Quaternion vector rotation error. #209

glm/gtc/quaternion.inl

@@ -302,11 +302,11 @@ namespace detail
 		detail::tvec3<T, P> const & v
 	)
 	{
-		detail::tvec3<T, P> u(q.x, q.y, q.z);
-		detail::tvec3<T, P> uv(glm::cross(u, v) * q.w);
-		detail::tvec3<T, P> uuv(glm::cross(u, uv));
+		detail::tvec3<T, P> const QuatVector(q.x, q.y, q.z);
+		detail::tvec3<T, P> const uv(glm::cross(QuatVector, v));
+		detail::tvec3<T, P> const uuv(glm::cross(QuatVector, uv));
 
-		return v + (uv + uuv) * static_cast<float>(2);
+		return v + ((uv * q.w) + uuv) * static_cast<T>(2);
 	}
 
 	template <typename T, precision P>

test/gtc/gtc_quaternion.cpp

@@ -247,6 +247,16 @@ int test_quat_type()
 	return 0;
 }
 
+int test_quat_mul_vec()
+{
+	glm::quat q = glm::angleAxis(glm::pi<float>() * 0.5f, glm::vec3(0, 0, 1));
+	glm::vec3 v(1, 0, 0);
+	glm::vec3 u(q * v);
+	glm::vec3 w(u * q);
+
+	return glm::all(glm::epsilonEqual(v, w, 0.01f));
+}
+
 int test_quat_ctr()
 {
 	int Error(0);
@@ -269,6 +279,7 @@ int main()
 	int Error(0);
 
 	Error += test_quat_ctr();
+	Error += test_quat_mul_vec();
 	Error += test_quat_two_axis_ctr();
 	Error += test_quat_mul();
 	Error += test_quat_precision();