Precise Seam: new full-coverage policy for Seam Blocked (#16170)

* Precise Seam: new full-coverage policy for Seam Blocked

A Seam Blocked modifier that covers a whole perimeter now blocks it, like a
perimeter painted red all round, instead of being skipped. It overrides
painting and lower-priority modifiers, like Enforced and Neutral. A new
warning names the modifier: "Seam Blocked modifier "<name>" of "<object>"
covers an entire perimeter". It is shown only when a perimeter stays
entirely Blocked after all weak modifiers. The full-containment warning now
covers only Center, Left and Right.

* Precise Seam: fix seams on perimeters blocked all round

- SeamComparator::is_first_not_much_worse() compares the types first, so two
  Blocked candidates fall through like Neutral ones. On a perimeter blocked
  all round, by a whole Seam Blocked modifier or by red painting, Random put
  the seam on the closing vertex of every layer and Aligned stopped aligning.
- The whole-perimeter Blocked warning flags only the highest whole zone, the
  one in effect. A lower whole zone it overwrites is no longer reported, and
  the candidate scan runs only when that zone is Blocked.
- The warning msgids take the type name from the menu's "Seam Blocked" msgid.
- PreciseSeamWarnings::set() shares the load-before-store idiom, and every
  weak segment records its modifier.
- Tests: a whole Blocked perimeter gets the seams of an unmarked one under
  every seam position; overwritten whole Blocked zones are not reported.

---------

Co-authored-by: Ian Bassi <ian.bassi@outlook.com>

src/libslic3r/GCode/PreciseSeam.cpp

@@ -673,7 +673,7 @@ static void refine_at_vertex(
     }
 }
 
-// Records one extraction for the warnings: the type of a modifier with a discarded fragment, and the
+// Records one extraction for the warnings: the type of a modifier with a discarded fragment, the
 // evaluated/reached flags for "had no effect" (a discarded fragment counts as reached, a contact not).
 static void record_extraction(PreciseSeamWarnings *warnings, const ModelVolume *modifier,
                               const SegmentExtraction &extracted)
@@ -685,13 +685,10 @@ static void record_extraction(PreciseSeamWarnings *warnings, const ModelVolume *
     const auto it = warnings->modifier_usage.find(modifier);
     if (it == warnings->modifier_usage.end())
         return;
-    // Load before store: most calls find the flag already set, so shared cache lines stay clean.
     PreciseSeamWarnings::ModifierUsage &usage = it->second;
-    if (!usage.checked.load(std::memory_order_relaxed))
-        usage.checked.store(true, std::memory_order_relaxed);
-    const bool reached = !extracted.segments.empty() || extracted.full_containment || extracted.discarded_fragments > 0;
-    if (reached && !usage.reached.load(std::memory_order_relaxed))
-        usage.reached.store(true, std::memory_order_relaxed);
+    PreciseSeamWarnings::set(usage.checked);
+    if (!extracted.segments.empty() || extracted.full_containment || extracted.discarded_fragments > 0)
+        PreciseSeamWarnings::set(usage.reached);
 }
 
