Add multi-editor example

- Side-by-side node editors seem to work! 🎉

example/multi_editor.cpp

@@ -0,0 +1,114 @@
+#include "node_editor.h"
+#include <imnodes.h>
+#include <imgui.h>
+#include <SDL_scancode.h>
+
+#include <vector>
+
+namespace example
+{
+namespace
+{
+struct Node
+{
+    int id;
+    float value;
+};
+
+struct Link
+{
+    int id;
+    int start_attr, end_attr;
+};
+
+struct Editor
+{
+    imnodes::EditorContext* context = nullptr;
+    std::vector<Node> nodes;
+    std::vector<Link> links;
+    int current_id = 0;
+};
+
+void show_editor(const char* editor_name, Editor& editor)
+{
+    imnodes::EditorContextSet(editor.context);
+
+    ImGui::Begin(editor_name);
+    ImGui::TextUnformatted("A -- add node");
+
+    imnodes::BeginNodeEditor();
+
+    for (Node& node : editor.nodes)
+    {
+        imnodes::BeginNode(node.id);
+
+        imnodes::BeginNodeTitleBar();
+        ImGui::TextUnformatted("node");
+        imnodes::EndNodeTitleBar();
+
+        imnodes::BeginInputAttribute(node.id << 8);
+        ImGui::TextUnformatted("input");
+        imnodes::EndAttribute();
+
+        ImGui::PushItemWidth(120.0f);
+        ImGui::DragFloat("value", &node.value, 0.01f);
+        ImGui::PopItemWidth();
+
+        imnodes::BeginOutputAttribute(node.id << 16);
+        const float text_width = ImGui::CalcTextSize("output").x;
+        ImGui::Indent(120.f + ImGui::CalcTextSize("value").x - text_width);
+        ImGui::TextUnformatted("output");
+        imnodes::EndAttribute();
+
+        imnodes::EndNode();
+    }
+
+    for (const Link& link : editor.links)
+    {
+        imnodes::Link(link.id, link.start_attr, link.end_attr);
+    }
+
+    imnodes::EndNodeEditor();
+
+    {
+        Link link;
+        if (imnodes::IsLinkCreated(&link.start_attr, &link.end_attr))
+        {
+            link.id = ++editor.current_id;
+            editor.links.push_back(link);
+        }
+    }
+
+    if (ImGui::IsKeyReleased(SDL_SCANCODE_A) &&
+        ImGui::IsWindowFocused(ImGuiFocusedFlags_RootAndChildWindows))
+    {
+        const int node_id = ++editor.current_id;
+        imnodes::SetNodeScreenSpacePos(node_id, ImGui::GetMousePos());
+        editor.nodes.push_back(Node{node_id, 0.f});
+    }
+
+    ImGui::End();
+}
+
+Editor editor1;
+Editor editor2;
+} // namespace
+
+void NodeEditorInitialize()
+{
+    editor1.context = imnodes::EditorContextCreate();
+    editor2.context = imnodes::EditorContextCreate();
+}
+
+void NodeEditorShow()
+{
+    show_editor("editor1", editor1);
+    show_editor("editor2", editor2);
+}
+
+void NodeEditorShutdown()
+{
+    imnodes::EditorContextFree(editor1.context);
+    imnodes::EditorContextFree(editor2.context);
+}
+} // namespace example

premake5.lua

@@ -80,3 +80,5 @@ workspace "imnodes"
     imnodes_example_project("saveload", "save_load.cpp")
 
     imnodes_example_project("colornode", "color_node_editor.cpp")
+
+    imnodes_example_project("multieditor", "multi_editor.cpp")