Guide Dear ImGui

A Dear ImGui settings menu in C# and Rust

Dear ImGui isn't only for C++. Here is the same small settings window — two checkboxes, a volume slider and an Apply button — in C# with ImGui.NET and in Rust with imgui-rs.

C# with ImGui.NET

ImGui.NET mirrors the C++ API closely; values you change are passed with ref. Run this between ImGui.NewFrame() and ImGui.Render(), with whichever renderer you use (for example Silk.NET).

C#
using System.Numerics;
using ImGuiNET;

bool vsync = true;
bool fullscreen = false;
float volume = 50f;

void SettingsWindow()
{
    ImGui.SetNextWindowSize(new Vector2(380, 0), ImGuiCond.FirstUseEver);
    ImGui.Begin("Game Settings");

    ImGui.Checkbox("V-Sync", ref vsync);
    ImGui.Checkbox("Fullscreen", ref fullscreen);
    ImGui.SliderFloat("Volume", ref volume, 0f, 100f, "%.0f");

    if (ImGui.Button("Apply", new Vector2(-1, 0)))
    {
        ApplySettings(vsync, fullscreen, volume);
    }

    ImGui.End();
}

Rust with imgui-rs

imgui-rs uses a builder for windows and a closure for their contents; widgets take &mut values.

Rust
use imgui::{Condition, Ui};

struct Settings {
    vsync: bool,
    fullscreen: bool,
    volume: f32,
}

fn settings_window(ui: &Ui, s: &mut Settings) {
    ui.window("Game Settings")
        .size([380.0, 0.0], Condition::FirstUseEver)
        .build(|| {
            ui.checkbox("V-Sync", &mut s.vsync);
            ui.checkbox("Fullscreen", &mut s.fullscreen);
            ui.slider("Volume", 0.0, 100.0, &mut s.volume);

            if ui.button_with_size("Apply", [-1.0, 0.0]) {
                apply_settings(s);
            }
        });
}

What differs from C++

  • State lives in your variables or struct, passed by ref (C#) or &mut (Rust) — the same idea as pointers in C++.
  • Sizes are Vector2 in C# and [f32; 2] arrays in Rust instead of ImVec2.
  • Begin / End become a builder with a closure in Rust, so you can't forget End().

Kavro designs the window once and generates it for C++ (Dear ImGui + DirectX 11), C# (ImGui.NET + Silk.NET on .NET 8) or Rust (imgui-rs + glium) — with the project files to build it.

More guides

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