 // Strong priority is per modifier, never a global maximum across different modifiers.
@@ -953,22 +950,15 @@ std::vector<WeakModifierSegment> collect_weak_modifier_segments(
         const SegmentExtraction extracted = extract_perimeter_segments(prepared, it->second[layer_id], modifier_volume->type(), context);
         record_extraction(warnings, modifier_volume, extracted);
         const auto type = convert_weak_modifier_type(modifier_volume->type());
-        // Full containment works like seam painting: Enforced and Neutral type the whole perimeter;
-        // Blocked is skipped with a warning, since the seam cannot avoid the whole perimeter.
+        // Full containment works like seam painting all round: the whole perimeter takes the type.
+        // A perimeter left whole Blocked also gets a warning (see apply_weak_modifiers_to_perimeter()).
         if (extracted.full_containment) {
-            if (type == EnforcedBlockedSeamPoint::Blocked) {
-                if (warnings)
-                    PreciseSeamWarnings::mark(warnings->full_containment, modifier_volume->type());
-                continue;
-            }
-            WeakModifierSegment whole{type, Point(), PerimeterPosition{0, 0.}, Point(), PerimeterPosition{0, 0.}};
-            whole.whole_perimeter = true;
-            result.push_back(whole);
+            result.push_back({type, Point(), PerimeterPosition{0, 0.}, Point(), PerimeterPosition{0, 0.}, true, modifier_volume});
             continue;
         }
         for (const PerimeterSegment &segment : extracted.segments) {
             result.push_back({type, segment.polyline.points.front(), segment.begin,
-                                   segment.polyline.points.back(), segment.end});
+                                   segment.polyline.points.back(), segment.end, false, modifier_volume});
         }
     }
     // Boundary insertion, refinement and last-write-wins priority use the established path.
@@ -979,7 +969,8 @@ void apply_weak_modifiers_to_perimeter(
     const std::vector<WeakModifierSegment> &weak_segments,
     PrintObjectSeamData::LayerSeams &result,
     const SeamPlacerImpl::Perimeter &perimeter,
-    bool &some_point_enforced)
+    bool &some_point_enforced,
+    PreciseSeamWarnings *warnings)
 {
     // Get z-coordinate for unscaling boundary points
     const float z_coord = result.points[perimeter.start_index].position.z();
@@ -1029,6 +1020,19 @@ void apply_weak_modifiers_to_perimeter(
             some_point_enforced = true;
         }
     }
+
+    // Only the highest whole zone is in effect, and a higher band may still unblock part of it.
+    if (warnings == nullptr)
+        return;
+    const auto last_whole = std::find_if(weak_segments.rbegin(), weak_segments.rend(),
+                                         [](const WeakModifierSegment &segment) { return segment.whole_perimeter; });
+    if (last_whole == weak_segments.rend() || last_whole->type != EnforcedBlockedSeamPoint::Blocked)
+        return;
+    for (size_t i = perimeter.start_index; i < perimeter.end_index; ++i)
+        if (result.points[i].type != EnforcedBlockedSeamPoint::Blocked)
+            return;
+    if (const auto usage = warnings->modifier_usage.find(last_whole->modifier); usage != warnings->modifier_usage.end())
+        PreciseSeamWarnings::set(usage->second.fully_blocked);
 }
 
 // Restore precise seam positions that may have been modified

src/libslic3r/GCode/PreciseSeam.hpp

@@ -49,18 +49,20 @@ struct PreciseSeamWarnings {
     // Masks of the Precise Seam types that caused each warning reason, one bit per type (type_bit()).
     // The user warning lists the types instead of naming modifiers.
     std::atomic<unsigned> multiple_intersections{0}; // Center/Left/Right with several segments on a perimeter.
-    std::atomic<unsigned> full_containment{0};       // Skipped for a perimeter fully inside: Center/Left/Right, Blocked.
+    std::atomic<unsigned> full_containment{0};       // Skipped for a perimeter fully inside: Center/Left/Right.
     std::atomic<unsigned> failed_types{0};           // Types with at least one discarded fragment.
     std::atomic<size_t> failed_fragments{0}; // Total discarded fragments, for the log summary.
     // Fragments saved by the rare-case fallback or accepted as contacts; log only, no user warning.
     // Clipper is deterministic, so a prismatic model can repeat the same case on every layer.
     std::atomic<size_t> recovered_fragments{0};
 
-    // Per-modifier flags for the "had no effect" warning. Modifiers are registered before the parallel
-    // phase, so workers only set flags; unregistered ones (e.g. in tests) are not tracked.
+    // Per-modifier flags for the "had no effect" and "covers an entire perimeter" warnings. Modifiers are
+    // registered before the parallel phase, so workers only set flags; unregistered ones (e.g. in tests)
+    // are not tracked.
     struct ModifierUsage {
-        std::atomic<bool> checked{false}; // Extracted on at least one perimeter.
-        std::atomic<bool> reached{false}; // Gave a segment, full containment or a discarded fragment.
+        std::atomic<bool> checked{false};       // Extracted on at least one perimeter.
+        std::atomic<bool> reached{false};       // Gave a segment, full containment or a discarded fragment.
+        std::atomic<bool> fully_blocked{false}; // Seam Blocked whole zone in effect on a perimeter left Blocked.
     };
     std::unordered_map<const ModelVolume*, ModifierUsage> modifier_usage;
 
