ENH: add tool order function

1.Use min cost max flow to solve the tool order

jira:NEW

Signed-off-by: xun.zhang <xun.zhang@bambulab.com>
Change-Id: I909845039b67c7fe3ddd42580ad3f1d71d52262d

src/libslic3r/FilamentGroup.hpp

@@ -52,6 +52,7 @@ namespace Slic3r
         std::optional<std::function<bool(int, std::vector<int>&)>> get_custom_seq;
     };
 
+
     class KMediods
     {
         enum INIT_TYPE
@@ -83,5 +84,6 @@ namespace Slic3r
     private:
         std::vector<int>m_filament_labels;
     };
+
 }
 #endif // !FILAMENT_GROUP_HPP

src/libslic3r/GCode/ToolOrderUtils.cpp

@@ -8,6 +8,124 @@
 namespace Slic3r
 {
 
+    MCMF::MCMF(const FlushMatrix& matrix_, const std::vector<int>& u_nodes, const std::vector<int>& v_nodes)
+    {
+        matrix = matrix_;
+        l_nodes = u_nodes;
+        r_nodes = v_nodes;
+
+        total_nodes = u_nodes.size() + v_nodes.size() + 2;
+
+        source_id = total_nodes - 2;
+        sink_id = total_nodes - 1;
+
+        adj.resize(total_nodes);
+
+        //add edge from source to left nodes,set capacity to 1, cost to 0
+        for (int i = 0; i < l_nodes.size(); ++i)
+            add_edge(source_id, i, 1, 0);
+
+        //add edge from right nodes to sink,set capacity to 1, cost to 0
+        for (int i = 0; i < r_nodes.size(); ++i)
+            add_edge(l_nodes.size() + i, sink_id, 1, 0);
+
+        for (int i = 0; i < l_nodes.size(); ++i) {
+            int from_idx = i;
+            for (int j = 0; j < r_nodes.size(); ++j) {
+                int to_idx = l_nodes.size() + j;
+                add_edge(from_idx, to_idx, 1, get_distance(i, j));
+            }
+        }
+    }
+
+    std::vector<int> MCMF::solve()
+    {
+        while (spfa(source_id, sink_id));
+
+        std::vector<int>matching(l_nodes.size(), -1);
+        // to get the match info, just traverse the left nodes and
+        // check the edges with flow > 0 and linked to right nodes
+        for (int u = 0; u < l_nodes.size(); ++u) {
+            for (int eid : adj[u]) {
+                Edge& e = edges[eid];
+                if (e.flow > 0 && e.to >= l_nodes.size() && e.to < l_nodes.size() + r_nodes.size())
+                    matching[e.from] = r_nodes[e.to - l_nodes.size()];
+            }
+        }
+
+        return matching;
+    }
+
+    void MCMF::add_edge(int from, int to, int capacity, int cost)
+    {
+        adj[from].emplace_back(edges.size());
+        edges.emplace_back(from, to, capacity, cost);
+        //also add reverse edge ,set capacity to zero,cost to negative
+        adj[to].emplace_back(edges.size());
+        edges.emplace_back(to, from, 0, -cost);
+    }
+
+    bool MCMF::spfa(int source, int sink)
+    {
+        std::vector<int>dist(total_nodes, INF);
+        std::vector<bool>in_queue(total_nodes, false);
+        std::vector<int>flow(total_nodes, INF);
+        std::vector<int>prev(total_nodes, 0);
+
+        std::queue<int>q;
+        q.push(source);
+        in_queue[source] = true;
+        dist[source] = 0;
+
+        while (!q.empty()) {
+            int now_at = q.front();
+            q.pop();
+            in_queue[now_at] = false;
+
+            for (auto eid : adj[now_at]) //traverse all linked edges
+            {
+                Edge& e = edges[eid];
+                if (e.flow<e.capacity && dist[e.to]>dist[now_at] + e.cost) {
+                    dist[e.to] = dist[now_at] + e.cost;
+                    prev[e.to] = eid;
+                    flow[e.to] = std::min(flow[now_at], e.capacity - e.flow);
+                    if (!in_queue[e.to]) {
+                        q.push(e.to);
+                        in_queue[e.to] = true;
+                    }
+                }
+            }
+        }
+
+        if (dist[sink] == INF)
+            return false;
+
+        int now_at = sink;
+        while (now_at != source) {
+            int prev_edge = prev[now_at];
+            edges[prev_edge].flow += flow[sink];
+            edges[prev_edge ^ 1].flow -= flow[sink];
+            now_at = edges[prev_edge].from;
+        }
+
+        return true;
+    }
+
+    int MCMF::get_distance(int idx_in_left, int idx_in_right)
+    {
+        if (l_nodes[idx_in_left] == -1) {
+            return 0;
+            //TODO: test more here
+            int sum = 0;
+            for (int i = 0; i < matrix.size(); ++i)
+                sum += matrix[i][idx_in_right];
+            sum /= matrix.size();
+            return -sum;
+        }
+
+        return matrix[l_nodes[idx_in_left]][r_nodes[idx_in_right]];
+    }
+
     //solve the problem by searching the least flush of current filament
     static std::vector<unsigned int> solve_extruder_order_with_greedy(const std::vector<std::vector<float>>& wipe_volumes,
         const std::vector<unsigned int> curr_layer_extruders,
@@ -171,6 +289,7 @@ namespace Slic3r
     }
 
