From 2d69f6e17c56c7506520be03b0f1ea595ddd98a8 Mon Sep 17 00:00:00 2001
From: Tommaso Bianchi <tommaso.b.bianchi@gmail.com>
Date: Sat, 6 Jun 2026 16:00:37 +0200
Subject: [PATCH] belt: expose MachineFrameTransform's composed matrix

Add a const accessor for the shear*scale transform so the G-code viewer can
build the machine->model back-transform for the upright belt preview.
---
 src/libslic3r/GCode/MachineFrameTransform.hpp | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/src/libslic3r/GCode/MachineFrameTransform.hpp b/src/libslic3r/GCode/MachineFrameTransform.hpp
index 425fe3004b..f5e71398da 100644
--- a/src/libslic3r/GCode/MachineFrameTransform.hpp
+++ b/src/libslic3r/GCode/MachineFrameTransform.hpp
@@ -33,6 +33,11 @@ public:
 
     bool is_active() const { return m_active; }
 
+    // The composed shear*scale transform (identity when inactive). Exposed so the
+    // G-code viewer can build the machine->model back-transform for the upright
+    // ("designed") belt preview.
+    const Transform3d& transform() const { return m_transform; }
+
 private:
     bool        m_active    = false;
     Transform3d m_transform = Transform3d::Identity();