@@ -70,13 +72,18 @@ struct PreciseSeamWarnings {
         assert(is_precise_seam(type));
         return 1u << (int(type) - int(ModelVolumeType::PRECISE_SEAM_CENTER));
     }
-    // Load before fetch_or: most calls find the bit already set, so shared cache lines stay clean.
+    // Load before writing: most calls find the bit or flag already set, so shared cache lines stay clean.
     static void mark(std::atomic<unsigned> &mask, ModelVolumeType type)
     {
         const unsigned bit = type_bit(type);
         if ((mask.load(std::memory_order_relaxed) & bit) == 0)
             mask.fetch_or(bit, std::memory_order_relaxed);
     }
+    static void set(std::atomic<bool> &flag)
+    {
+        if (!flag.load(std::memory_order_relaxed))
+            flag.store(true, std::memory_order_relaxed);
+    }
 };
 
 // Optional caller identity for concise diagnostics when an intersection is discarded.
@@ -139,9 +146,10 @@ struct WeakModifierSegment {
     PerimeterPosition left_position; // Position on the source perimeter before insertion/refinement.
     Point right_point;              // Coordinates of right (last) point of segment
     PerimeterPosition right_position; // Retained provenance, not an index into the modified polygon.
-    // Full containment of an Enforced or Neutral modifier: the zone is the whole perimeter, without
-    // boundaries (the points and positions above are unused and nothing is inserted for it).
+    // Full containment of a weak modifier: the zone is the whole perimeter, without boundaries
+    // (the points and positions above are unused and nothing is inserted for it).
     bool whole_perimeter = false;
+    const ModelVolume *modifier = nullptr; // Source modifier, for the warnings.
 };
 
 // Collects the object's Precise Seam volumes: strong ones in priority order, weak ones in application
@@ -173,12 +181,14 @@ std::vector<WeakModifierSegment> collect_weak_modifier_segments(
     PreciseSeamWarnings* warnings = nullptr);
 
 // Retypes the candidates inside each zone in the given order (pass zones lowest priority first);
-// sets some_point_enforced when an Enforced zone applies.
+// sets some_point_enforced when an Enforced zone applies. When the whole perimeter ends up Blocked and
+// the highest whole-perimeter zone is Blocked, flags that zone's modifier for the warning.
 void apply_weak_modifiers_to_perimeter(
     const std::vector<WeakModifierSegment> &weak_segments,
     PrintObjectSeamData::LayerSeams &result,
     const SeamPlacerImpl::Perimeter &perimeter,
-    bool &some_point_enforced);
+    bool &some_point_enforced,
+    PreciseSeamWarnings *warnings = nullptr);
 
 // Restore precise seam positions that may have been modified by alignment
 // Iterates through all perimeters and restores precise_seam_point positions

src/libslic3r/GCode/SeamPlacer.cpp

@@ -608,7 +608,7 @@ void process_perimeter_polygon(const Polygon &orig_polygon, float z_coord, const
   // Apply weak modifiers if no strong modifier was inserted
   if (!inserted_seam_position.has_value() && !weak_segments.empty()) {
     PreciseSeam::apply_weak_modifiers_to_perimeter(
-        weak_segments, result, perimeter, some_point_enforced);
+        weak_segments, result, perimeter, some_point_enforced, warnings);
   }
 
   if (some_point_enforced) {
@@ -896,18 +896,15 @@ struct SeamComparator {
       return a.central_enforcer;
     }
 
-    if (a.type == EnforcedBlockedSeamPoint::Enforced) {
-      return true;
-    }
-
-    if (a.type == EnforcedBlockedSeamPoint::Blocked) {
-      return false;
-    }
-
     if (a.type != b.type) {
       return a.type > b.type;
     }
 
