Dear ImGui is an immediate-mode graphical user interface library that is very lightweight and easy to use. It can be very useful when creating debugging tools.
Please note that this is a forked project from [https://github.com/segross/UnrealImGui](https://github.com/segross/UnrealImGui). I do not take credit for the work he's put into making Dear ImGui work in Unreal Engine. The work I've done to this fork is listed below.
I've removed large portions of this readme.md to keep redundant information between the base project and this fork to a minimum. If you wish to read the original readme.md, please see this link: [UnrealImGui ReadMe.md](https://github.com/segross/UnrealImGui/blob/master/README.md).
-`ImGui::IsKey*` now functional with all known ImGui keys.
- Updated input handling flow to be [standard compliant](https://github.com/ocornut/imgui/issues/4921) with Dear ImGui 1.87 which makes ImGui react better at low FPS. Will add `IMGUI_DISABLE_OBSOLETE_KEYIO` preprocessor once I've ripped out old style input.
- Allowed `UTexture` for Texture Manager so render targets can also be rendered to quads rather than just being limited to using `UTexture2D` instances.
On top of reading the base repository's [How to Set up](https://github.com/segross/UnrealImGui/blob/master/README.md#how-to-set-up) segment, you'll need to add the following line to your `[GameName].Build.cs` file otherwise you'll get linking errors:
It's pretty easy to use ImPlot, it's pretty much the same drill as using Dear ImGui with the UnrealImGui plugin. You can see documentation on how to use ImPlot here: [ImPlot](https://github.com/epezent/implot).
The only thing you won't need to do is call the `ImPlot::CreateContext()` and `ImPlot::DestroyContext` routines as they're already called when ImGui's context is created within UnrealImGui's guts.
One might want to render viewports into the world in an ImGui window. You can do this pretty simply by generating a `UTextureRenderTarget2D` then assigning that to a `ASceneCapture2D` actor in your world. Here's some sample code for generating an correctly managing the `UTextureRenderTarget2D`:
If you're using a scene capture and your quad is not drawing at all, make sure your scene capture "Capture Source" is set to "Final Color (with tone curve) in Linear sRGB gamut" to avoid alpha being set to 0 (since there's no way to instruct ImGui to ignore alpha without modding the core UnrealImGui plugin).
If you're getting crashes or seg faults during rendering, make sure you're using `UPROPERTY()` on your class variables!
Adding custom fonts is fairly simple. As a more complex and more commonly done, we're going to embed and build FontAwesome 6 into the font atlas. First thing you'll need is a binary C version of the FontAwesome font along with the necessary [companion descriptors](https://github.com/juliettef/IconFontCppHeaders/blob/main/IconsFontAwesome6.h). The descriptors are pre-generated, however if you have a new version of FA you wish to use, then use the Python script in that repository. As for the binary C, you'll need to compile Dear ImGui's [binary_to_compressed_c.cpp](https://github.com/ocornut/imgui/blob/master/misc/fonts/binary_to_compressed_c.cpp).
Once you have the necessary files, you'll need to encode your FontAwesome font using the command:
The only mandatory field here is `-nocompress` as this instructs the encoder to create an uncompressed binary file (1:1) since currently there's no immediate support for compressed fonts.
Move over your descriptors and your binary C font file to an appropriate location for inclusion in your Unreal Engine project. The following code is how to instruct ImGui to build the font atlas with your FontAwesome font:
That's it. Make sure you execute the above code once at the beginning of the first ImGui frame (or at any point of your framework where the ImGui context has been initialized correctly) and it should build the main atlas with FontAwesome inside it. ImFontConfig lifetime is currently managed via reference counting (`TSharedPtr`).
### Using the icons
```cpp
#include "IconsFontAwesome6.h"
void OnPaint()
{
ImGui::Text(ICON_FA_AWARD);
}
```
Pretty simple. Building FStrings that incorporate FontAwesome icons however gets a little trickier:
