Implement CQuaternion::angleFrom()

include/zeus/CQuaternion.hpp

@@ -274,6 +274,8 @@ public:
     zeus::CVector3f getImaginary() const { return {x, y, z}; }
     void setImaginary(const zeus::CVector3f& i) { x = i.x; y = i.y; z = i.z; }
 
+    CRelAngle angleFrom(const zeus::CQuaternion& other);
+
     inline float& operator[](size_t idx) { return (&w)[idx]; }
     inline const float& operator[](size_t idx) const { return (&w)[idx]; }
 

src/CQuaternion.cpp

@@ -271,4 +271,10 @@ CQuaternion CQuaternion::buildEquivalent() const
     else
         return CQuaternion::fromAxisAngle(CUnitVector3f(x, y, z), tmp + 2.0 * M_PI);
 }
+
+CRelAngle CQuaternion::angleFrom(const zeus::CQuaternion& other)
+{
+    return std::acos(zeus::clamp(-1.f, dot(other), 1.f));
+}
+
 }