math: add Box2d + vec2 operations for easy box translations.

src/lol/math/geometry.h

@@ -40,6 +40,30 @@ struct Box2D
         B(b)
     {}
 
+    Box2D operator +(vec2 v)
+    {
+        return Box2D(A + v, B + v);
+    }
+
+    Box2D &operator +=(vec2 v)
+    {
+        A += v;
+        B += v;
+        return *this;
+    }
+
+    Box2D operator -(vec2 v)
+    {
+        return Box2D(A - v, B - v);
+    }
+
+    Box2D &operator -=(vec2 v)
+    {
+        A -= v;
+        B -= v;
+        return *this;
+    }
+
     vec2 A, B;
 };
 
@@ -55,6 +79,30 @@ struct Box3D
         B(b)
     {}
 
+    Box3D operator +(vec3 v)
+    {
+        return Box3D(A + v, B + v);
+    }
+
+    Box3D &operator +=(vec3 v)
+    {
+        A += v;
+        B += v;
+        return *this;
+    }
+
+    Box3D operator -(vec3 v)
+    {
+        return Box3D(A - v, B - v);
+    }
+
+    Box3D &operator -=(vec3 v)
+    {
+        A -= v;
+        B -= v;
+        return *this;
+    }
+
     vec3 A, B;
 };
 

test/unit/box.cpp

@@ -38,6 +38,21 @@ LOLUNIT_FIXTURE(BoxTest)
 
         LOLUNIT_ASSERT_EQUAL(false, BoxIsectBox(b4, b5));
     }
+
+    LOLUNIT_TEST(Box2DMove)
+    {
+        Box2D b1(vec2(0.f, 0.f), vec2(1.f, 1.f));
+        Box2D b2(vec2(2.f, 2.f), vec2(3.f, 3.f));
+
+        b1 += vec2(0.6f, 0.6f);
+        LOLUNIT_ASSERT_EQUAL(false, BoxIsectBox(b1, b2));
+
+        b1 += vec2(0.6f, 0.6f);
+        LOLUNIT_ASSERT_EQUAL(true, BoxIsectBox(b1, b2));
+
+        b1 -= vec2(0.0f, 0.6f);
+        LOLUNIT_ASSERT_EQUAL(false, BoxIsectBox(b1, b2));
+    }
 };
 
 } /* namespace lol */