Bugfix: vec3::cross was implemented and tested incorrectly.

2 files changed, 9 insertions, 3 deletions

diff --git a/test_vec.cpp b/test_vec.cpp
index 9739160..1c9390f 100644
--- a/test_vec.cpp
+++ b/test_vec.cpp
@@ -25,15 +25,21 @@ TEST(Vec, VecMin) {
 }
 
 TEST(Vec, CrossProduct) {
-    vec3i a{1, 1, 1}, b{2, 2, 2}, c{3, 4, 5}, d{6, 7, 8}, e{-3, -6, -3};
+    vec3i a{1, 1, 1}, b{2, 2, 2}, c{3, 4, 5}, d{6, 7, 8}, e{-3, 6, -3};
     ASSERT_EQ(cross(a, b), vec3i{});
     ASSERT_EQ(a.cross(b), vec3i{});
     ASSERT_EQ(cross(c, d), e);
     ASSERT_EQ(c.cross(d), e);
 
-    vec3d f{3, 4, 5}, g{6, 7, 8}, h{-3, -6, -3};
+    vec3d f{3, 4, 5}, g{6, 7, 8}, h{-3, 6, -3};
     ASSERT_EQ(cross(f, g), h);
     ASSERT_EQ(f.cross(g), h);
+
+    vec3d u{2, -2, -2}, v{2.5, -5, -2.5}, w{-5, 0, -5};
+    ASSERT_EQ(cross(u, v), w);
+
+    vec3d x{1.6, 3.5, 11}, y{3, 7, 15}, z{-24.5, 9, 0.7};
+    ASSERT_EQ(cross(x, y), z);
 }
 
 TEST(Vec, DotProduct) {
diff --git a/vec.h b/vec.h
index e3e15b8..84cbaa3 100644
--- a/vec.h
+++ b/vec.h
@@ -76,7 +76,7 @@ struct vec3 {
 
     // cross product (aka outer product, or vector product, producing a vector)
     vec3 cross(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};
+        return vec3{.x=y * b.z - z * b.y, .y=z * b.x - x * b.z, .z=x * b.y - y * b.x};
     }
 
     // Multiply with b on every dimension.