From 3f3de067f88a8eb1a575b41863e48e47c80c6692 Mon Sep 17 00:00:00 2001
From: Joseph Lenox <lenox.joseph@gmail.com>
Date: Fri, 13 Jul 2018 19:36:01 -0500
Subject: [PATCH] Added epsilon to Slic3r::Geometry; added _equiv for comparing
 two items that have operator- overloaded.

---
 src/test/test_data.hpp        | 9 +++++++--
 xs/src/libslic3r/Geometry.hpp | 4 ++++
 2 files changed, 11 insertions(+), 2 deletions(-)

diff --git a/src/test/test_data.hpp b/src/test/test_data.hpp
index de7dbcf64..9edd37629 100644
--- a/src/test/test_data.hpp
+++ b/src/test/test_data.hpp
@@ -1,6 +1,7 @@
 #ifndef SLIC3R_TEST_DATA_HPP
 #include "Point.hpp"
 #include "TriangleMesh.hpp"
+#include "Geometry.hpp"
 
 namespace Slic3r { namespace Test {
 
@@ -24,12 +25,16 @@ enum class TestMesh {
     two_hollow_squares
 };
 
-/// Port of Slic3r::Test::Mesh
-/// Basic cubes/boxes should call TriangleMesh::make_cube() directly and rescale it
+/// Port of Slic3r::Test::mesh
+/// Basic cubes/boxes should call TriangleMesh::make_cube() directly and rescale/translate it
 TriangleMesh mesh(TestMesh m);
 
 TriangleMesh mesh(TestMesh m, Pointf3 translate, Pointf3 scale = Pointf3(1.0, 1.0, 1.0));
 
+/// Templated function to see if two values are equivalent (+/- epsilon)
+template <typename T, typename U>
+bool _equiv(T a, U b) { return abs(a - b) < Slic3r::Geometry::epsilon; }
+
 } } // namespace Slic3r::Test
 
 #endif // SLIC3R_TEST_DATA_HPP
diff --git a/xs/src/libslic3r/Geometry.hpp b/xs/src/libslic3r/Geometry.hpp
index 7a4c304f4..a64fdcd5d 100644
--- a/xs/src/libslic3r/Geometry.hpp
+++ b/xs/src/libslic3r/Geometry.hpp
@@ -25,6 +25,10 @@ double rad2deg(double angle);
 double rad2deg_dir(double angle);
 double deg2rad(double angle);
 
+/// Epsilon value
+constexpr double epsilon { 1e-4 };
+constexpr coord_t scaled_epsilon { static_cast<coord_t>(epsilon / SCALING_FACTOR) };
+
 double linint(double value, double oldmin, double oldmax, double newmin, double newmax);
 bool arrange(
     // input