A complete example using Veldrid.ImGui

complete-imgui-example.cs

using ImGuiNET;
using Veldrid;
using Veldrid.StartupUtilities;

class Program
{
    static void Main(string[] args)
    {
        VeldridStartup.CreateWindowAndGraphicsDevice(
            new WindowCreateInfo(100, 100, 1280, 720, Veldrid.WindowState.Normal, "ImGui Example"),
            out var window,
            out var gd);
        ImGuiRenderer imguiRenderer = new ImGuiRenderer(
            gd, gd.MainSwapchain.Framebuffer.OutputDescription,
            (int)gd.MainSwapchain.Framebuffer.Width, (int)gd.MainSwapchain.Framebuffer.Height);
        var cl = gd.ResourceFactory.CreateCommandList();

        while (window.Exists)
        {
            var input = window.PumpEvents();
            if (!window.Exists) { break; }
            imguiRenderer.Update(1f / 60f, input); // Compute actual value for deltaSeconds.

            // Draw stuff
            ImGui.Text("Hello World");

            cl.Begin();
            cl.SetFramebuffer(gd.MainSwapchain.Framebuffer);
            cl.ClearColorTarget(0, RgbaFloat.Black);
            imguiRenderer.Render(gd, cl);
            cl.End();
            gd.SubmitCommands(cl);
            gd.SwapBuffers(gd.MainSwapchain);
        }
    }
}