FIX: fix hybrid tree support may go outside plate

1. fix hybrid tree support may go outside plate
github: #4769
2. fix false alarm of empty layer warning
jira: STUDIO-8178

Change-Id: I7bcc3959b06184901cbec946e8840c7a94bc1cab
(cherry picked from commit 647bd4213c363eff6258992f5f607c1f03cbc482)

src/libslic3r/GCode.cpp

@@ -1202,14 +1202,23 @@ std::vector<GCode::LayerToPrint> GCode::collect_layers_to_print(const PrintObjec
             // Allow empty support layers, as the support generator may produce no extrusions for non-empty support regions.
             || (layer_to_print.support_layer /* && layer_to_print.support_layer->has_extrusions() */)) {
             double top_cd = object.config().support_top_z_distance;
-            double bottom_cd = object.config().support_bottom_z_distance;
-
+            double bottom_cd = object.config().support_bottom_z_distance == 0. ? top_cd : object.config().support_bottom_z_distance;
+            //if (!object.print()->config().independent_support_layer_height)
+            { // the actual support gap may be larger than the configured one due to rounding to layer height for organic support, regardless of independent support layer height
+                top_cd    = std::ceil(top_cd / object.config().layer_height) * object.config().layer_height;
+                bottom_cd = std::ceil(bottom_cd / object.config().layer_height) * object.config().layer_height;
+            }
             double extra_gap = (layer_to_print.support_layer ? bottom_cd : top_cd);
 
             // raft contact distance should not trigger any warning
-            if(last_extrusion_layer && last_extrusion_layer->support_layer)
+            if (last_extrusion_layer && last_extrusion_layer->support_layer) {
+                double raft_gap = object.config().raft_contact_distance.value;
+                //if (!object.print()->config().independent_support_layer_height)
+                {
+                    raft_gap = std::ceil(raft_gap / object.config().layer_height) * object.config().layer_height;
+                }
                 extra_gap = std::max(extra_gap, object.config().raft_contact_distance.value);
-
+            }
             double maximal_print_z = (last_extrusion_layer ? last_extrusion_layer->print_z() : 0.)
                 + layer_to_print.layer()->height
                 + std::max(0., extra_gap);

src/libslic3r/Support/TreeSupport.cpp

@@ -1662,6 +1662,9 @@ void TreeSupport::generate()
     create_tree_support_layers();
     m_ts_data = m_object->alloc_tree_support_preview_cache();
     m_ts_data->is_slim = is_slim;
+    // // get the ring of outside plate
+    // auto tmp= diff_ex(offset_ex(m_machine_border, scale_(100)), m_machine_border);
+    // if (!tmp.empty()) m_ts_data->m_machine_border = tmp[0];
 
     std::vector<TreeSupport3D::SupportElements> move_bounds(m_highest_overhang_layer + 1);
     profiler.stage_start(STAGE_GENERATE_CONTACT_NODES);
@@ -2093,6 +2096,7 @@ void TreeSupport::draw_circles()
 
                 // join roof segments
                 roof_areas     = diff_clipped(offset2_ex(roof_areas, line_width_scaled, -line_width_scaled), get_collision(false));
+                roof_areas     = intersection_ex(roof_areas, m_machine_border);
                 roof_1st_layer = diff_clipped(offset2_ex(roof_1st_layer, line_width_scaled, -line_width_scaled), get_collision(false));
 
                 // roof_1st_layer and roof_areas may intersect, so need to subtract roof_areas from roof_1st_layer
@@ -3460,6 +3464,7 @@ const ExPolygons& TreeSupportData::calculate_collision(const RadiusLayerPair& ke
 
     ExPolygons collision_areas = offset_ex(m_layer_outlines[key.layer_nr], scale_(key.radius+m_xy_distance));
     collision_areas = expolygons_simplify(collision_areas, scale_(m_radius_sample_resolution));
+    // collision_areas.emplace_back(m_machine_border);
     const auto ret = m_collision_cache.insert({ key, std::move(collision_areas) });
     return ret.first->second;
 }

src/libslic3r/Support/TreeSupport.hpp

@@ -251,6 +251,7 @@ public:
     std::vector<LayerHeightData> layer_heights;
 
     std::vector<SupportNode*> contact_nodes;
+    // ExPolygon                  m_machine_border;
 
 private:
     /*!