dear-imgui-bevy

Bevy-native backend for dear-imgui-rs.

This crate integrates Dear ImGui with Bevy's ECS, window/input messages, WGPU render world, camera targets, and texture assets. It is intentionally not a wrapper around dear-imgui-winit plus dear-imgui-wgpu: Bevy owns the app loop and render schedules, so this backend follows Bevy's ownership model directly.

Quick Facts

Getting Started

Use the same Bevy version as the backend:

[dependencies]

bevy = "=0.19.0-rc.2"

dear-imgui-bevy = { version = "0.15", features = ["render"] }

dear-imgui-rs = "0.14"

A minimal overlay app registers ImguiPlugin, marks the camera that should receive the ImGui overlay, and draws UI from ImguiPrimaryContextPass:

use bevy::prelude::*;
use dear_imgui_bevy::{
    configure_example_context, ImguiContext, ImguiContexts, ImguiPlugin,
    ImguiPrimaryContextPass, render::ImguiOverlayCamera,
};

fn main() {
    App::new()
        .add_plugins(DefaultPlugins)
        .add_plugins(ImguiPlugin::default())
        .add_systems(Startup, setup)
        .add_systems(ImguiPrimaryContextPass, tools_ui)
        .run();
}

fn setup(mut commands: Commands, mut imgui: NonSendMut<ImguiContext>) {
    commands.spawn((Camera2d, ImguiOverlayCamera));
    configure_example_context(&mut imgui, false);
}

fn tools_ui(mut contexts: ImguiContexts) {
    let Some(ui) = contexts.primary_ui_mut() else {
        return;
    };

    ui.window("Tools").build(|| {
        ui.text("Dear ImGui is drawing in Bevy.");
    });
}

Application UI systems should draw through the Ui returned by ImguiContexts. Do not call Context::frame() or Context::render() yourself; the plugin owns the frame lifecycle.

Examples

Start with simple, then move to app_integration and game_engine as your integration needs grow.

Screenshots

Cargo Features

ImPlot, ImNodes, ImGuizmo, and other Ui-based extension crates compose with this backend through the same ImguiPrimaryContextPass frame. They are not dear-imgui-bevy feature flags; add the extension crates you use to your application dependencies directly.

Integration Guide

Frame Lifecycle

ImguiPlugin installs three main-world schedules:

1. ImguiBeginFrame translates Bevy input and opens the Dear ImGui frame.
2. ImguiPrimaryContextPass runs your UI systems against the already-open frame.
3. ImguiEndFrame renders once and stores an owned FrameSnapshot for the render world.

The main user-facing APIs are:

Render Targets and Scene Views

With the render feature enabled, the backend extracts ImGui frame snapshots into Bevy's render world and draws them through Bevy cameras. Add ImguiOverlayCamera to the camera that should receive the overlay for a render target.

Editor-style scene views usually render Bevy content into an Image, register that image through ImguiBevyTextures, and show it with ui.image(...). Add ImguiOverlayDisabled to the offscreen scene camera so the global ImGui overlay is not rendered back into the scene texture.

Docking and Multi-Viewport

Docking inside the primary Bevy window works like normal Dear ImGui docking: enable docking on the context, create a dockspace, then dock or drag windows inside it.

Native multi-viewport OS windows are experimental. They require a native target, render, and multi-viewport. The backend creates Bevy windows for Dear ImGui platform viewports, maps input/focus/cursor/IME feedback, and routes each viewport's draw data to the matching Bevy Window render target. Detached-window z-order and dock-target edge cases are still preview-grade.

Input Policy

The backend forwards Bevy input messages into Dear ImGui IO and does not consume or delete Bevy messages. Gameplay and editor systems should use ImguiInputCapture as a policy hint after ImGui has computed capture intent.

Current boundaries:

• pointer and keyboard capture are policy hints only;
• clipboard remains application-provided;
• accessibility nodes are not generated for Dear ImGui widgets;
• file drop, gamepad navigation, and Bevy picking integration are not part of this backend yet;
• wasm builds compile, but browser runtime IME and clipboard behavior depend on the host.

Development Checks

Recommended checks for this crate:

cargo check -p dear-imgui-bevy --no-default-features

cargo check -p dear-imgui-bevy --features render

cargo check -p dear-imgui-bevy --target wasm32-unknown-unknown --no-default-features

cargo check -p dear-imgui-bevy --target wasm32-unknown-unknown --features render

cargo nextest run -p dear-imgui-bevy

cargo nextest run -p dear-imgui-bevy --features render

cargo nextest run -p dear-imgui-bevy --features render,multi-viewport

cargo check -p dear-imgui-bevy --features render,multi-viewport --examples

Use cargo run commands from the examples table for manual smoke tests.