ImGui Node Editor integration: introduction and acknowledgements

[pthom]

imgui-node-editor provides a very advanced node editor built using Dear ImGui.

Python bindings

Using the python bindings

Using the python bindings works quite well, and is a pleasure to use. Here are some examples. And here is a 1 minute video demonstration of a possible usage inside python, around functions compositions.

Technical notes about the python bindings

The python bindings declarations are here: imgui_node_editor.pyi

In order to simplify the creation of NodeId, LinkId and PinId, a wrapper for those Id is provided in python.

When using the default context provided by ImmApp, there is a dedicated API

imgui-node-editor fork

The bindings are built on a fork of imgui-node-editor on the imgui_bundle branch.

This fork adds two small patches: a patch for an issue inside ed::EditorContext::Begin (for which a PR is proposed) and a patch that stores the SettingsFile under the form of a string (instead of a const char*), so that it can be modified from python

Integration inside ImmApp:

ImmApp is a thin extension of HelloImGui that enables to easily initialize the ImGuiBundle addons that require additional setup at startup (note: using ImmApp is perfectly optional. It is possible to instantiate a standard ImGui app manually)

Automatic context creation (C++ and Python)

When using ImmApp, a context for imgui-node-editor can be created/destroyed automatically, by filling an AddOnsParams
structure.

For example, this C++ demo:

C++ demo code

can be run by simply adding this main function:

#include "immapp/immapp.h"
int main()
{
    HelloImGui::SimpleRunnerParams params{.guiFunction = demo_romeo_and_juliet};
    ImmApp::AddOnsParams addons {.withNodeEditor = true};
    ImmApp::Run(params, addons);
}

This global context is available via this api

Using ImmApp to quickly build a C++ app with imgui-node-editor:

The previous C++ example can be compiled standalone by simply adding this CMakeLists.txt from the _example_integration folder

(alternatively, HelloImGui provides a similar quickstart example, which can be used to compile an application where imgui-node-editor code is provided manually)