15 June 2012

Unreal Engine 4 Hot Reload

Some of our readers have spotted the similarities of our runtime compilation and the Hot Reload function in UE4 (see the end of this video at around 9:50 , and the UE4 site). We don't know if their technique is inspired by or related to our work, but it certainly looks very familiar. Convergent designs frequently occur when conditions for their utilization are right, but we have a few friends who work at Epic so we're trying to find out. We're very happy to see this approach being used, and to mark the occasion we've added a 'compiling...' notification GUI element to the game, so you can see when something is being compiled even if you don't have the log window open.

When a compilation is running, the following element is shown (the dot animates as a scrolling '...' ):

And when complete you get the following:

We've yet to add any fancy transitions, and we don't show whether the completed compile was successful or not (though the log and log notification does), but perhaps we will at some stage!


  1. Relevant to your interests: http://www.bitsquid.se/presentations/cutting-the-pipe.pdf

  2. Hi,

    So ? Unreal Engine 4 Hot Reload is Runtime Compiled c++ or not samething but something similar ???


    1. With the source code now available I've been able to look into how UE4 does hot reload. It's not as sophisticated as RCC++, as it simply recompiles the entire game dll and the loads this - which can take a fairly long time and I've found it doesn't always work.


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