Hopefully a fix of https://github.com/prusa3d/Slic3r/issues/11

Replaced eval { die } construct with a bool return value indicating
success or failure of an automatic arrangement of parts on the print bed.

Don't know exactly what is happening here, but throwing a "die" inside
a XS function and then catching it inside an eval {} block is suspcious.

lib/Slic3r/GUI/Plater.pm

@@ -965,9 +965,7 @@ sub arrange {
     $self->pause_background_process;
     
     my $bb = Slic3r::Geometry::BoundingBoxf->new_from_points($self->{config}->bed_shape);
-    eval {
-        $self->{model}->arrange_objects($self->GetFrame->config->min_object_distance, $bb);
-    };
+    my $success = $self->{model}->arrange_objects($self->GetFrame->config->min_object_distance, $bb);
     # ignore arrange failures on purpose: user has visual feedback and we don't need to warn him
     # when parts don't fit in print bed
     

xs/src/libslic3r/Geometry.cpp

@@ -424,9 +424,12 @@ class ArrangeItemIndex {
     ArrangeItem item;
     ArrangeItemIndex(coordf_t _index, ArrangeItem _item) : index(_index), item(_item) {};
 };
-Pointfs
-arrange(size_t total_parts, const Pointf &part_size, coordf_t dist, const BoundingBoxf* bb)
+
+bool
+arrange(size_t total_parts, const Pointf &part_size, coordf_t dist, const BoundingBoxf* bb, Pointfs &positions)
 {
+    positions.clear();
+
     Pointf part = part_size;
 
     // use actual part size (the largest) plus separation distance (half on each side) in spacing algorithm
@@ -446,7 +449,7 @@ arrange(size_t total_parts, const Pointf &part_size, coordf_t dist, const Boundi
     size_t cellw = floor((area.x + dist) / part.x);
     size_t cellh = floor((area.y + dist) / part.y);
     if (total_parts > (cellw * cellh))
-        CONFESS(PRINTF_ZU " parts won't fit in your print area!\n", total_parts);
+        return false;
     
     // total space used by cells
     Pointf cells(cellw * part.x, cellh * part.y);
@@ -527,7 +530,6 @@ arrange(size_t total_parts, const Pointf &part_size, coordf_t dist, const Boundi
         }
     }
     // now we actually place objects into cells, positioned such that the left and bottom borders are at 0
-    Pointfs positions;
     for (size_t i = 1; i <= total_parts; ++i) {
         ArrangeItemIndex c = cellsorder.front();
         cellsorder.erase(cellsorder.begin());
@@ -544,7 +546,7 @@ arrange(size_t total_parts, const Pointf &part_size, coordf_t dist, const Boundi
         }
     }
     
-    return positions;
+    return true;
 }
 #endif
 

xs/src/libslic3r/Geometry.hpp

@@ -26,7 +26,11 @@ double deg2rad(double angle);
 void simplify_polygons(const Polygons &polygons, double tolerance, Polygons* retval);
 
 double linint(double value, double oldmin, double oldmax, double newmin, double newmax);
-Pointfs arrange(size_t num_parts, const Pointf &part_size, coordf_t gap, const BoundingBoxf* bed_bounding_box);
+bool arrange(
+    // input
+    size_t num_parts, const Pointf &part_size, coordf_t gap, const BoundingBoxf* bed_bounding_box, 
+    // output
+    Pointfs &positions);
 
 class MedialAxis {
     public:

xs/src/libslic3r/Model.cpp

@@ -215,21 +215,22 @@ Model::raw_mesh() const
     return mesh;
 }
 
-Pointfs
-Model::_arrange(const Pointfs &sizes, coordf_t dist, const BoundingBoxf* bb) const
+bool
+Model::_arrange(const Pointfs &sizes, coordf_t dist, const BoundingBoxf* bb, Pointfs &out) const
 {
     // we supply unscaled data to arrange()
     return Slic3r::Geometry::arrange(
         sizes.size(),               // number of parts
         BoundingBoxf(sizes).max,    // width and height of a single cell
         dist,                       // distance between cells
-        bb                          // bounding box of the area to fill
+        bb,                         // bounding box of the area to fill
+        out                         // output positions
     );
 }
 
