How was Forge created, as well as others?

[jonathanpecany 0]

So, I have a question that is really bugging me a lot, but how was things such as Forge, Bukkit, Spigot, Optifine, etc created. Like what kind of resources did they use, did they use a Minecraft API or something, how did they manage to make it so the Minecraft launcher can detect it and run it. I kind of wanted to create my own someday but I don't know where to start, and I know I could ask when I wanna start but this question just really bugs me.

=== Skip this passage if you don't wanna know why I asked on Forge forums ===
I know I could also ask on other forum websites, like Minecraft Forums and Bukkit forums but Minecraft Forums is pretty much dead and/or dead to me and people on Bukkit don't get to the point well enough, but I asked here since Forge is a part of my question, it is quite active, and people manage to get to the point when answer, as well as nice...well, kind of nice...okay, some people on here are a bit rude, but at least they get to the point. So that is why I am asking here. I just typed this part so you guys don't ask about other forums, just in case since I am talking about other things as well. And if you are about to recommend another forum, don't, any other ones, I won't truly know about and would rather not use any recommendation, too much work to ask a simple (Maybe complex) question.
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Any intel, documentation, etc, please share. I do know quite a bit of Java, so I will understand documentations and such. So just any intel you got, it will also be very nice if a Forge developer answered as well, like very nice as I know they will have an answer. I won't accept an indirect answer however, so I need some sort of sources, documentation, or/and examples. Hopefully this all

Edited November 26, 2020 by jonathanpecany

[diesieben07 7590]

Forge uses a large set of tools, all the necessary ones are open source as far as I know: https://github.com/MinecraftForge/

 

There is no "MinecraftAPI", Minecraft is closed source and obfuscated. The rough process for development is this:

1. Download Minecraft.
2. Run it through a decompiler.
3. Fix any decompilation issues.
4. Rename the obfuscated names to something readable.

Forge then uses a patching system to change the necessary part of the Minecraft code. During development these work on the source code level (changes in .java files), but at runtime they will be applied as binary patches to the .class files. To do this, Forge uses a custom class loader, which can transform any class as it is being loaded.

 

As for how the launcher knows how to launch forge: The Minecraft launcher is configured through .json files in the versions folder. The Forge installer creates one.

[jonathanpecany 0]

10 hours ago, diesieben07 said:

Forge uses a large set of tools, all the necessary ones are open source as far as I know: https://github.com/MinecraftForge/

 

There is no "MinecraftAPI", Minecraft is closed source and obfuscated. The rough process for development is this:

1. Download Minecraft.
2. Run it through a decompiler.
3. Fix any decompilation issues.
4. Rename the obfuscated names to something readable.

Forge then uses a patching system to change the necessary part of the Minecraft code. During development these work on the source code level (changes in .java files), but at runtime they will be applied as binary patches to the .class files. To do this, Forge uses a custom class loader, which can transform any class as it is being loaded.

 

As for how the launcher knows how to launch forge: The Minecraft launcher is configured through .json files in the versions folder. The Forge installer creates one.

Thanks, and I can see the long process, how long did it take to create it.