 
+
     // get best filament order of single nozzle
     std::vector<unsigned int> get_extruders_order(const std::vector<std::vector<float>>& wipe_volumes,
         const std::vector<unsigned int>& curr_layer_extruders,
@@ -202,7 +321,6 @@ namespace Slic3r
     }
 
 
-
     int reorder_filaments_for_minimum_flush_volume(const std::vector<unsigned int>& filament_lists,
         const std::vector<int>& filament_maps,
         const std::vector<std::vector<unsigned int>>& layer_filaments,
@@ -378,5 +496,4 @@ namespace Slic3r
 
         return cost;
     }
-
 }

src/libslic3r/GCode/ToolOrderUtils.hpp

@@ -9,6 +9,36 @@ namespace Slic3r {
 
 using FlushMatrix = std::vector<std::vector<float>>;
 
+class MCMF
+{
+    const int INF = std::numeric_limits<int>::max();
+    struct Edge
+    {
+        int from, to, capacity, cost, flow;
+        Edge(int u, int v, int cap, int cst) : from(u), to(v), capacity(cap), cost(cst), flow(0) {}
+    };
+
+public:
+    MCMF(const FlushMatrix &matrix_, const std::vector<int> &u_nodes, const std::vector<int> &v_nodes);
+    std::vector<int> solve();
+
+private:
+    void add_edge(int from, int to, int capacity, int cost);
+    bool spfa(int source, int sink);
+    int get_distance(int idx_in_left, int idx_in_right);
+
+private:
+    FlushMatrix matrix;
+    std::vector<int> l_nodes;
+    std::vector<int> r_nodes;
+
+    int total_nodes;
+    int source_id;
+    int sink_id;
+
+    std::vector<Edge> edges;
+    std::vector<std::vector<int>> adj;
+};
 
 std::vector<unsigned int> get_extruders_order(const std::vector<std::vector<float>> &wipe_volumes,
                                               const std::vector<unsigned int> &curr_layer_extruders,
@@ -24,6 +54,5 @@ int reorder_filaments_for_minimum_flush_volume(const std::vector<unsigned int> &
                                                std::optional<std::function<bool(int, std::vector<int> &)>> get_custom_seq,
                                                std::vector<std::vector<unsigned int>> *filament_sequences);
 
-
 }
 #endif // !TOOL_ORDER_UTILS_HPP

src/libslic3r/GCode/ToolOrdering.cpp

@@ -851,29 +851,22 @@ std::vector<int> ToolOrdering::get_recommended_filament_maps(const std::vector<s
 
     std::vector<int>ret(filament_nums,0);
     // if mutli_extruder, calc group,otherwise set to 0
-    if (extruder_nums == 2)
-    {
+    if (extruder_nums == 2) {
         std::vector<std::string> extruder_ams_count_str = print_config->extruder_ams_count.values;
-        auto extruder_ams_counts = get_extruder_ams_count(extruder_ams_count_str);
-        std::vector<int> group_size = { 16, 16 };
+        auto                     extruder_ams_counts    = get_extruder_ams_count(extruder_ams_count_str);
+        std::vector<int>         group_size             = {16, 16};
         if (extruder_ams_counts.size() > 0) {
             assert(extruder_ams_counts.size() == 2);
             for (int i = 0; i < extruder_ams_counts.size(); ++i) {
-                group_size[i] = 0;
-                const auto& ams_count = extruder_ams_counts[i];
-                for (auto iter = ams_count.begin(); iter != ams_count.end(); ++iter) {
-                    group_size[i] += iter->first * iter->second;
-                }
+                group_size[i]         = 0;
+                const auto &ams_count = extruder_ams_counts[i];
+                for (auto iter = ams_count.begin(); iter != ams_count.end(); ++iter) { group_size[i] += iter->first * iter->second; }
             }
         }
 
-        FilamentGroup fg(
-            nozzle_flush_mtx,
-            (int)filament_nums,
-            group_size
-        );
+        FilamentGroup fg(nozzle_flush_mtx, (int) filament_nums, group_size);
         fg.get_custom_seq = get_custom_seq;
-        ret = fg.calc_filament_group(layer_filaments, FGStrategy::BestFit);
+        ret               = fg.calc_filament_group(layer_filaments, FGStrategy::BestFit);
     }
 
     return ret;