2 files changed, 25 insertions, 6 deletions

diff --git a/test.cpp b/test.cpp
index b1e5199..8f413f3 100644
--- a/test.cpp
+++ b/test.cpp
@@ -12,4 +12,23 @@ TEST(Vec, VecAdd) {
 
     vec3d d{1.1, 2.2, 3.3}, e{4.4, 5.5, 6.6}, f{5.5, 7.7, 9.9};
     ASSERT_EQ(d + e, f);
+}
+
+TEST(Vec, VecMin) {
+    vec3i a{1, 1, 1}, b{2, 2, 2}, c{-1, -1, -1};
+    ASSERT_EQ(a - b, c);
+    ASSERT_EQ(-a, c);
+
+    vec3d d{1.1, 2.2, 3.3}, e{-4.4, -5.5, -6.6}, f{5.5, 7.7, 9.9};
+    ASSERT_EQ(d - e, f);
+    ASSERT_EQ(d + (-e), f);
+}
+
+TEST(Vec, VecCrossProduct) {
+    vec3i a{1, 1, 1}, b{2, 2, 2}, c{3, 4, 5}, d{6, 7, 8}, e{-3, -6, -3};
+    ASSERT_EQ(a * b, vec3i{});
+    ASSERT_EQ(c * d, e);
+
+    vec3d f{3.0, 4.0, 5.0}, g{6.0, 7.0, 8.0}, h{-3, -6, -3};
+    ASSERT_EQ(f * g, h);
 }
\ No newline at end of file
diff --git a/vec.h b/vec.h
index 8b5f489..ac6ea44 100644
--- a/vec.h
+++ b/vec.h
@@ -27,7 +27,7 @@ struct vec3 {
     T y;
     T z;
 
-    vec3 operator+(vec3 &b) const {
+    vec3 operator+(const vec3 &b) const {
         return vec3{.x=x + b.x, .y=y + b.y, .z=z + b.z};
     }
 
@@ -35,26 +35,26 @@ struct vec3 {
         return vec3{.x = -x, .y = -y, .z = -z};
     }
 
-    vec3 operator-(vec3 &b) const {
+    vec3 operator-(const vec3 &b) const {
         return vec3{.x=x - b.x, .y=y - b.y, .z=z - b.z};
     }
 
     // cross product
-    vec3 operator*(vec3 &b) const {
+    vec3 operator*(const vec3 &b) const {
         return vec3{.x=y * b.z - z * b.y, .y=x * b.z - z * b.x, .z=x * b.y - y * b.x};
     }
 
-    bool operator==(vec3 b) const {
+    bool operator==(const vec3 b) const {
         return eq(x, b.x) && eq(y, b.y) && eq(z, b.z);
     }
 
     // dot product
-    int dot(vec3 &b) const {
+    int dot(const vec3 &b) const {
         return x * b.x + y * b.y + z * b.z;
     }
 
     // norm value
-    int norm(int level = 2) const {
+    int norm(const int level = 2) const {
         if (level == 2) {
             return std::abs(x * x + y * y + z * z);
         } else if (level == 1) {