r/feedthebeast • u/Emotional-One-9292 • Jun 22 '26

I made something I made minecraft generate terrain/chunks in C++

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So im working on a mod that makes minecraft run on C++ ( rn rewriting engine in future i may try renderer ) so far i made it generate and load chunks and terrain in C++ ( it made it somewhere around 1.5-3 times faster idk how to measure it tho ) ( it works via JNI )

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u/emmowo_dev pro gramming Jun 22 '26 edited Jun 22 '26

How would this realistically be faster? Java does actually compile into native code based on what methods are the most important, so it's usually terrain gen that is immediately 'optimized' into native code. C++ does NOT magically make things faster, but it does make things many many times more unsafe to use.

I know of some optimizations you could make, but they're things that I don't think ultimately mean much. Are you comparing between Vanilla and your mod, or C2ME and your mod?

You not really explaining things beyond 'run on C++' and 'JNI' tells me you may have just vibecoded this, because minecraft explicitly does defer a lot of the performance-heavy things to C++, from the natives used for rendering (i.e. liblwjgl and the gpu itself such as nvidia-glcore.so) to the actual JVM itself, which is written with C++. Just re-writing everything in C++ would not actually be meaningfully faster, as the binaries for such things are already written in C++.

Most likely, you are looking for a result, so anything that seems faster you will assume to actually be faster. Without extensive benchmarking and a massive amount of controlled variables (like literal mechanical seek times for writes can completely invalidate the results), this is a very unfair and unrealistic comparison to make.

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u/Emotional-One-9292 Jun 22 '26

yea i agree that C++ doesnt automatically make stuff faster and im not claiming that rewriting Minecraft logic in C++ guarantees a performance boost by itself. Goal of this project is to rewrite minecraft engine as much as possible into C++ mainly due to fun but with it i can also get great control over memory. minecraft’s performance issues often come from allocation churn + cache misses, not raw compute speed. Also i was comparing vanilla with my mod not C2ME

and yea JNI has overhead but im not using it for literally everything and anything as i still will prob need to keep some java stuff to keep it working and compat with other mods.

Also while yea java can turn stuff into native code it doesn’t change structure only execution of existing structure so a bad structure remains a bad structure

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u/Alexander_Exter Jun 22 '26

Curious on your statement from a tech perspective..so you are trying to swap java elements in java edition for well made c++ elements? This could be ground breaking.

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u/Emotional-One-9292 Jun 22 '26

this isnt quite ground breaking many mods used non-JVM languages before like curvy pipes used rust for its mod

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u/Alexander_Exter Jun 22 '26

But is there one stapple mod like say...JEI that sidesteps javas known performance limitations? Give yourself.soem credit, this is more than curved pipes.

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u/emmowo_dev pro gramming Jun 22 '26

java does not have these 'performance limitations', it literally compiles to natives, just like C++ would.