Fix crash when exporting to stl

src/libslic3r/CSGMesh/CSGMesh.hpp

@@ -1,8 +1,10 @@
 #ifndef CSGMESH_HPP
 #define CSGMESH_HPP
 
+#include "libslic3r/Point.hpp"
+
 #include <libslic3r/AnyPtr.hpp>
-#include <admesh/stl.h>
+#include <libslic3r/TriangleMesh.hpp>
 
 namespace Slic3r { namespace csg {
 
@@ -81,6 +83,35 @@ struct CSGPart {
     {}
 };
 
+template<class Cont> bool is_all_positive(const Cont &csgmesh)
+{
+    bool is_all_pos =
+        std::all_of(csgmesh.begin(),
+                    csgmesh.end(),
+                    [](auto &part) {
+                        return csg::get_operation(part) == csg::CSGType::Union;
+                    });
+
+    return is_all_pos;
+}
+
+template<class Cont>
+indexed_triangle_set csgmesh_merge_positive_parts(const Cont &csgmesh)
+{
+    indexed_triangle_set m;
+    for (auto &csgpart : csgmesh) {
+        auto op = csg::get_operation(csgpart);
+        const indexed_triangle_set * pmesh = csg::get_mesh(csgpart);
+        if (pmesh && op == csg::CSGType::Union) {
+            indexed_triangle_set mcpy = *pmesh;
+            its_transform(mcpy, csg::get_transform(csgpart), true);
+            its_merge(m, mcpy);
+        }
+    }
+
+    return m;
+}
+
 }} // namespace Slic3r::csg
 
 #endif // CSGMESH_HPP

src/libslic3r/SLAPrintSteps.cpp

@@ -127,35 +127,6 @@ void SLAPrint::Steps::apply_printer_corrections(SLAPrintObject &po, SliceOrigin
     }
 }
 
-template<class Cont> bool is_all_positive(const Cont &csgmesh)
-{
-    bool is_all_pos =
-        std::all_of(csgmesh.begin(),
-                    csgmesh.end(),
-                    [](auto &part) {
-                        return csg::get_operation(part) == csg::CSGType::Union;
-                    });
-
-    return is_all_pos;
-}
-
-template<class Cont>
-static indexed_triangle_set csgmesh_merge_positive_parts(const Cont &csgmesh)
-{
-    indexed_triangle_set m;
-    for (auto &csgpart : csgmesh) {
-        auto op = csg::get_operation(csgpart);
-        const indexed_triangle_set * pmesh = csg::get_mesh(csgpart);
-        if (pmesh && op == csg::CSGType::Union) {
-            indexed_triangle_set mcpy = *pmesh;
-            its_transform(mcpy, csg::get_transform(csgpart), true);
-            its_merge(m, mcpy);
-        }
-    }
-
-    return m;
-}
-
 indexed_triangle_set SLAPrint::Steps::generate_preview_vdb(
     SLAPrintObject &po, SLAPrintObjectStep step)
 {

src/slic3r/GUI/Plater.cpp

@@ -6471,9 +6471,12 @@ void Plater::export_stl_obj(bool extended, bool selection_only)
         csg::model_to_csgmesh(mo, Transform3d::Identity(), std::back_inserter(csgmesh),
                               csg::mpartsPositive | csg::mpartsNegative | csg::mpartsDoSplits);
 
-        if (csg::check_csgmesh_booleans(range(csgmesh)) == csgmesh.end()) {
+        auto csgrange = range(csgmesh);
+        if (csg::is_all_positive(csgrange)) {
+            mesh = TriangleMesh{csg::csgmesh_merge_positive_parts(csgrange)};
+        } else if (csg::check_csgmesh_booleans(csgrange) == csgrange.end()) {
             try {
-                auto cgalm = csg::perform_csgmesh_booleans(range(csgmesh));
+                auto cgalm = csg::perform_csgmesh_booleans(csgrange);
                 mesh = MeshBoolean::cgal::cgal_to_triangle_mesh(*cgalm);
             } catch (...) {}
         }