node editor: draw edges

src/gui/node_editor.h

@@ -92,6 +92,7 @@ public:
             ImVec2 offset = canvas_pos - scrolling; // TODO: add scrolling
 
             // -- Draw the grid
+            draw_list->ChannelsSetCurrent(0);
             if (show_grid) {
                 ImVec2 local_offset = ImGui::GetCursorPos() - scrolling;
 
@@ -105,6 +106,17 @@ public:
                                        ImVec2(canvas_size.x, y)+canvas_pos, color);
             }
 
+
+            draw_list->ChannelsSetCurrent(0);
+            for (const auto &edge : edgeList) {
+                auto head = offset + edge.lhs->slot_location(GuiNode::OUT, edge.fromSlot);
+                auto tail = offset + edge.rhs->slot_location(GuiNode::IN,  edge.fromSlot);
+
+                draw_list->AddBezierCurve(head, head+ImVec2(50, 0),
+                                          tail+ImVec2(-50, 0), tail,
+                                          ImColor(200, 200, 200), 3.0f);
+            }
+
             Rect viewportRect = Rect(scrolling, canvas_size);
 
             for (const auto &node : nodeList) {