Entities that tick in nether portal for one gametick don't get sent to the nether

Please fix this is very annoying.

I can say the bug is still there for snapshot 20w27a. Can anyone else confirm it as I am the bug poster.

(Disclaimer: 20w28a reduces the time by 1 more gt than previous versions as int I (this.netherPortalTime) is equal to 0)

The problem:

This code analysis is using Yarn mappings for 1.16.1.

This is very dry and a long explanation so that most people who aren't that code savy can understand it.

Below is the reason why the current game can't send an entity into the nether in one gametick via a portal.

For this example, I will only be using LivingEntities (a pig).

When the pig is ticked for the gametick, it calls the LivingEntity tick().

// @Override
public void tick() {
    super.tick();
    //cutting off lines between the two methods
    this.tickMovement();
    //cutting off as the rest is not needed....

    }
}

As shown, it will first preform the super.tick() then the this.tickMovement() which contains the movement of the pig in the entity class after a few more method calls. This movement is needed to do block collisions in order to say it is in a portal.

So let's explore the super.tick()

public void tick() {
    if (!this.world.isClient) {
        this.setFlag(6, this.isGlowing());
    }
    this.baseTick();
}

From the tick(), it calls the this.basetick() method which will contain some important code involving portals, so let's now look at the base tick.

public void baseTick() {
     //cutting off lines above as they are not needed
    this.tickNetherPortal();
    //cutting off as the rest is not needed....
}

In the base tick, it calls the this.tickNetherPortal() method, which is a very important method in this exploration.

protected void tickNetherPortal() {
    //removed some lines above as not needed
    int i = this.getMaxNetherPortalTime();
    //removed some lines above as not needed
    if (this.inNetherPortal) {
        //removed some lines above as not needed
        if (lv3 != null && minecraftServer.isNetherAllowed() && !this.hasVehicle() && this.netherPortalTime++ >= i) {
            this.world.getProfiler().push("portal");
            this.netherPortalTime = i;
            this.netherPortalCooldown = this.getDefaultNetherPortalCooldown();
            this.changeDimension(lv3);
            this.world.getProfiler().pop();
        }
        //removed some lines above as not needed
}

The first important thing to look at here is the this.inNetherPortal(). For this statement to be true, it must first collide with a portal via some move method/block collision. 

As the move method of entities (velocity), that is called in the LivingEntity, is after the super.tick() (aka the tickNetherPortal()), the pig can't pass this first statement, thus can't end up in the nether on the same tick it moves.

However, it gets worse....

Let's now look at this.netherPortalTime. This.netherPortalTime can only increase via an entering into the 

if (lv3 != null && minecraftServer.isNetherAllowed() && !this.hasVehicle() && this.netherPortalTime++ >= i)

if statement, which means it first needs to be in a nether portal. So in most cases, the pig's movement will have to collide with a portal first, then wait another tick just to be able to hit that if statement.

Now, once that if statement is called once, it will need to be called again as the first time it is called, this.netherPortalTime is equal to 0 and thus fails the check as i is 1. After the first calling of the if, the value is now 1 due to the this.netherPortalTime++, which means it can complete the if statement once it ticks again.

So, by looking at the code, it takes 3 ticks for a pig to enter the nether via normal means.

A potential fix to make it enter in the same tick it moves:

So, a potential fix would be to first move the this.tickNetherPortal() out of the super.tick() and place it after the movement of the different entities types. Once that is done, the this.netherPortalTime is not needed for most none player entities so it can be zero for most. This means that the entity would move, collide with a portal, and then tick the portal and get sent to the nether all in the same tick.

I have been waiting for this bug to be fixed since 1.12! Amen

Still not working in 20w28a; however, the ticking has been reduced by 1 gt as of testing. I will add the new code changed when the mappings come out.

Seems to not work in 20w29a. Still same as 20w28a.

Seems to not work in 20w30a. Still same as 20w28/29a.

I have marked this issue as fixed because:

• If an entity is in a portal at the end of a tick, it will be teleported in the next tick.

• The entity only has to be touching the portal for 1 tick.

I believe this issue was originally about a problem where an entity had to be touching a portal for more than one tick to be teleported. That bug is fixed.

There are still some issues that could be raised separately, with more specific repro steps:

1. If an entity is in a portal in a non-entity processing chunk, it will not teleport.

2. If an entity is moving fast, it can pass right through a portal without ever touching it and will not teleport (MC-196556)

3. Entities teleport though portals at the start of a tick (before they move) instead of at the end of a tick (after they move)

This bug report was to address a few issues that caused an entity to not be sent to the nether in one gametick. That is why I was going for this title "Entities that tick in nether portal for one gametick don't get sent to the nether".

1. The first issues was that it took around 3 ticks for the entity to be sent to the nether pre-28a.

2. That the move method is after portal so that entity could never be sent to the nether in the same game-tick that is arrived in it. (This would also solve the "If an entity is in a portal in a non-ticking chunk, it will not teleport." unless they were piston pushed in or some other move call.)

The reproducing steps of this bug report also work with "Entities teleport though portals at the start of a tick (before they move) instead of at the end of a tick (after they move)" suggestion as the original bug report covered both of the issues that made one action not possible.

If you think that "Entities teleport though portals at the start of a tick (before they move) instead of at the end of a tick (after they move)" should be a separate ticket after this address I will do so.

Edit: I created a bug report based on your third suggestion MC-196897

why did you create a different bug report, not the one suggested?