+    // Two Blocked points fall through like Neutral ones, so a perimeter blocked all round still gets a proper seam.
+    if (a.type == EnforcedBlockedSeamPoint::Enforced) {
+      return true;
+    }
+
     //avoid overhangs
     if ((a.overhang > 0.0f || b.overhang > 0.0f)
         && abs(a.overhang - b.overhang) > (0.1f * a.perimeter.flow_width)) {
@@ -1660,18 +1657,42 @@ void SeamPlacer::init(const Print &print, std::function<void(void)> throw_if_can
           parts.push_back((boost::format(_u8L("multiple intersections with a perimeter, only one was used (%1%)")) % type_list(mi)).str());
       if (fc != 0)
           parts.push_back((boost::format(_u8L("a perimeter is fully inside a modifier, the modifier was not applied to it (%1%)")) % type_list(fc)).str());
-      // Modifiers evaluated somewhere that never reached a perimeter; never-evaluated ones are not reported.
-      // Print and volume order make the named one deterministic; the log lists them all.
-      std::vector<const ModelVolume*> no_effect;
-      for (const PrintObject *po : print.objects())
-          for (const ModelVolume *volume : po->model_object()->volumes) {
-              const auto it = precise_seam_warnings.modifier_usage.find(volume);
-              if (it != precise_seam_warnings.modifier_usage.end() &&
-                  it->second.checked.load(std::memory_order_relaxed) &&
-                  !it->second.reached.load(std::memory_order_relaxed) &&
-                  std::find(no_effect.begin(), no_effect.end(), volume) == no_effect.end())
-                  no_effect.push_back(volume);
+      // Modifiers whose usage flags match, in print and volume order, so the named one is deterministic.
+      const auto collect_modifiers = [&print, &precise_seam_warnings](const auto &matches) {
+          std::vector<const ModelVolume*> found;
+          for (const PrintObject *po : print.objects())
+              for (const ModelVolume *volume : po->model_object()->volumes) {
+                  const auto it = precise_seam_warnings.modifier_usage.find(volume);
+                  if (it != precise_seam_warnings.modifier_usage.end() && matches(it->second) &&
+                      std::find(found.begin(), found.end(), volume) == found.end())
+                      found.push_back(volume);
+              }
+          return found;
+      };
+      // Seam Blocked modifiers whose whole perimeter stayed Blocked; the user warning names only the
+      // first one, the log lists them all.
+      const std::vector<const ModelVolume*> fully_blocked = collect_modifiers(
+          [](const PreciseSeam::PreciseSeamWarnings::ModifierUsage &usage) { return usage.fully_blocked.load(std::memory_order_relaxed); });
+      for (const ModelVolume *volume : fully_blocked)
+          BOOST_LOG_TRIVIAL(warning) << "[PreciseSeamFullyBlocked] object=\"" << volume->get_object()->name
+              << "\" modifier=\"" << volume->name << "\"";
+      if (!fully_blocked.empty()) {
+          const ModelVolume *first = fully_blocked.front();
+          if (fully_blocked.size() == 1) {
+              // TRN: %1% is the modifier type "Seam Blocked" as in the menu, %2% the modifier name, %3% the object name.
+              parts.push_back((boost::format(_u8L("%1% modifier \"%2%\" of \"%3%\" covers an entire perimeter"))
+                  % _u8L("Seam Blocked") % first->name % first->get_object()->name).str());
+          } else {
+              // TRN: %1% is the modifier type "Seam Blocked" as in the menu, %2% the modifier name, %3% the object name, %4% the number of modifiers.
+              parts.push_back((boost::format(_u8L("%1% modifier \"%2%\" of \"%3%\" (%4% in total) covers an entire perimeter"))
+                  % _u8L("Seam Blocked") % first->name % first->get_object()->name % fully_blocked.size()).str());
           }
+      }
+      // Modifiers evaluated somewhere that never reached a perimeter; never-evaluated ones are not reported.
+      const std::vector<const ModelVolume*> no_effect = collect_modifiers(
+          [](const PreciseSeam::PreciseSeamWarnings::ModifierUsage &usage) {
+              return usage.checked.load(std::memory_order_relaxed) && !usage.reached.load(std::memory_order_relaxed);
+          });
       // The user warning names only the first one; the log lists them all.
       for (const ModelVolume *volume : no_effect)
           BOOST_LOG_TRIVIAL(warning) << "[PreciseSeamNoEffect] object=\"" << volume->get_object()->name