From 83e9f17aa817c28c03ea68db610aca59feebca44 Mon Sep 17 00:00:00 2001
From: Noisyfox <timemanager.rick@gmail.com>
Date: Thu, 7 May 2026 22:24:45 +0800
Subject: [PATCH] Fix issue that `Geometry::deg2rad()` do calculation in the
 same type as the parameter, which means if the parameter is `int` then you
 lose all the precision

---
 src/libslic3r/Geometry.hpp         | 6 +++++-
 src/libslic3r/TriangleSelector.cpp | 2 +-
 2 files changed, 6 insertions(+), 2 deletions(-)

diff --git a/src/libslic3r/Geometry.hpp b/src/libslic3r/Geometry.hpp
index 0ae7524fa0..e610a9ed4f 100644
--- a/src/libslic3r/Geometry.hpp
+++ b/src/libslic3r/Geometry.hpp
@@ -298,7 +298,11 @@ bool directions_perpendicular(double angle1, double angle2, double max_diff = 0)
 template<class T> bool contains(const std::vector<T> &vector, const Point &point);
 template<typename T> T rad2deg(T angle) { return T(180.0) * angle / T(PI); }
 double rad2deg_dir(double angle);
-template<typename T> constexpr T deg2rad(const T angle) { return T(PI) * angle / T(180.0); }
+template<typename T> constexpr T deg2rad(const T angle)
+{
+    static_assert(std::is_floating_point<T>::value, "Why do you want to calculate angle in integer?");
+    return T(PI) * angle / T(180.0);
+}
 template<typename T> T angle_to_0_2PI(T angle)
 {
     static const T TWO_PI = T(2) * T(PI);
diff --git a/src/libslic3r/TriangleSelector.cpp b/src/libslic3r/TriangleSelector.cpp
index e4d1a4521c..19f638a160 100644
--- a/src/libslic3r/TriangleSelector.cpp
+++ b/src/libslic3r/TriangleSelector.cpp
@@ -2399,7 +2399,7 @@ private:
         return line.distance(p);
     }
 };
-const double TriangleCursor::facet_angle_limit = cos(Geometry::deg2rad(5));
+const double TriangleCursor::facet_angle_limit = cos(Geometry::deg2rad(5.0));
 
 
 // Remap painting data from source mesh to target mesh using spatial mapping.