From 663df48a95946cb3ecdcc68dd7179ae7d936c028 Mon Sep 17 00:00:00 2001
From: Arthur <arthur.tang@bambulab.com>
Date: Wed, 17 Aug 2022 10:11:38 +0800
Subject: [PATCH] FIX: cut_to_parts+keep_lower crashes

Change-Id: I65eb51952a2062e6726e12e6cdb42f09f7816bc3
(cherry picked from commit cf9873717c756ddfe7e584ccb74f29763f529883)
---
 src/libslic3r/Model.cpp | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/libslic3r/Model.cpp b/src/libslic3r/Model.cpp
index 5f9c8c1cb..888edd6c2 100644
--- a/src/libslic3r/Model.cpp
+++ b/src/libslic3r/Model.cpp
@@ -1538,7 +1538,7 @@ ModelObjectPtrs ModelObject::cut(size_t instance, std::array<Vec3d, 4> plane_poi
     bool keep_lower = attributes.has(ModelObjectCutAttribute::KeepLower);
     bool cut_to_parts = attributes.has(ModelObjectCutAttribute::CutToParts);
     ModelObject* upper = keep_upper ? ModelObject::new_clone(*this) : nullptr;
-    ModelObject* lower = cut_to_parts ? upper : (keep_lower ? ModelObject::new_clone(*this) : nullptr);
+    ModelObject* lower = (cut_to_parts&&upper!=nullptr) ? upper : (keep_lower ? ModelObject::new_clone(*this) : nullptr);
 
     if (attributes.has(ModelObjectCutAttribute::KeepUpper)) {
         upper->set_model(nullptr);