Player velocities being weird

[Chixen]

I'm trying to set the player y velocity to 1 whenever the player hits the ground, but for some reason it's only working when the player takes damage. Anyone know how to combat this? I did some debug testing and found out that the LivingFallEvent is activating twice or more when I hit the ground, for some reason.

Edited May 18, 2021 by Chixen
further clarification

[ChampionAsh5357]

Where are you setting this information? How are you setting it? When are you setting it?

45 minutes ago, Chixen said:

I did some debug testing and found out that the LivingFallEvent is activating twice or more when I hit the ground, for some reason.

Makes sense since it's called on both logical sides.

[Chixen]

On 5/17/2021 at 11:54 PM, ChampionAsh5357 said:

Where are you setting this information? How are you setting it? When are you setting it?

public class EventHandler {
    @SubscribeEvent
    public static void land(final LivingFallEvent event) {
        if(!event.getEntity().isSuppressingBounce()) {
            event.getEntity().setDeltaMovement(event.getEntity().getDeltaMovement().multiply(0.0, -1.0, 0.0));
            event.setDamageMultiplier(0);
        }
    }
}

Here's my code, but It's not doing anything.
 

[Draco18s]

How are you registering your EventHandler class with the event bus?

[ChampionAsh5357]

This has to do with very specific circumstances I think. From what I can gather in the codebase, when the fall event occurs, it's near the end of the handling method. As such, the movement wouldn't be applied until the next available tick. However, the player was marked as being on the ground and the jump button not being pressed. That ends up taking precedence and saying, "hey, don't increase the velocity, nothing happened". A special case is when the player takes damage though. A flag gets set to allow the knockback to be applied which takes priority over the being on the ground. As such, the player is knocked into the air since it just takes a sample of the set delta movement.

Falling on a block is a different matter as this is called during the Entity#move method after all replacement logic on the delta movement has been applied. This allows the block to do whatever to the delta movement.

I apologize for any inaccuracies in this assessment.

Edited May 21, 2021 by ChampionAsh5357
Inaccurate, look at dies' comment

[Chixen]

I've been looking at this for a while and still can't get a fix for it? can someone help me on the right track?

[Chixen]

On 5/21/2021 at 2:38 AM, diesieben07 said:

Player velocity and movement is controlled client side only. There is one specific case in which the server updates the client velocity, there is a flag for it on the server. If it is set, the server will send a velocity update packet to the client at the end of the tick. And guess what, that flag is set when you take damage (this is why it works when the player takes damage).

You can set this flag yourself: player.hurtMarked = true

I tried this, but now it's making me only go up a little bit, instead of the regular amount. new code below:
 

public class EventHandler {
	@SubscribeEvent
	public static void land(final LivingFallEvent event) {
		if(!event.getEntity().isSuppressingBounce()) {
	    	Vector3d vel = event.getEntity().getDeltaMovement();
			System.out.printf("%-11s %-11s %-11s\n", vel.x, vel.y, vel.z);
		    if (vel.y < 0.0) {
		    	double d = event.getEntity() instanceof LivingEntity ? 1.0 : 0.8;
		    	System.out.printf("%7.3f\n",d);
		    	event.getEntity().setDeltaMovement(vel.x, -vel.y * d, vel.z);
		    	event.getEntity().hurtMarked = false;
		    	event.getEntity().hurtMarked = true;
		    }
			event.setDamageMultiplier(0);
	    	vel = event.getEntity().getDeltaMovement();
			System.out.printf("%-11s %-11s %-11s\n------------\n", vel.x, vel.y, vel.z);
		}
	}
}

here's the result after jumping a few times (and flinging myself into the air)
 

------------
0.0         -1.137319364784352 0.0        
  1.000
0.0         1.137319364784352 0.0        
------------
0.0         -0.9889821903010232 0.0        
  1.000
0.0         0.9889821903010232 0.0        
------------
0.0         -0.0784000015258789 0.0        
  1.000
0.0         0.0784000015258789 0.0        
------------
0.0         -0.4448259643949201 0.0        
  1.000
0.0         0.4448259643949201 0.0        
------------
0.0         -0.1552320045166016 0.0        
  1.000
0.0         0.1552320045166016 0.0        
------------
0.0         -0.16123445549844412 0.0        
  1.000
0.0         0.16123445549844412 0.0        
------------
0.0         -0.0784000015258789 0.0        
  1.000
0.0         0.0784000015258789 0.0        
------------

It also seems like sometimes it's bouncing me multiple times but still not the normal amount.

 

EDIT: I should clarify that this is very close to the vanilla minecraft code of the bounceUp() method of the SlimeBlock class.
 

private void bounceUp(Entity entity) {
        Vec3 vec3 = entity.getDeltaMovement();
        if (vec3.y < 0.0) {
            double d = entity instanceof LivingEntity ? 1.0 : 0.8;
            entity.setDeltaMovement(vec3.x, -vec3.y * d, vec3.z);
        }
    }

 

Edited May 22, 2021 by Chixen

[Chixen]

bump because I really need help with this.