pixel.R(0, 0, 10, 10),
+		intersect: true,
+	},
+}
 
-	for i := 0; i < b.N; i++ {
-		if root.Intersect(inter) != pixel.ZR {
-			// do a thing
+func TestRect_Intersect(t *testing.T) {
+	for _, tt := range rectIntTests {
+		t.Run(tt.name, func(t *testing.T) {
+			if got := tt.r1.Intersect(tt.r2); !reflect.DeepEqual(got, tt.want) {
+				t.Errorf("Rect.Intersect() = %v, want %v", got, tt.want)
 			}
-
-		// do a thing
+		})
 	}
 }
 
-func BenchmarkRect_IsIntersect(b *testing.B) {
-	root := pixel.R(10, 10, 50, 50)
-	inter := pixel.R(11, 11, 15, 15)
-
-	for i := 0; i < b.N; i++ {
-		if root.Intersects(inter) {
-			// do a thing
+func TestRect_Intersects(t *testing.T) {
+	for _, tt := range rectIntTests {
+		t.Run(tt.name, func(t *testing.T) {
+			if got := tt.r1.Intersects(tt.r2); got != tt.intersect {
+				t.Errorf("Rect.Intersects() = %v, want %v", got, tt.want)
 			}
-
-		// do a thing
+		})
 	}
 }