Add support for obj files with multiple connected components

Source/obj/WorldObject.cpp

@@ -8,6 +8,36 @@ struct pair_hash {
     }
 };
 
+std::vector<std::vector<int>> ConnectedComponents(const Graph& G) {
+    std::vector<std::vector<int>> components;
+    std::vector<bool> visited(G.GetNumVertices(), false);
+    list<int> L;
+
+    for (int i = 0; i < visited.size(); i++) {
+        // if condition should only be true for the first element in
+        // a new connected component
+        if (!visited[i]) {
+            components.emplace_back();
+            // Breadth First Search
+            L.push_back(i);
+            while (not L.empty()) {
+                int u = L.back();
+                L.pop_back();
+                if (visited[u]) continue;
+
+                visited[u] = true;
+                components.back().push_back(u);
+
+                for (int v : G.AdjList(u)) {
+                    L.push_back(v);
+                }
+            }
+        }
+    }
+
+    return components;
+}
+
 WorldObject::WorldObject(juce::InputStream& stream) {
     tinyobj::ObjReaderConfig reader_config;
     tinyobj::ObjReader reader;
@@ -16,6 +46,34 @@ WorldObject::WorldObject(juce::InputStream& stream) {
 
     vs = reader.GetAttrib().vertices;
 	numVertices = vs.size() / 3;
+
+    double x = 0.0, y = 0.0, z = 0.0;
+    double max = 0.0;
+
+    for (int i = 0; i < numVertices; i++) {
+        x += vs[i * 3];
+        y += vs[i * 3 + 1];
+        z += vs[i * 3 + 2];
+        if (std::abs(vs[i * 3]) > max) {
+            max = std::abs(vs[i * 3]);
+        }
+        if (std::abs(vs[i * 3 + 1]) > max) {
+            max = std::abs(vs[i * 3 + 1]);
+        }
+        if (std::abs(vs[i * 3 + 2]) > max) {
+            max = std::abs(vs[i * 3 + 2]);
+        }
+    }
+    x /= numVertices;
+    y /= numVertices;
+    z /= numVertices;
+
+    for (int i = 0; i < numVertices; i++) {
+        vs[i * 3] = (vs[i * 3] - x) / max;
+        vs[i * 3 + 1] = (vs[i * 3 + 1] - y) / max;
+        vs[i * 3 + 2] = (vs[i * 3 + 2] - z) / max;
+    }
+
     std::vector<tinyobj::shape_t> shapes = reader.GetShapes();
     
     std::unordered_set<std::pair<int, int>, pair_hash> edge_set;
@@ -43,48 +101,57 @@ WorldObject::WorldObject(juce::InputStream& stream) {
     }
 
     Graph graph(numVertices, edge_list);
-    pair<list<int>, double> solution = ChinesePostman(graph);
-    list<int>& path = solution.first;
 
-    double x = 0.0, y = 0.0, z = 0.0;
-    double max = 0.0;
+    std::vector<std::vector<int>> connected_components = ConnectedComponents(graph);
 
-    for (int i = 0; i < numVertices; i++) {
-		x += vs[i * 3];
-		y += vs[i * 3 + 1];
-		z += vs[i * 3 + 2];
-		if (std::abs(vs[i * 3]) > max) {
-			max = std::abs(vs[i * 3]);
-		}
-		if (std::abs(vs[i * 3 + 1]) > max) {
-			max = std::abs(vs[i * 3 + 1]);
-		}
-		if (std::abs(vs[i * 3 + 2]) > max) {
-			max = std::abs(vs[i * 3 + 2]);
-		}
-    }
-    x /= numVertices;
-    y /= numVertices;
-    z /= numVertices;
+    for (auto& connected_component : connected_components) {
+        std::vector<bool> present_vertices(graph.GetNumVertices(), false);
 
-    for (int i = 0; i < numVertices; i++) {
-        vs[i * 3] = (vs[i * 3] - x) / max;
-        vs[i * 3 + 1] = (vs[i * 3 + 1] - y) / max;
-        vs[i * 3 + 2] = (vs[i * 3 + 2] - z) / max;
-    }
-
-    int prevVertex = -1;
-    for (auto& vertex : path) {
-        if (prevVertex != -1) {
-            double x1 = vs[prevVertex * 3];
-            double y1 = vs[prevVertex * 3 + 1];
-            double z1 = vs[prevVertex * 3 + 2];
-            double x2 = vs[vertex * 3];
-            double y2 = vs[vertex * 3 + 1];
-            double z2 = vs[vertex * 3 + 2];
-
-            edges.push_back(Line3D(x1, y1, z1, x2, y2, z2));
+        for (int vertex : connected_component) {
+            present_vertices[vertex] = true;
+        }
+
+        std::unordered_map<int, int> obj_to_graph_vertex;
+        std::unordered_map<int, int> graph_to_obj_vertex;
+
+        int count = 0;
+        for (int i = 0; i < graph.GetNumVertices(); i++) {
+            if (present_vertices[i]) {
+                obj_to_graph_vertex[i] = i - count;
+                graph_to_obj_vertex[i - count] = i;
+            } else {
+                count++;
+            }
+        }
+
+        std::list<std::pair<int, int>> sub_edge_list;
+
+        for (int obj_start : connected_component) {
+            for (int obj_end : graph.AdjList(obj_start)) {
+                int graph_start = obj_to_graph_vertex[obj_start];
+                int graph_end = obj_to_graph_vertex[obj_end];
+                sub_edge_list.push_back(std::make_pair(graph_start, graph_end));
+            }
+        }
+
+        Graph subgraph(connected_component.size(), sub_edge_list);
+        pair<list<int>, double> solution = ChinesePostman(subgraph);
+        list<int>& path = solution.first;
+
+        int prevVertex = -1;
+        for (auto& graph_vertex : path) {
+            int vertex = graph_to_obj_vertex[graph_vertex];
+            if (prevVertex != -1) {
+                double x1 = vs[prevVertex * 3];
+                double y1 = vs[prevVertex * 3 + 1];
+                double z1 = vs[prevVertex * 3 + 2];
+                double x2 = vs[vertex * 3];
+                double y2 = vs[vertex * 3 + 1];
+                double z2 = vs[vertex * 3 + 2];
+
+                edges.push_back(Line3D(x1, y1, z1, x2, y2, z2));
+            }
+            prevVertex = vertex;
         }
-        prevVertex = vertex;
     }
 }