From 1328ae42459c4c590bcec6081a413ed738270d00 Mon Sep 17 00:00:00 2001
From: Mateusz Pusz <mateusz.pusz@gmail.com>
Date: Tue, 1 Aug 2023 22:06:15 +0200
Subject: [PATCH] feat: `point_from` added to `quantity_point`

---
 src/core/include/mp-units/quantity_point.h | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/src/core/include/mp-units/quantity_point.h b/src/core/include/mp-units/quantity_point.h
index 8f0b6fcd..5f53eac3 100644
--- a/src/core/include/mp-units/quantity_point.h
+++ b/src/core/include/mp-units/quantity_point.h
@@ -139,6 +139,17 @@ public:
   quantity_point& operator=(const quantity_point&) = default;
   quantity_point& operator=(quantity_point&&) = default;
 
+  template<PointOriginFor<quantity_spec> NewPO>
+  [[nodiscard]] constexpr QuantityPointOf<NewPO{}> auto point_from(NewPO origin) const
+  {
+    if constexpr (detail::is_derived_from_specialization_of_relative_point_origin<NewPO>) {
+      auto q = absolute() - origin.parent_origin.absolute();
+      return quantity_point<reference, NewPO{}, typename decltype(q)::rep>(std::move(q));
+    } else {
+      return quantity_point<reference, NewPO{}, Rep>(absolute());
+    }
+  }
+
   // data access
 #ifdef __cpp_explicit_this_parameter
   template<typename Self>