YourGameWindow.cs

using System;
using System.Collections.Generic;
using System.Numerics;
using SDL2;
using ImGuiNET;
using ImGuiSDL2CS;

namespace YourGameNamespace {
    public class YourGameWindow : ImGuiSDL2CSWindow {

        private TextInputBuffer[] _TextInputBuffers;

        public YourGameWindow()
            : base("Your Game Window Title") {

            //////// OPTIONAL ////////
            // This affects the "underlying" SDL2Window and can be used for a quick game loop sketch.
            // Don't set those and only ImGui gets rendered / handled.
            // They're delegate fields so that one can override those from outside.
            OnEvent = MyEventHandler;
            OnLoop = MyGameLoop;

        }

        // Create any possibly unmanaged resources (textures, buffers) here.
        protected override void Create() {
            base.Create();

            _TextInputBuffers = TextInputBuffer.CreateBuffers(2);
        }

        // Dispose any possibly unmanaged resources (textures, buffers) here.
        protected override void Dispose(bool disposing) {
            TextInputBuffer.DisposeBuffers(_TextInputBuffers);

            base.Dispose(disposing);
        }

        // This runs between ImGuiSDL2CSHelper.NewFrame and ImGuiSDL2CSHelper.Render.
        public unsafe override void ImGuiLayout() {
            ImGui.BeginWindow("Window 1");
            ImGui.LabelText("Label", "Text");
            ImGui.InputText("Some text input", _TextInputBuffers[0].Buffer, _TextInputBuffers[0].Length, InputTextFlags.Default, ImGuiSDL2CSHelper.OnTextEdited);
            ImGui.EndWindow();

            ImGui.BeginWindow("Window 2");
            ImGui.LabelText("Label", "Text");
            ImGui.InputText("Some other text input", _TextInputBuffers[1].Buffer, _TextInputBuffers[1].Length, InputTextFlags.Default, ImGuiSDL2CSHelper.OnTextEdited);
            ImGui.EndWindow();
        }

        //////// OPTIONAL ////////

        // Processs any SDL2 events manually if required.
        // Return false to not allow the default event handler to process it.
        public bool MyEventHandler(SDL2Window _self, SDL.SDL_Event e) {
            // We're replacing OnEvent and thus call ImGuiSDL2CSHelper.OnEvent manually.
            if (!ImGuiSDL2CSHelper.OnEvent(e, ref g_MouseWheel, g_MousePressed))
                return false;

            // Any custom event handling can happen here.

            return true;
        }

        // Any custom game loop should end up here.
        // Setting the window.IsActive = false stops the loop.
        public void MyGameLoop(SDL2Window _self) {
            // This is the default implementation.

            // Using MiniTK (not OpenTK) to provide access to OpenGL methods.
            // Alternatively, use SDL_GL_GetProcAddress on your own.
            OpenTK.Graphics.OpenGL.GL.ClearColor(0.1f, 0.125f, 0.15f, 1f);
            OpenTK.Graphics.OpenGL.GL.Clear(OpenTK.Graphics.OpenGL.ClearBufferMask.ColorBufferBit);

            // This calls ImGuiSDL2CSHelper.NewFrame, the overridden ImGuiLayout, ImGuiSDL2CSHelper.Render and renders it.
            // ImGuiSDL2CSHelper.NewFrame properly sets up ImGuiIO and ImGuiSDL2CSHelper.Render renders the draw data.
            ImGuiRender();

            // Finally, swap.
            Swap();
        }

    }
}