Why does the EULA Section 1.D exist?

Good Day,

Today I worked with Legal to understand better what the restrictions are on building a language runtime that is integrated into UE4, and distributed as a plugin and I cannot lie when I say it’s hitting close to home. I have been working on such a plugin that connects the V8 JS Engine to UE4 as a scripting language and the amount of time that I have spent on it so far (about 2 weeks a month for the last year and a half) is valuable to me. As such, selling the runtime and distributing it on the market has been a hope of mine for at least a year. With this element in the EULA making a pretty clear statement that my work has to be open and available to the public it makes for a rough sell.

The question I would like to understand is, why this entry is necessary/wanted when there are many other binary plugins into proprietary systems (SpeedTree, Substance, Steam just to name a few that start with the letter S) that are already available and distributed as plugins.


To clarify why that section of the EULA was added, Sweeney has made a forum post with full details: LINK

Here’s a key excerpt from the post:

[…]Programming language integrations
are very different in nature than
middleware integrations such as
SpeedTree and Substance in this
regard. Though the later are
feature-rich, they are fairly
self-contained in their interactions
with UE4. A programming language
integration can interact with just
about any part of the engine and
therefore has unlimited scope.

For these reasons, we updated the UE4
EULA to require redistributed
programming language integrations to
be free and open source, so that if
one gained a critical mass in
popularity, Epic could adopt it and
ensure its future viability in the
areas described above.[…]

Please let me know if there is anything else I can assist you with.


Understood and thank you for the link.

I guess the only issue i take with this is that it stifles the drive into this space by making it so you have to adhere to this very narrow area for ventures. I am all for open source development, it is only more complicated to find a business reason to step out and start the work building it. Thankfully, V8 and its components are open sourced, so the only part that is of any significance is the binding I’ve built which weighing the options, the ROI here is significant even with one road being open sourced.