Dear ImGui is a bloat-free graphical user interface library for C++. It outputs optimized vertex buffers that you can render anytime in your 3D-pipeline enabled application. It is fast, portable, renderer agnostic and self-contained (no external dependencies).
This project contains Haskell bindings to the ImGui project. This allows you to rapidly put together graphical user interfaces in Haskell, with a particular focus to games and graphics intensive applications.
To get started, we'll build the following:
dear-imgui.hs can be used like a normal Haskell library. If you use Cabal,
simply add dear-imgui to your build-depends. ImGui supports a variety of
backends, and you will need to choose your backend at configuration time.
Backends can be enabled using Cabal flags, and these can be set through the
cabal.project file. For example, if you want to use a combination of SDL and
OpenGL:
package dear-imgui
flags: +sdl +opengl3
With this done, the following module is the "Hello, World!" of ImGui:
{-# language OverloadedStrings #-}
module Main ( main ) where
import DearImGui
import DearImGui.OpenGL3
import DearImGui.SDL
import DearImGui.SDL.OpenGL
import Graphics.GL
import SDL
import Control.Monad.Managed
import Control.Monad.IO.Class ()
import Control.Monad (when, unless)
import Control.Exception (bracket, bracket_)
main :: IO ()
main = do
-- Initialize SDL
initializeAll
runManaged $ do
-- Create a window using SDL; as we're using OpenGL, we enable OpenGL too
window <- do
let title = "Hello, Dear ImGui!"
let config = defaultWindow { windowGraphicsContext = OpenGLContext defaultOpenGL }
managed $ bracket (createWindow title config) destroyWindow
-- Create an OpenGL context
glContext <- managed $ bracket (glCreateContext window) glDeleteContext
-- Create an ImGui context
_ <- managed $ bracket createContext destroyContext
-- Initialize ImGui's SDL2 backend
managed_ $ bracket_ (sdl2InitForOpenGL window glContext) sdl2Shutdown
-- Initialize ImGui's OpenGL backend
managed_ $ bracket_ openGL3Init openGL3Shutdown
liftIO $ mainLoop window
mainLoop :: Window -> IO ()
mainLoop window = unlessQuit $ do
-- Tell ImGui we're starting a new frame
openGL3NewFrame
sdl2NewFrame
newFrame
-- Build the GUI
withWindowOpen "Hello, ImGui!" $ do
-- Add a text widget
text "Hello, ImGui!"
-- Add a button widget, and call 'putStrLn' when it's clicked
button "Clickety Click" >>= \clicked ->
when clicked $ putStrLn "Ow!"
-- Show the ImGui demo window
showDemoWindow
-- Render
glClear GL_COLOR_BUFFER_BIT
render
openGL3RenderDrawData =<< getDrawData
glSwapWindow window
mainLoop window
where
-- Process the event loop
unlessQuit action = do
shouldQuit <- gotQuitEvent
unless shouldQuit action
gotQuitEvent = do
ev <- pollEventWithImGui
case ev of
Nothing ->
return False
Just event ->
(isQuit event ||) <$> gotQuitEvent
isQuit event =
eventPayload event == QuitEventIf you would like to help dear-imgui, here's how you can get started.
The best path to development is using Nix. Once you have Nix installed (either in your operating system, or by running NixOS), you can enter a development shell:
$ nix-shell
You should now be in a bash shell where you can run cabal build all,
cabal run readme, etc.
If you experience any difficulties, please don't hesistate to raise an issue.
Feel free to raise bugs, questions and feature requests on the GitHub issue tracker.
We have a Matrix room at
#dear-imgui.hs:ocharles.org.uk.
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