License of Emerald Mine game engine

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dave
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Post by dave » Sun Aug 08, 2010 6:29 am

>>Was it because of possible copyright issues?
>>
>Yes.
>

this is interesting, since the Emerald Mine software in rocksndiamonds is used without permission.
possible copyright issues?

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Holger
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Post by Holger » Sun Aug 08, 2010 8:50 am

Fortunately, the Emerald Mine engine included in R'n'D is free of any copyright problems. I have an explicit permission from the original author of the game engine code written by mail. (And even if I would not have such an explicit permission, it would be no problem, as the code is licensed under the BSD license, which makes using it within the R'n'D project perfectly fine.)

So there are no copyright problems at this part of the game.

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Post by dave » Sun Aug 08, 2010 10:37 am

> I have an explicit permission from the original author of the game engine code written by mail.
>
You have an explicit prohibition from the original author of the game engine code written by mail.

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Post by dave » Wed Aug 11, 2010 5:48 am

>You have an explicit prohibition from the original author of the game engine code written by mail.
>
>... back on topic:
>
i see you do not understand. this means:
you are not allowed to use the software.
please remove it from your product! thankyou!

ncrecc
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Re: License of Emerald Mine game engine

Post by ncrecc » Sun Jan 06, 2019 4:26 am

Bump, was this ever resolved outside of the forums? >8 years... I know, but it's concerning that there was never really a solid conclusion to this dispute. From what I understand, Holger took this guy's Emerald Mine engine, directly translated it into C, and put it into RnD when the author explicitly stated he wasn't okay with it. :? Is there some context outside of this thread and the "Emerald Mine Club - no such thing as wrap-around movement?" thread that I'm missing? Am I misinterpreting anything here?

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Holger
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Re: License of Emerald Mine game engine

Post by Holger » Sun Jan 06, 2019 5:36 pm

was this ever resolved outside of the forums?
Unfortunately, no, although I tried hard over the years.
From what I understand, Holger took this guy's Emerald Mine engine, directly translated it into C, and put it into RnD when the author explicitly stated he wasn't okay with it.
No, this was not the case.

Instead, I found the code for "Emerald Mine for X11", but wasn't able to contact the author for some time. Then I used it in R'n'D, knowing that it would be possible that the author would show up later and tell me that this is not OK. Fortunately, this did not happen, but instead, I got mail from the author some day where he told me that there is a new version of his game engine available now which I might want to use instead. Now finally having contact with the original author, I took the opportunity to ask for permission for using his code in my game. Here is an extract from our mail correspondence from April 2007 regarding this:

Code: Select all

>> A few years ago, when I started with the integration of the native
>> EMC engine into Rocks'n'Diamonds, I tried to contact you, but never
>> got any mail reply because those mail addresses I found by Google
>> seemed to be outdated. :-o
> 
> Ah yeah i left the 'net for a while as my computer blew up :)
> only towards the end of last year did i manage to recover my old code.
> 
>> I mainly wanted to ask for permission to use your code in my game,
>> and also had some technical questions about the game engine itself.
> 
> yeah no problems, it's under the BSD license.
This was followed by a number of updates of his game engine code, each containing a BSD style license now (while the game engine code i used in the first place did not contain a license file).

Then, about two years later (2009), things changed, and got complicated, and I can only guess why -- accusations were that I did changes to the game engine code that he did not like (like changed code formatting and changes to the game logic). He requested to use his latest code (publicly released under a BSD style license), but without changing the code -- a request (or wish) which he is free to express, of course, but that would not be enforced by the license he chose for his code. As I told him that I wanted to keep some of the changes I did for the game engine integration in R'n'D, he deliberately changed the license in subsequent releases of his game engine code in 2010 to a more restrictive (old style) 4-clause BSD style license, which is not compatible with the GPL license R'n'D is released under (while the previously used (common) 3-clause BSD style license is GPL compatible), to prevent me from using his latest code in my program. But this not being enough, he told me that this also retroactively changes the licenses for all existing releases of his code, so the issue boils down to the question what happens if the license for a piece of code is changed -- does it only affect new releases of the code, or does it also affect already released versions of the code? As far as I can see (using Google), by far the vast majority of people (also speaking of lawyers here) in the open source area do take the stand of this (retroactively changing the license of already released code) not being possible, but instead simply causing the code to fork (then having different versions of the code with different licenses).

Because of this dispute, I stopped work on the EMC game engine for many years, although I thought recently that I maybe should update the EMC game engine using the last version of the code of "Emerald Mine for X11" that still contains the common (GPL compatible) 3-clause BSD style license, while not using the more recent versions using the (GPL incompatible) 4-clause BSD style license.

I hope this clarifies things a bit regarding this issue.

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Re: License of Emerald Mine game engine

Post by dt1 » Sat Nov 23, 2019 11:42 pm

He had used my software without permission or attribution for many years, and when I found out it was happening, I sent him an email.
At first I was sympathetic and said he could use it, however, when I looked closer, i found that he had introduced bugs into the game logic, and when i told him that the game logic must not be changed, he just argued with me, and told me he didn't have to respect that.
Using my correct, unmodified game logic was an additional condition of use, but he ignored me, and argued that it did not matter to him because the license didn't say so.
If he had restored the original game logic, I would have been happy to let him use it.
But he had introduced bugs, and he refused to undo his changes, so I changed my mind.
So I said, both in email and on this forum, that i withdraw his license, and that he is forbidden to use any of my software.
(Note this applies only to Holger Schemel, I don't mind if other people use my code).
Here is the code: http://www.emeraldmines.net/?emeraldx11

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Holger
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Re: License of Emerald Mine game engine

Post by Holger » Tue Dec 10, 2019 10:05 pm

If you want to forbid certain things regarding your code, why did you choose a license that explicitly allows it?

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