From 4b7ad201596f4cc28d240b2e9ec66c8dd1f773b0 Mon Sep 17 00:00:00 2001
From: Arthur <arthur.tang@bambulab.com>
Date: Thu, 3 Nov 2022 14:21:05 +0800
Subject: [PATCH] FIX: tree support may crash for faulty models

Root cause: overhang offset may be empty
Jira: STUDIO-1197

Change-Id: If472be8ed6d209366f118f1f0e5e14b41ce26b3c
(cherry picked from commit 663e7f29f01395bf335b6bccc91f192b64be69ae)
---
 src/libslic3r/TreeSupport.cpp | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/src/libslic3r/TreeSupport.cpp b/src/libslic3r/TreeSupport.cpp
index c55a0e8cd..01374902e 100644
--- a/src/libslic3r/TreeSupport.cpp
+++ b/src/libslic3r/TreeSupport.cpp
@@ -2055,7 +2055,9 @@ void TreeSupport::draw_circles(const std::vector<std::vector<Node*>>& contact_no
                     ExPolygon area;
                     // 如果是混合支撑里的普通部分，或没有启用顶部接触层，则直接从overhang多边形生成
                     if (node.type == ePolygon || (top_interface_layers>0 &&node.support_roof_layers_below > 0)) {
-                        area = offset_ex({ *node.overhang }, scale_(m_ts_data->m_xy_distance))[0];
+                        auto tmp = offset_ex({ *node.overhang }, scale_(m_ts_data->m_xy_distance));
+                        if(!tmp.empty()) // 对于有缺陷的模型，overhang膨胀以后可能是空的！
+                            area = tmp[0];
                     }
                     else {
                         Polygon circle;