From ea0453f520a787dddff11d389683a255aed73ca7 Mon Sep 17 00:00:00 2001
From: Dan Goodliffe <dan@randomdan.homeip.net>
Date: Sat, 10 May 2025 12:52:50 +0100
Subject: Simplified genCurveDef for 1 direction

Uses new find_arc_centre for 1 direction which doesn't break for 180
degree solutions.
---
 lib/maths.h | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

(limited to 'lib/maths.h')

diff --git a/lib/maths.h b/lib/maths.h
index 43d6dcd..68b45da 100644
--- a/lib/maths.h
+++ b/lib/maths.h
@@ -426,6 +426,21 @@ find_arc_centre(glm::vec<2, T, Q> start, Angle entrys, glm::vec<2, T, Q> end, An
 	return find_arc_centre(start, sincos(entrys + half_pi), end, sincos(entrye - half_pi));
 }
 
+template<Arithmetic T, glm::qualifier Q = glm::defaultp>
+std::pair<glm::vec<2, T, Q>, bool>
+find_arc_centre(glm::vec<2, T, Q> start, Angle entrys, glm::vec<2, T, Q> end)
+{
+	if (start == end) {
+		return {start, false};
+	}
+	const auto startNormal = vector_normal(sincos(entrys) * 10'000.F);
+	const auto diffEnds = difference(end, start);
+	const auto midEnds = start + ((end - start) / 2);
+	const auto diffNormal = vector_normal(diffEnds);
+	const auto centre = linesIntersectAt(start, start + startNormal, midEnds, midEnds + diffNormal);
+	return {*centre, normalize(vector_yaw(diffEnds) - entrys) < 0};
+}
+
 template<Arithmetic T, glm::qualifier Q = glm::defaultp>
 Angle
 find_arcs_radius(glm::vec<2, T, Q> start, Rotation2D ad, glm::vec<2, T, Q> end, Rotation2D bd)
-- 
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