 /*  arrange objects preserving their instance count
     but altering their instance positions */
-void
+bool
 Model::arrange_objects(coordf_t dist, const BoundingBoxf* bb)
 {
     // get the (transformed) size of each instance so that we take
@@ -241,7 +242,9 @@ Model::arrange_objects(coordf_t dist, const BoundingBoxf* bb)
         }
     }
     
-    Pointfs positions = this->_arrange(instance_sizes, dist, bb);
+    Pointfs positions;
+    if (! this->_arrange(instance_sizes, dist, bb, positions))
+        return false;
     
     for (ModelObjectPtrs::const_iterator o = this->objects.begin(); o != this->objects.end(); ++o) {
         for (ModelInstancePtrs::const_iterator i = (*o)->instances.begin(); i != (*o)->instances.end(); ++i) {
@@ -250,6 +253,7 @@ Model::arrange_objects(coordf_t dist, const BoundingBoxf* bb)
         }
         (*o)->invalidate_bounding_box();
     }
+    return true;
 }
 
 /*  duplicate the entire model preserving instance relative positions */
@@ -257,7 +261,9 @@ void
 Model::duplicate(size_t copies_num, coordf_t dist, const BoundingBoxf* bb)
 {
     Pointfs model_sizes(copies_num-1, this->bounding_box().size());
-    Pointfs positions = this->_arrange(model_sizes, dist, bb);
+    Pointfs positions;
+    if (! this->_arrange(model_sizes, dist, bb, positions))
+        CONFESS("Cannot duplicate part as the resulting objects would not fit on the print bed.\n");
     
     // note that this will leave the object count unaltered
     

xs/src/libslic3r/Model.hpp

@@ -64,8 +64,9 @@ public:
     void translate(coordf_t x, coordf_t y, coordf_t z);
     TriangleMesh mesh() const;
     TriangleMesh raw_mesh() const;
-    Pointfs _arrange(const Pointfs &sizes, coordf_t dist, const BoundingBoxf* bb = NULL) const;
-    void arrange_objects(coordf_t dist, const BoundingBoxf* bb = NULL);
+    bool _arrange(const Pointfs &sizes, coordf_t dist, const BoundingBoxf* bb, Pointfs &out) const;
+    bool arrange_objects(coordf_t dist, const BoundingBoxf* bb = NULL);
+    // Croaks if the duplicated objects do not fit the print bed.
     void duplicate(size_t copies_num, coordf_t dist, const BoundingBoxf* bb = NULL);
     void duplicate_objects(size_t copies_num, coordf_t dist, const BoundingBoxf* bb = NULL);
     void duplicate_objects_grid(size_t x, size_t y, coordf_t dist);

xs/xsp/Geometry.xsp

@@ -9,7 +9,12 @@
 %package{Slic3r::Geometry};
 
 Pointfs arrange(size_t total_parts, Pointf* part, coordf_t dist, BoundingBoxf* bb = NULL)
-    %code{% RETVAL = Slic3r::Geometry::arrange(total_parts, *part, dist, bb); %};
+    %code{% 
+        Pointfs points;
+        if (! Slic3r::Geometry::arrange(total_parts, *part, dist, bb, points))
+            CONFESS(PRINTF_ZU " parts won't fit in your print area!\n", total_parts);
+        RETVAL = points;
+    %};
 
 %{
 

xs/xsp/Model.xsp

@@ -66,8 +66,7 @@
     ModelObjectPtrs* objects()
         %code%{ RETVAL = &THIS->objects; %};
     
-    Pointfs _arrange(Pointfs sizes, double dist, BoundingBoxf* bb = NULL);
-    void arrange_objects(double dist, BoundingBoxf* bb = NULL);
+    bool arrange_objects(double dist, BoundingBoxf* bb = NULL);
     void duplicate(unsigned int copies_num, double dist, BoundingBoxf* bb = NULL);
     void duplicate_objects(unsigned int copies_num, double dist, BoundingBoxf* bb = NULL);
     void duplicate_objects_grid(unsigned int x, unsigned int y, double dist);