From 5cba1e83199c017e07b22abca96d774c44f0a571 Mon Sep 17 00:00:00 2001
From: Vojtech Bubnik <bubnikv@gmail.com>
Date: Mon, 10 Oct 2022 14:14:55 +0200
Subject: [PATCH] Improved Point.hpp to_2d() and to_3d() templates to accept
 Eigen expressions

---
 src/libslic3r/Point.hpp | 14 ++++++++++----
 1 file changed, 10 insertions(+), 4 deletions(-)

diff --git a/src/libslic3r/Point.hpp b/src/libslic3r/Point.hpp
index da558e438..949ddbad1 100644
--- a/src/libslic3r/Point.hpp
+++ b/src/libslic3r/Point.hpp
@@ -111,11 +111,17 @@ inline double angle(const Eigen::MatrixBase<Derived> &v1, const Eigen::MatrixBas
     return atan2(cross2(v1d, v2d), v1d.dot(v2d));
 }
 
-template<class T, int N, int Options>
-Eigen::Matrix<T, 2, 1, Eigen::DontAlign> to_2d(const Eigen::MatrixBase<Eigen::Matrix<T, N, 1, Options>> &ptN) { return { ptN.x(), ptN.y() }; }
+template<typename Derived>
+Eigen::Matrix<typename Derived::Scalar, 2, 1, Eigen::DontAlign> to_2d(const Eigen::MatrixBase<Derived> &ptN) {
+    static_assert(Derived::IsVectorAtCompileTime && int(Derived::SizeAtCompileTime) >= 3, "to_2d(): first parameter is not a 3D or higher dimensional vector");
+    return { ptN.x(), ptN.y() };
+}
 
-template<class T, int Options>
-Eigen::Matrix<T, 3, 1, Eigen::DontAlign> to_3d(const Eigen::MatrixBase<Eigen::Matrix<T, 2, 1, Options>> & pt, const T z) { return { pt.x(), pt.y(), z }; }
+template<typename Derived>
+inline Eigen::Matrix<typename Derived::Scalar, 3, 1, Eigen::DontAlign> to_3d(const Eigen::MatrixBase<Derived> &pt, const typename Derived::Scalar z) {
+    static_assert(Derived::IsVectorAtCompileTime && int(Derived::SizeAtCompileTime) == 2, "to_3d(): first parameter is not a 2D vector");
+    return { pt.x(), pt.y(), z };
+}
 
 inline Vec2d   unscale(coord_t x, coord_t y) { return Vec2d(unscale<double>(x), unscale<double>(y)); }
 inline Vec2d   unscale(const Vec2crd &pt) { return Vec2d(unscale<double>(pt.x()), unscale<double>(pt.y())); }