How would I make a gravity system that the player can turn on and off? The gravity system includes walking on the roof, jumping on the roof, etc. You can't do this by just adding upwards velocity to the player, because then they don't run as fast or jump at all.

 

Thanks in advance!

That will require a lot of work with ASM, as vanilla doesn't have a concept of gravity. It knows about downward acceleration and whether or not an entity needs it (aka "grounded").

What is ASM?

Thanks

 

So 1. Why do I need a core mod? 2. How do I make one? 3. What difference does it make?

coremods allow u to change actual vanilla code. which can be a pain in the ass and should ONLY be done if u are seriously experienced in java

How would I use coremods to make a gravity system?

 

And how do I start a core mod

I am sorry but.. If u are asking this u are most likely not able to pull it off.

Everyone has to start somewhere...

somewhere is learning java, somewhere is learning basic modding, somewhere is NOT a coremod

I know java and basic modding, I'm talking about starting somewhere with a cored because I've never done one before

That's not a good reason.  Coremods are [Expert+++] level things.  It requires a deep understanding of the Java bytecode and the ASM library.