Kersten Schuster · Philip Trettner · Philip Trettner
--- a/src/typed-geometry/functions/angle.hh 0 → 100644
+++ b/src/typed-geometry/functions/angle.hh 0 → 100644
+#include <typed-geometry/functions/normal.hh>
+#include <typed-geometry/functions/normalize.hh>
+#include <typed-geometry/tests/vec_tests.hh>
+#include <typed-geometry/types/angle.hh>
+#include <typed-geometry/types/objects/triangle.hh>
+#include <typed-geometry/types/vec.hh>
+
+namespace tg
+{
+// returns the (smaller) angle between two vectors, i.e. the result is in 0..pi (0°..180°)
+template <int D, class ScalarT>
+TG_NODISCARD constexpr angle<fractional_result<ScalarT>> angle_between(vec<D, ScalarT> const& a, vec<D, ScalarT> const& b)
+{
+    auto a_unit = normalize_safe(a);
+    auto b_unit = normalize_safe(b);
+    return acos(clamp(dot(a_unit, b_unit), fractional_result<ScalarT>(0), fractional_result<ScalarT>(1)));
--- a/src/typed-geometry/functions/angle.hh 0 → 100644
+++ b/src/typed-geometry/functions/angle.hh 0 → 100644
+    return acos(clamp(dot(a_unit, b_unit), fractional_result<ScalarT>(0), fractional_result<ScalarT>(1)));
+}
+
+// returns the angle between any two objects with unambiguous normals. The result is in 0..pi (0°..180°)
+template <class A, class B>
+TG_NODISCARD constexpr auto angle_between(A const& a, B const& b) -> decltype(acos(dot(normal(a), normal(b))))
+{
+    return acos(clamp(dot(normal(a), normal(b)), decltype(dot(normal(a), normal(b)))(0), decltype(dot(normal(a), normal(b)))(1)));
+}
+
+// Returns the angle of a rotation of a towards b about the orthogonal_axis
+// The orthogonal axis is important to determine the direction of orientation (axb vs -axb)
+template <class ScalarT>
+TG_NODISCARD constexpr angle<fractional_result<ScalarT>> angle_towards(vec<3, ScalarT> const& a, vec<3, ScalarT> const& b, vec<3, ScalarT> const& orthogonal_axis)
+{
+    TG_ASSERT(are_orthogonal(a, orthogonal_axis));
--- a/src/typed-geometry/functions/rotation.hh
+++ b/src/typed-geometry/functions/rotation.hh
 template <class T>
 TG_NODISCARD constexpr mat<4, 4, T> rotation(angle<T> angle, dir<3, T> const& axis)