From 41b1dc3d80d43f4a2df141edd3d4b5bd1ee24ce1 Mon Sep 17 00:00:00 2001
From: Lukas Matena <lukasmatena@seznam.cz>
Date: Thu, 6 Aug 2020 14:05:42 +0200
Subject: [PATCH] Fix of custom supports 3MF loading Multiple-part objects were
 not handled correctly

---
 src/libslic3r/Format/3mf.cpp | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/src/libslic3r/Format/3mf.cpp b/src/libslic3r/Format/3mf.cpp
index 3612e6898..59dc85a0a 100644
--- a/src/libslic3r/Format/3mf.cpp
+++ b/src/libslic3r/Format/3mf.cpp
@@ -1878,10 +1878,11 @@ namespace Slic3r {
             volume->calculate_convex_hull();
 
             // recreate custom supports from previously loaded attribute
-            assert(geometry.custom_supports.size() == triangles_count);
             for (unsigned i=0; i<triangles_count; ++i) {
-                if (! geometry.custom_supports[i].empty())
-                    volume->m_supported_facets.set_triangle_from_string(i, geometry.custom_supports[i]);
+                size_t index = src_start_id/3 + i;
+                assert(index < geometry.custom_supports.size());
+                if (! geometry.custom_supports[index].empty())
+                    volume->m_supported_facets.set_triangle_from_string(i, geometry.custom_supports[index]);
             }
 
             // apply the remaining volume's metadata