inline
SGVec4<T>
normalize(const SGVec4<T>& v)
-{ return (1/norm(v))*v; }
+{
+ T normv = norm(v);
+ if (normv <= SGLimits<T>::min())
+ return SGVec4<T>::zeros();
+ return (1/normv)*v;
+}
/// Return true if exactly the same
template<typename T>
distSqr(const SGVec4<T>& v1, const SGVec4<T>& v2)
{ SGVec4<T> tmp = v1 - v2; return dot(tmp, tmp); }
+// calculate the projection of u along the direction of d.
+template<typename T>
+inline
+SGVec4<T>
+projection(const SGVec4<T>& u, const SGVec4<T>& d)
+{
+ T denom = dot(d, d);
+ T ud = dot(u, d);
+ if (SGLimits<T>::min() < denom) return u;
+ else return d * (dot(u, d) / denom);
+}
+
#ifndef NDEBUG
template<typename T>
inline