From 3edec09a2e53906d8cae1f2b42ebebee25d24b4b Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Luk=C3=A1=C5=A1=20Hejl?= <hejl.lukas@gmail.com>
Date: Wed, 11 Sep 2024 14:43:21 +0200
Subject: [PATCH] SPE-1841: Use multi-material segmentation for all volumes of
 the model when at least one volume is painted.

For volumes that are not painted, we assume that they are entirely painted by the assigned extruder to this volume.
---
 src/libslic3r/MultiMaterialSegmentation.cpp | 11 ++++++++++-
 src/libslic3r/PrintApply.cpp                | 18 ++++++++++--------
 src/libslic3r/PrintObjectSlice.cpp          |  5 +----
 3 files changed, 21 insertions(+), 13 deletions(-)

diff --git a/src/libslic3r/MultiMaterialSegmentation.cpp b/src/libslic3r/MultiMaterialSegmentation.cpp
index 3fd60de3fd..add29c4e38 100644
--- a/src/libslic3r/MultiMaterialSegmentation.cpp
+++ b/src/libslic3r/MultiMaterialSegmentation.cpp
@@ -1602,6 +1602,15 @@ static void update_color_changes_using_color_projection_ranges(std::vector<Color
     }
 }
 
+static indexed_triangle_set_with_color extract_mesh_with_color(const ModelVolume &volume) {
+    if (const int volume_extruder_id = volume.extruder_id(); !volume.is_mm_painted() && volume_extruder_id >= 0) {
+        const TriangleMesh &mesh = volume.mesh();
+        return {mesh.its.indices, mesh.its.vertices, std::vector<uint8_t>(mesh.its.indices.size(), uint8_t(volume_extruder_id))};
+    }
+
+    return volume.mm_segmentation_facets.get_all_facets_strict_with_colors(volume);
+}
+
 std::vector<std::vector<ExPolygons>> multi_material_segmentation_by_painting(const PrintObject &print_object, const std::function<void()> &throw_on_cancel_callback)
 {
     const size_t                                   num_extruders = print_object.print()->config().nozzle_diameter.size();
@@ -1650,7 +1659,7 @@ std::vector<std::vector<ExPolygons>> multi_material_segmentation_by_painting(con
     BOOST_LOG_TRIVIAL(debug) << "MM segmentation - Slicing painted triangles - Begin";
     const std::vector<float> layer_zs = get_print_object_layers_zs(layers);
     for (const ModelVolume *mv : print_object.model_object()->volumes) {
-        const indexed_triangle_set_with_color mesh_with_color = mv->mm_segmentation_facets.get_all_facets_strict_with_colors(*mv);
+        const indexed_triangle_set_with_color mesh_with_color = extract_mesh_with_color(*mv);
         const Transform3d                     trafo           = print_object.trafo_centered() * mv->get_matrix();
         const MeshSlicingParams               slicing_params{trafo};
 
diff --git a/src/libslic3r/PrintApply.cpp b/src/libslic3r/PrintApply.cpp
index f30d811457..6cce84d5cc 100644
--- a/src/libslic3r/PrintApply.cpp
+++ b/src/libslic3r/PrintApply.cpp
@@ -1403,17 +1403,19 @@ Print::ApplyStatus Print::apply(const Model &model, DynamicPrintConfig new_full_
             print_object_regions->ref_cnt_inc();
         }
         std::vector<unsigned int> painting_extruders;
-        if (const auto &volumes = print_object.model_object()->volumes;
-            num_extruders > 1 &&
-            std::find_if(volumes.begin(), volumes.end(), [](const ModelVolume *v) { return ! v->mm_segmentation_facets.empty(); }) != volumes.end()) {
-
+        if (const auto &volumes = print_object.model_object()->volumes; num_extruders > 1 && print_object.model_object()->is_mm_painted()) {
             std::array<bool, static_cast<size_t>(TriangleStateType::Count)> used_facet_states{};
             for (const ModelVolume *volume : volumes) {
-                const std::vector<bool> &volume_used_facet_states = volume->mm_segmentation_facets.get_data().used_states;
+                if (volume->is_mm_painted()) {
+                    const std::vector<bool> &volume_used_facet_states = volume->mm_segmentation_facets.get_data().used_states;
 
-                assert(volume_used_facet_states.size() == used_facet_states.size());
-                for (size_t state_idx = 0; state_idx < std::min(volume_used_facet_states.size(), used_facet_states.size()); ++state_idx)
-                    used_facet_states[state_idx] |= volume_used_facet_states[state_idx];
+                    assert(volume_used_facet_states.size() == used_facet_states.size());
+                    for (size_t state_idx = 0; state_idx < std::min(volume_used_facet_states.size(), used_facet_states.size()); ++state_idx) {
+                        used_facet_states[state_idx] |= volume_used_facet_states[state_idx];
+                    }
+                } else if (const int volume_extruder_id = volume->extruder_id(); volume_extruder_id >= 0) {
+                    used_facet_states[volume_extruder_id] |= true;
+                }
             }
 
             for (size_t state_idx = static_cast<size_t>(TriangleStateType::Extruder1); state_idx < used_facet_states.size(); ++state_idx) {
diff --git a/src/libslic3r/PrintObjectSlice.cpp b/src/libslic3r/PrintObjectSlice.cpp
index 04fcde0152..754a2d1ef0 100644
--- a/src/libslic3r/PrintObjectSlice.cpp
+++ b/src/libslic3r/PrintObjectSlice.cpp
@@ -753,10 +753,7 @@ void PrintObject::slice_volumes()
     m_print->throw_if_canceled();
 
     // Is any ModelVolume MMU painted?
-    if (const auto& volumes = this->model_object()->volumes;
-        m_print->config().nozzle_diameter.size() > 1 &&
-        std::find_if(volumes.begin(), volumes.end(), [](const ModelVolume* v) { return !v->mm_segmentation_facets.empty(); }) != volumes.end()) {
-
+    if (m_print->config().nozzle_diameter.size() > 1 && this->model_object()->is_mm_painted()) {
         // If XY Size compensation is also enabled, notify the user that XY Size compensation
         // would not be used because the object is multi-material painted.
         if (m_config.xy_size_compensation.value != 0.f) {