[MC-48923] Slime/magma cubes not affected by jump boost potion effect

The bug

Slimes and magma cubes do not jump higher with the Jump Boost effect, although it still reduces fall damage for Slimes.

Steps to reproduce

Spawn Slime

Run command

/effect give @e[type=slime] minecraft:jump_boost 60 10 false

Now you should see the particle effect, but the slime doesn't jump higher than normal.

For example see attached video or http://youtu.be/Upb30KUOVCM

Code analysis

Code analysis can be found in this comment.

Linked issues

is duplicated by 3

MC-73296 Slime mob not effected by the jump potion effect Resolved

MC-96808 Slimes don't react to jump_boost effect Resolved

MC-162763 Slimes Unaffected by Jump Boost Resolved

relates to 4

MC-121788 Jump boost, slow falling and levitation don't apply to ridden horses, pigs or striders until after a relog Resolved

MC-60229 Mob AI don't use Jump Boost Resolved

MC-266494 Jump Boost does not affect the breeze's jump Resolved

MCPE-54294 Jump boost has no effect on magma cubes Resolved

Attachments

MC-48923.mp4

mcrft-2014-02-17-13-44-29.mp4

Comments 40

s7%6maTt4wC$JQ8* 2014-02-19T15:39:59Z

I really hope this gets fixed, I need it for my map...

Itouch2 2014-02-21T22:24:12Z

Confirmed

Itouch2 2014-03-12T12:11:18Z

Confirmed for 14w08a and 14w10c

galaxy_2alex 2014-08-21T14:01:39Z

Is this still a concern in the current Minecraft version 14w32d / Launcher version 1.5.2 or later? If so, please update the affected versions in order to best aid Mojang ensuring bugs are still valid in the latest releases/pre-releases.

Markus Wersig 2014-08-21T15:36:23Z

Tested it in 14w34d. Slimes still don't jump higher with Jump boost effect applied.

30 more comments

Avoma 2021-12-15T17:04:37Z

Can confirm in 1.18.1.

Avoma 2022-03-20T12:16:29Z

Can confirm in 1.18.2 and 22w11a.

Avoma 2022-06-13T12:25:52Z

Can confirm in 1.19.

Avoma 2022-08-17T14:14:59Z

Can confirm in 1.19.2.

ampolive 2022-10-29T00:52:06Z

Code analysis (Mojang mappings, 1.19.2): the code for checking the Jump Boost effect is in LivingEntity#jumpFromGround(), which slimes (and magma cubes) override in their respective classes. In Slime#jumpFromGround(), instead of

Vec3 $$0 = this.getDeltaMovement();
this.setDeltaMovement($$0.x, this.getJumpPower(), $$0.z);

it should be

Vec3 $$0 = this.getDeltaMovement();
this.setDeltaMovement($$0.x, this.getJumpPower() + this.getJumpBoostPower(), $$0.z);

For magma cubes, it is a bit more complicated, because I am unsure if the jump boost should be scaled with the magma cube's size or not. But it should be an analogous fix.