[Click to run Egui web demo](https://emilk.github.io/egui/index.html). Partial demo source: https://github.com/emilk/egui/blob/master/egui/src/demos/app.rs
[Hobogo](https://emilk.github.io/hobogo/index.html): A small game I made using Egui. Source: https://github.com/emilk/hobogo
[Click to run Egui web demo](https://emilk.github.io/egui/index.html). Partial demo source: <https://github.com/emilk/egui/blob/master/egui/src/demos/app.rs>
[Hobogo](https://emilk.github.io/hobogo/index.html): A small game I made using Egui. Source: <https://github.com/emilk/hobogo>
Egui is *not* a framework. Egui is a library you call into, not an environment you program for.
## State
Alpha state. It works well for what it does, but it lacks many features and the interfaces are still in flux. New releases will have breaking changes.
### Features:
### Features
* Widgets: label, text button, hyperlink, checkbox, radio button, slider, draggable value, text editing
* Layouts: horizontal, vertical, columns
@ -69,19 +68,21 @@ Alpha state. It works well for what it does, but it lacks many features and the
* Rendering: Anti-aliased rendering of lines, circles, text and convex polygons.
* Tooltips on hover
## How it works
Loop:
* Gather input (mouse, touches, keyboard, screen size, etc) and give it to Egui
* Run application code (Immediate Mode GUI)
* Tell Egui to tesselate the frame graphics to a triangle mesh
* Render the triangle mesh with your favorite graphics API (see OpenGL examples)
## Backends
Wherever you can render textured triangles you can use Egui.
### Official
I maintain two official Egui backends:
* [egui_web](crates.io/crates/egui_web) for making a web app. Compiles to WASM, renders with WebGL. [Click to run the Egui demo](https://emilk.github.io/egui/index.html).
@ -90,9 +91,11 @@ I maintain two official Egui backends:
The same code can be compiled to a native app or a web app.
### 3rd party
* [emigui-miniquad](https://github.com/not-fl3/emigui-miniquad): backend for [Miniquad](https://github.com/not-fl3/miniquad). [Web demo](https://not-fl3.github.io/miniquad-samples/emigui.html) and [demo source](https://github.com/not-fl3/good-web-game/blob/master/examples/emigui.rs).
### Writing your own Egui backend
You need to collect `egui::RawInput`, paint `egui::PaintJobs` and handle `egui::Output`. The basic structure is this:
``` rust
@ -110,33 +113,49 @@ loop {
}
```
#### Debugging your backend
#### My text is blurry
* Make sure you set the proper `pixels_per_point` in the input to Egui.
* Make sure the texture sampler is not off by half a pixel. Try nearest-neighbor sampler to check.
#### My windows are too transparent or too dark
* Make sure your texture sampler is clamped.
* Make sure you consider sRGB (gamma) in your shaders.
* Egui uses premultiplied alpha, so make sure your blending function is `(ONE, ONE_MINUS_SRC_ALPHA)`
## Other
### Conventions
* All coordinates are screen space coordinates, in logical "points" (which may consist of many physical pixels). Origin (0, 0) is top left.
* All colors have premultiplied alpha
### Inspiration
The one and only [Dear ImGui](https://github.com/ocornut/imgui) is a great Immediate Mode GUI for C++ which works with many backends. That library revolutionized how I think about GUI code and turned GUI programming from something I hated to do to something I now enjoy.
### Conventions and design choices
All coordinates are screen space coordinates, in logical "points" (which may consist of many physical pixels). Origin (0, 0) is top left.
All colors have premultiplied alpha.
Egui uses the builder pattern for construction widgets. For instance: `ui.add(Label::new("Hello").text_color(RED));` I am not a big fan of the builder pattern (it is quite verbose both in implementation and in use) but until Rust has named, default arguments it is the best we can do. To alleviate some of the verbosity there are common-case helper functions, like `ui.label("Hello");`.
#### Differences between Egui and Dear ImGui
Dear ImGui has has many years of development and so of course has more features. It has also been heavily optimized for speed, which Egui has not yet been.
Instead of using matching `begin/end` style function calls (which can be error prone) Egui prefers to use lambdas passed to a wrapping function. Lambdas are a bit ugly though, so I'd like to find a nicer solution to this.
Where Dear ImGui uses matching `Begin/End` style function calls, which can be error prone. Egui prefers to use lambdas passed to a wrapping function. Lambdas are a bit ugly though, so I'd like to find a nicer solution to this.
### Inspiration
Egui uses the builder pattern for construction widgets. For instance: `ui.add(Label::new("Hello").text_color(RED));` I am not a big fan of the builder pattern (it is quite verbose both in implementation and in use) but until we have named, default arguments it is the best we can do. To alleviate some of the verbosity there are common case helper functions, like `ui.label("Hello");`.
The one and only [Dear ImGui](https://github.com/ocornut/imgui) is a great Immediate Mode GUI for C++ which works with many backends. That library revolutionized how I think about GUI code and turned GUI programming from something I hated to do to something I now enjoy.
### Name
The name of the library and the project is "Egui" and pronounced as "e-gooey".
The library was originally called "Emigui", but was renamed to Egui in 2020.
Emil Ernerfeldt
4 years ago