From 576d59f6c846cece9bace109416d2218cea09dbe Mon Sep 17 00:00:00 2001
From: "jun.zhang" <jun.zhang@bambulab.com>
Date: Mon, 17 Mar 2025 14:35:00 +0800
Subject: [PATCH] FIX: rendering issue of mirrored model

jira: STUDIO-10869

Change-Id: I985ae6fd0df917fbd4bd537220048b59df902c9a
---
 src/slic3r/GUI/3DScene.cpp | 12 +++++++++---
 1 file changed, 9 insertions(+), 3 deletions(-)

diff --git a/src/slic3r/GUI/3DScene.cpp b/src/slic3r/GUI/3DScene.cpp
index 210f7cfeb..1f50c27e4 100644
--- a/src/slic3r/GUI/3DScene.cpp
+++ b/src/slic3r/GUI/3DScene.cpp
@@ -747,9 +747,15 @@ Transform3d GLVolume::world_matrix() const
 
 bool GLVolume::is_left_handed() const
 {
-    const Vec3d &m1 = m_instance_transformation.get_mirror();
-    const Vec3d &m2 = m_volume_transformation.get_mirror();
-    return m1.x() * m1.y() * m1.z() * m2.x() * m2.y() * m2.z() < 0.;
+    // reference <Real-Time Rendering Fourth Edition> page 84
+    // link: https://www.realtimerendering.com/
+    const auto model_matrix = world_matrix().matrix();
+    Eigen::Matrix3d subMatrix = model_matrix.block<3, 3>(0, 0);
+    const auto det = subMatrix.determinant();
+    if (det < 1e-6f) {
+        return true;
+    }
+    return false;
 }
 
 const BoundingBoxf3& GLVolume::transformed_bounding_box() const