From 4571ce1b4cac2ab9bf2454ed06d0d787604d62fa Mon Sep 17 00:00:00 2001
From: Dan Goodliffe <dan@randomdan.homeip.net>
Date: Thu, 21 Mar 2024 20:23:44 +0000
Subject: Add helper constructors to Arc

* Two angles, wraps logic ensuring b after a
* Two vector directions
* Centre and two endpoints, in at least 2 dimensions, uses .xy()
---
 lib/maths.cpp |  5 +++++
 lib/maths.h   | 28 +++++++++-------------------
 2 files changed, 14 insertions(+), 19 deletions(-)

(limited to 'lib')

diff --git a/lib/maths.cpp b/lib/maths.cpp
index bf17204..51e27fe 100644
--- a/lib/maths.cpp
+++ b/lib/maths.cpp
@@ -4,6 +4,11 @@
 #include <glm/gtx/rotate_vector.hpp>
 #include <glm/gtx/transform.hpp>
 
+Arc::Arc(const RelativePosition2D & dir0, const RelativePosition2D & dir1) :
+	Arc {vector_yaw(dir0), vector_yaw(dir1)} { }
+
+Arc::Arc(const Angle anga, const Angle angb) : pair {anga, (angb < anga) ? angb + two_pi : angb} { }
+
 glm::mat4
 flat_orientation(const Direction3D & diff)
 {
diff --git a/lib/maths.h b/lib/maths.h
index 20a397b..656fefd 100644
--- a/lib/maths.h
+++ b/lib/maths.h
@@ -8,11 +8,16 @@
 #include <stdexcept>
 #include <utility>
 
-struct Arc : public std::pair<float, float> {
-	using std::pair<float, float>::pair;
+struct Arc : public std::pair<Angle, Angle> {
+	template<glm::length_t Lc, glm::length_t Le, typename T, glm::qualifier Q>
+		requires(Lc >= 2, Le >= 2)
+	Arc(const glm::vec<Lc, T, Q> & centre, const glm::vec<Le, T, Q> & e0p, const glm::vec<Le, T, Q> & e1p) :
+		Arc {RelativePosition2D {e0p.xy() - centre.xy()}, RelativePosition2D {e1p.xy() - centre.xy()}}
+	{
+	}
 
-	template<typename T, glm::qualifier Q>
-	Arc(const glm::vec<3, T, Q> & centre3, const glm::vec<3, T, Q> & e0p, const glm::vec<3, T, Q> & e1p);
+	Arc(const RelativePosition2D & dir0, const RelativePosition2D & dir1);
+	Arc(const Angle angb, const Angle anga);
 
 	auto
 	operator[](bool i) const
@@ -244,21 +249,6 @@ midpoint(const std::pair<T, T> & v)
 	return std::midpoint(v.first, v.second);
 }
 
-template<typename T, glm::qualifier Q>
-Arc::Arc(const glm::vec<3, T, Q> & centre3, const glm::vec<3, T, Q> & e0p, const glm::vec<3, T, Q> & e1p) :
-	Arc([&]() -> Arc {
-		const auto diffa = e0p - centre3;
-		const auto diffb = e1p - centre3;
-		const auto anga = vector_yaw(diffa);
-		const auto angb = [&diffb, &anga]() {
-			const auto angb = vector_yaw(diffb);
-			return (angb < anga) ? angb + two_pi : angb;
-		}();
-		return {anga, angb};
-	}())
-{
-}
-
 // Conversions
 template<typename T>
 inline constexpr auto
-- 
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