diff --git a/src/graph/case.cc b/src/graph/case.cc
index 05f896a..2ee6bbc 100644
--- a/src/graph/case.cc
+++ b/src/graph/case.cc
@@ -3,7 +3,7 @@
 
 void GraphCase::render(SvgGraph &svg, const CaseSkin &skin) const {
     /// precompute size info
-    auto raw_code = (uint64_t)code;
+    auto raw_code = code;
     uint32_t block_width_2 = block_width * 2 + block_gap;
     uint32_t case_width = block_width * 4 + block_gap * 5;
     uint32_t case_height = block_width * 5 + block_gap * 6;
diff --git a/src/graph/graph.cc b/src/graph/graph.cc
index 578c310..52cd3a5 100644
--- a/src/graph/graph.cc
+++ b/src/graph/graph.cc
@@ -79,6 +79,8 @@ void Graph::svg_demo(Analyse::track_data_t track_data) {
 
                 if (ret.second) { // insert success
                     graph_layer[i - 1].emplace_back(&ret.first->second);
+                } else {
+                    graph_data[src->code].next.emplace_back(graph_data[c->code].layer_index);
                 }
             }
         }
@@ -95,22 +97,49 @@ void Graph::svg_demo(Analyse::track_data_t track_data) {
     uint64_t graph_width = CASE_WIDTH * max_width + CASE_GAP_X * (max_width + 1);
     uint64_t graph_height = CASE_HEIGHT * max_height + CASE_GAP_Y * (max_height + 1);
 
+
+    auto case_address = [this, &graph_width, &graph_layer](uint32_t i, uint32_t j) -> Point {
+        uint64_t case_top = CASE_GAP_Y * (i + 1) + CASE_HEIGHT * i;
+        uint64_t offset = (graph_width - (CASE_GAP_X * (graph_layer[i].size() + 1) + CASE_WIDTH * graph_layer[i].size())) / 2;
+        uint64_t case_left = offset + CASE_GAP_X * (j + 1) + CASE_WIDTH * j;
+
+        return Point {case_left, case_top};
+    };
+
     auto svg = SvgGraph(graph_width, graph_height);
 
+//    std::cout << graph_layer[0][0]->next.size() << std::endl;
+
     for (uint32_t i = 0; i < graph_layer.size(); ++i) {
+//    for (uint32_t i = 0; i < 1; ++i) {
 
-        uint64_t case_top = CASE_GAP_Y * (i + 1) + CASE_HEIGHT * i;
+//        uint64_t case_top = CASE_GAP_Y * (i + 1) + CASE_HEIGHT * i;
 
-        uint64_t offset = (graph_width - (CASE_GAP_X * (graph_layer[i].size() + 1) + CASE_WIDTH * graph_layer[i].size())) / 2;
+//        uint64_t offset = (graph_width - (CASE_GAP_X * (graph_layer[i].size() + 1) + CASE_WIDTH * graph_layer[i].size())) / 2;
 
         for (uint32_t j = 0; j < graph_layer[i].size(); ++j) {
-            uint64_t case_left = offset + CASE_GAP_X * (j + 1) + CASE_WIDTH * j;
+//            uint64_t case_left = offset + CASE_GAP_X * (j + 1) + CASE_WIDTH * j;
 
-            auto g = GraphCase({case_left, case_top}, RawCode::unsafe_create(graph_layer[i][j]->code), BLOCK_GAP, BLOCK_LENGTH);
+//            auto g = GraphCase({case_left, case_top}, graph_layer[i][j]->code, BLOCK_GAP, BLOCK_LENGTH);
+            auto g = GraphCase(case_address(i, j), graph_layer[i][j]->code, BLOCK_GAP, BLOCK_LENGTH);
             g.render(svg, skin);
 
-        }
+            for (const auto next : graph_layer[i][j]->next) {
+
+                auto s = case_address(i, j);
+                auto e = case_address(i + 1, next);
+
+                s.x += CASE_WIDTH / 2;
+                s.y += CASE_HEIGHT + LINE_OFFSET;
 
+                e.x += CASE_WIDTH / 2;
+                e.y -= LINE_OFFSET;
+
+                auto line = new SvgLine(s, e);
+                svg.insert(line);
+            }
+
+        }
     }
 
     std::cout << svg.dump() << std::endl;
diff --git a/src/graph/graph.h b/src/graph/graph.h
index 4f462e1..e3d8892 100644
--- a/src/graph/graph.h
+++ b/src/graph/graph.h
@@ -25,12 +25,12 @@ public:
 class GraphCase {
 public:
     Point start;
-    RawCode code;
+    uint64_t code;
     uint32_t block_gap;
     uint32_t block_width;
 
     void render(SvgGraph &svg, const CaseSkin &skin) const;
-    GraphCase(Point p, RawCode c, uint32_t gap, uint32_t width) : start(p), code(c) {
+    GraphCase(Point p, uint64_t c, uint32_t gap, uint32_t width) : start(p), code(c) {
         block_gap = gap;
         block_width = width;
     }
@@ -49,6 +49,8 @@ public:
     uint64_t CASE_WIDTH = BLOCK_LENGTH * 4 + BLOCK_GAP * 5;
     uint64_t CASE_HEIGHT = BLOCK_LENGTH * 5 + BLOCK_GAP * 6;
 
+    uint64_t LINE_OFFSET = 3;
+
     void svg_demo(Analyse::track_data_t track_data);
 
 };
diff --git a/src/graph/svg/svg.cc b/src/graph/svg/svg.cc
index aa0a323..06d3816 100644
--- a/src/graph/svg/svg.cc
+++ b/src/graph/svg/svg.cc
@@ -14,7 +14,20 @@ std::string SvgLine::dump() const {
 
     /// basic attributes of svg-line
 
-    return "<line />";
+    std::string xml = "<line ";
+    xml += "x1=\"" + std::to_string(start.x) + "\" ";
+    xml += "y1=\"" + std::to_string(start.y) + "\" ";
+    xml += "x2=\"" + std::to_string(end.x) + "\" ";
+    xml += "y2=\"" + std::to_string(end.y) + "\" ";
+
+    std::string style = "stroke:blue;stroke-width:1;";
+
+    //    <line x1="0" y1="0" x2="200" y2="200" style="stroke:rgb(255,0,0);stroke-width:2"/>
+
+
+    // TODO: svg-line css style
+
+    return xml + "style=\"" + style + "\" />";
 
 }
 
diff --git a/src/graph/svg/svg.h b/src/graph/svg/svg.h
index dc7c22e..09ab76c 100644
--- a/src/graph/svg/svg.h
+++ b/src/graph/svg/svg.h
@@ -28,8 +28,7 @@ public:
 
     ~SvgLine() override = default;
     std::string dump() const override;
-
-    // TODO: SvgLine(...)
+    SvgLine(Point s, Point e) : start(s), end(e) {}
 };
 
 /// SVG rectangle element