[1.7.2] Spawner types not matching vanilla Minecraft

[KeepOnDigging]

I am seeing unexpected behaviour when running Forge. Spawners in dungeons are different types to the spawner in that location in a world with the same seed in Vanilla Minecraft.

 

For example, start a creative world in Vanilla with the seed 35267400.

 

/tp -238 52 389

This is a Zombie spawner.

 

Start a new world with the same seed with Forge installed, no other mods required.

/tp -238 52 389

This is now a skeleton spawner.

 

I can't see any consistency with the changes in spawners:

 

Coordinates          Vanilla  Forge

/tp -238 52 389 - zombie  skelly

/tp -143 39 110 - spider    zombie

/tp -118 29 398 - zombie  zombie

/tp -177 25 431 - zombie  skelly

/tp -481 53 517 - zombie  spider

/tp -451 50 539 - skelly    zombie

/tp -534 39 616 - skelly    zombie

/tp -524 33 548 - skelly    spider

 

The behaviour I expect is for the spawners to be the same type in both vanilla Minecraft and with Forge installed.

 

I have confirmed this behaviour on Mac with Forge 10.12.0.1023 and also Forge 10.12.0.1029.

 

Thanks for all your great work on Forge!

KeepOnDigging.

 

[LexManos]

I'll look into it, but these types of world gen stuff are extreamly finnickey, as they are based of a Random Number Generator that has to be polled the exact correct number of times to get things to match up. So if a mod is added that polls the RNG it'll throw off everything after it.

If you're saying this is JUST forge installed, I will take a look see if I can find where the extra polls are coming from when I get back into town.

[KeepOnDigging]

Yes, I only have Forge loaded.

 

Minecraft Forge 10.12.0.1029

3 mods loaded, 3 mods active.

 

Thanks for looking into this LexManos!

 

KeepOnDigging.

[KeepOnDigging]

I have just confirmed that this problem still exists with Forge 10.12.1.1061.

 

I have installed just Minecraft 1.7.2, Forge and no other mods.

 

KeepOnDigging.