[1.15] changing AttributeModifier of item with keypress at runtime

[simplebunsen]

So I want to have an item that has Jump Boost when equipped (already working), and I want the movement speed to be faster in the air. Therefore, I want to change the Attribute Modifiers of my ArmorItem programatically, and at runtime.

The code below doesn't produce the expected outcome of only applying the speedup when the player holds the space key, instead it only even seems to fire if I hover directly on the item in my armor slot, pressing the space bar.

public class JumpBootsItem extends ArmorItem {

    private AttributeModifier movementSpeed = new AttributeModifier("JumpBootsMovementSpeedModifier", 1, Operation.MULTIPLY_TOTAL);
    public Minecraft mc = Minecraft.getInstance();

    @Override
    public Multimap<String, AttributeModifier> getAttributeModifiers(EquipmentSlotType slot, ItemStack stack) {
        Multimap<String, AttributeModifier> output = super.getAttributeModifiers(slot, stack);
        if (slot == EquipmentSlotType.FEET && stack.getItem().equals(this) && InputMappings.isKeyDown(mc.getMainWindow().getHandle(), mc.gameSettings.keyBindJump.getKey().getKeyCode())) {
            output.put(SharedMonsterAttributes.MOVEMENT_SPEED.getName(), this.movementSpeed);
            LOGGER.fatal("I am holding jump, speed should change");
        }
        return output;
    }

How to actually implement what I'm trying to do? Should I maybe instead try to simply add a "clone" of the item with the speed boost applied, then silently change it in the armor slot once the space bar is pressed?

Thanks for replies!

Edited June 6, 2020 by simplebunsen

[Novârch]

8 minutes ago, simplebunsen said:

once the space bar is pressed

Why don't you use Entity#isAirborne? Also, you should use this to get if a keybind is pressed, Minecraft#gameSetiings#"insert keybind here"#isPressed.

Edited June 6, 2020 by Novârch

[simplebunsen]

2 minutes ago, Novârch said:

Why don't you use Entity#isAirborne? Also, you should use this to get if a keybind is pressed, Minecraft#gameSetiings#"insert keybind here"#isPressed.

Thanks for replying, I wanted to use space bar so the player had agency over whether or not he actually wanted to continue jumping and receiving faster movement. I will use the second suggestion, but really that's beside the point as the problem I'm having concerns the AttributeModifier not changing properly. Do you know anything about that?

[simplebunsen]

2 minutes ago, diesieben07 said:

First of all, you are reaching across logical sides. getAttributeModifiers will also be called on the server, which has no idea what key bindings are (it doesn't even have a keyboard...).

You will have to check LivingEntity#isJumping on the player, which requires reflection because it's protected. But it will be available on server and client.

 

Then you need to use PlayerTickEvent (make sure to check TickEvent#phase) to apply the modifier, because Item#getAttributeModifiers is only checked when the item changes.

Thanks for answering, I will try to implement this with my limited knowledge ?

Would it be sufficient to apply the modifier in the onArmorTick class, since it only really needs to be checked when I have the armor on.

Also, how to apply the modifier? Should I put and remove from the Multimap provided by getAttributeModifiers?

[simplebunsen]

56 minutes ago, diesieben07 said:

No, you would not be able to remove it then because as soon as the armor is removed, that method is no longer called.

 

No, you have to apply it directly to the player. Look how the item's modifiers (i.e. Item#getAttributeModifiers) is handled in LivingEntity#tick.

Okay, understand the first point. Looking into attributes now

[simplebunsen]

2 hours ago, diesieben07 said:

No, you would not be able to remove it then because as soon as the armor is removed, that method is no longer called.

 

No, you have to apply it directly to the player. Look how the item's modifiers (i.e. Item#getAttributeModifiers) is handled in LivingEntity#tick.

So I went to solve the problem using the Modifiers.. Firstly I have no clue how to do Reflections, I'm not a Java Master yet ? So I used onGround.

    public void onArmorTick(ItemStack stack, World world, PlayerEntity player) {
        player.addPotionEffect(new EffectInstance(Effects.JUMP_BOOST, 0, 4, false, false, false));

        if (!player.getAttribute(SharedMonsterAttributes.MOVEMENT_SPEED).hasModifier(movementSpeed)) {
            if (slot == EquipmentSlotType.FEET && stack.getItem() == this && !player.onGround) { 
                player.getAttribute(SharedMonsterAttributes.MOVEMENT_SPEED).applyModifier(movementSpeed);
                LOGGER.fatal("I am NOT ON GROUND, speed should and has change");
              //SPEED is applied (two times in game, maybe due to lack of checks for sidedness? how to do?)
            }
        }

    }

    @SubscribeEvent
    public static void onTickEvent(TickEvent.PlayerTickEvent event) {
      
        if (event.player.onGround && event.player.getAttribute(SharedMonsterAttributes.MOVEMENT_SPEED).hasModifier(movementSpeed)){
            event.player.getAttribute(SharedMonsterAttributes.MOVEMENT_SPEED).removeModifier(movementSpeed);
            LOGGER.fatal("Stopped being in the air etc, speed back to normal");
        }
    }

No idea what I'm doing wrong, could you give me some pointers yet again, please?

[simplebunsen]

Just now, diesieben07 said:

Whats the problem?

I really forgot it huh ?‍♂️

Well it applies the effect more or less as expected on jumping, but the other thing doesn't take it away again at all.

This all is in the class

public class JumpBootsItem extends ArmorItem

which is added to the forge event bus in the main mod method. Not sure if that's relevant.

[simplebunsen]

Just now, diesieben07 said:

Is your event handler called at all?
Also you are not checking TickEvent#phase.

the method itself seems to be called, as it logs something every tick if I put in a logger.

I don't know what the phase method is about, and I can't find any informative docs on it.

[simplebunsen]

13 hours ago, diesieben07 said:

Well, I can't see the issue by just staring at the code, sorry.

very weird... I ended up just applying a speed effect, but I don't have as precise control over the factor there.

Thanks for trying to help, anyways!