LivePP2

A simple Unreal Engine integration plugin for Molecular Matters Live++ 2.

This is much faster to iterate with than the default Live++ integration, but it comes with an additional restriction: Neither UBT nor UHT will run. If you make any changes to headers that change the line numbers UHT macros are on, it will fail to compile the patch. Basic rule: Just don't use hot reload for header changes.

Supported Platforms

The plugin will work in the editor aswell as packaged builds in Debug, DebugGame and Development config. I only implemented support for Windows.

Supported Live++ Versions

You must use Live++ version >= 2.4.0 due to breaking API changes.

Unity Splitting Compatibility

If you intend to reload modules that use the UE_INLINE_GENERATED_CPP_BY_NAME macro (such as any engine modules), you need to make a small change to UBT. The .gen.cpp files that are included by the macro are often not capable of compiling on their own, but due to ending in .cpp, Live++ will attempt to apply Unity Splitting to them. To fix this, use find/replace to change .gen.cpp to .gen.hpp in Engine/Source/Programs/Shared/*, Engine/Source/Programs/UnrealBuildTool/* and ObjectMacros.h. After a rebuild, everything will work as it used to, except the files no longer get split out on hot reload.

Installation

Install this plugin to your project.
Download the official Live++ release and place the LivePP folder next to the PLACE_LIVEPP_FOLDER_HERE file in Source/ThirdParty/LivePPSDK.
Disable Live Coding in Unreal Editor from Editor Preferences -> Live Coding.
Add -LivePP2 to the launch arguments in your IDE.

Usage (Editor)

Start the editor.
Modify a file and use Ctrl-Alt-F11 shortcut as usual.

Usage (Packaged)

Start the packaged build with -LivePP2 argument.
Modify a file and use Ctrl-Alt-F11 shortcut as usual.