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[1.8.9][Packet/GUI] Creating a custom merchant : packet to pass entity to gui ?


Major Squirrel

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Good evening guys,

 

I'm currently trying to create a custom EntityMerchant. Basically, it works the same as the EntityVillager from Minecraft, except that I want to control all the transactions for each merchant (from a DB for example).

 

My entity is currently created, its name is Timmy (yes), and I can't figure out how I could pass the entityId to a gui triggered from server side, so that I can get an Entity object once the gui is open. I took a look at the EntityVillager code : when interacting with the Entity, it displays the villager trade gui passing the Entity (as this) :

 

    /**
     * Called when a player interacts with a mob. e.g. gets milk from a cow, gets into the saddle on a pig.
     */
    public boolean interact(EntityPlayer player)
    {
        ItemStack itemstack = player.inventory.getCurrentItem();
        boolean flag = itemstack != null && itemstack.getItem() == Items.spawn_egg;

        if (!flag && this.isEntityAlive() && !this.isTrading() && !this.isChild() && !player.isSneaking())
        {
            if (!this.worldObj.isRemote && (this.buyingList == null || this.buyingList.size() > 0))
            {
                this.setCustomer(player);
                player.displayVillagerTradeGui(this);
            }

            player.triggerAchievement(StatList.timesTalkedToVillagerStat);
            return true;
        }
        else
        {
            return super.interact(player);
        }
    }

 

Looking more closely at the code, it seems that a S2DPacketOpenWindow packet is sent. The thing that I don't understand is the way I could possibly do the same (or the entityId), using Forge GuiHandler. Sending a packet ? Why not, but what after then ?

 

Furthermore, LexManos shared a trick to pass the entityId through an int (can't find the topic) in the getServerGuiElement method from GuiHandler, but I still don't know what to do next. It is some kind of missunderstanding here that I would like to kill.

 

Thank you for your time and you help. :)

Squirrel ! Squirrel ! Squirrel !

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To clarify, instead of using #displayVillagerTradeGui, use #openGui and pass the entity ID as one of the last 3 parameters.

 

The last 3 parameters are all ints and are typically used for TileEntity coordinates, but if your GUI is not using a TE, you can use those parameters for anything you want such as the entity ID.

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Thank you guys.

 

Yet, something bugs me : what would be the interest to go through a packet to open a gui instead of opening it directly ?

In my case, I can avoid using a packet to open the gui, since I can directly pass the entity id in the openGui method.

 

I saw few posts on this forum that advise to use packet to open gui.

 

giphy.gif

Squirrel ! Squirrel ! Squirrel !

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If you do stuff on client - server doesn't know about it. Even if you'd send packet telling server that you did something, server might not really "accept it" - meaning: client opens gui, sends packet with request but on server it happens that "you are not allowed to open the gui right now", but its alredy opened on client - boom, not desired outcome. (same goes with interaction - since client only has "predicted" server values, some things might be true on client and false on server).

 

I for one always code stuff in order: client -> req -> server decides -> packet (or GuiHandler call) -> client does stuff server tells.

 

All in all - is depends on what you need and if server needs to know what you do. You can even open gui directly from Minecraft class.

 

Mind that if client alredy has values that need to be displayed on gui and server doesnt need to know shit, you are free to operate on client only. E.g: Display player stats from IEEP/Capabilities which you KNOW are always synced.

1.7.10 is no longer supported by forge, you are on your own.

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If you do stuff on client - server doesn't know about it. Even if you'd send packet telling server that you did something, server might not really "accept it" - meaning: client opens gui, sends packet with request but on server it happens that "you are not allowed to open the gui right now", but its alredy opened on client - boom, not desired outcome. (same goes with interaction - since client only has "predicted" server values, some things might be true on client and false on server).

 

I for one always code stuff in order: client -> req -> server decides -> packet (or GuiHandler call) -> client does stuff server tells.

 

All in all - is depends on what you need and if server needs to know what you do. You can even open gui directly from Minecraft class.

 

Mind that if client alredy has values that need to be displayed on gui and server doesnt need to know shit, you are free to operate on client only. E.g: Display player stats from IEEP/Capabilities which you KNOW are always synced.

 

Ok so if I follow your way of coding in order, in my case it would be :

 

Client right clicks on entity --> sends a packet that will be handle to the server --> server decides whether or not to let the client open the gui --> (admitting yes) call openGui method

 

In there, the packet will just be useful to do some "tests" or requirements before deciding to open the gui or not ?

Squirrel ! Squirrel ! Squirrel !

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If you do stuff on client - server doesn't know about it. Even if you'd send packet telling server that you did something, server might not really "accept it" - meaning: client opens gui, sends packet with request but on server it happens that "you are not allowed to open the gui right now", but its alredy opened on client - boom, not desired outcome. (same goes with interaction - since client only has "predicted" server values, some things might be true on client and false on server).

 

I for one always code stuff in order: client -> req -> server decides -> packet (or GuiHandler call) -> client does stuff server tells.

 

All in all - is depends on what you need and if server needs to know what you do. You can even open gui directly from Minecraft class.

 

Mind that if client alredy has values that need to be displayed on gui and server doesnt need to know shit, you are free to operate on client only. E.g: Display player stats from IEEP/Capabilities which you KNOW are always synced.

 

Ok so if I follow your way of coding in order, in my case it would be :

 

Client right clicks on entity --> sends a packet that will be handle to the server --> server decides whether or not to let the client open the gui --> (admitting yes) call openGui method

 

In there, the packet will just be useful to do some "tests" or requirements before deciding to open the gui or not ?

 

When the player right clicks on an entity, the client sends a packet to the server and then calls the entity's interaction method (this actually happens up to twice, once for

Entity#interactAt

and once for

Entity#interactFirst

; the second packet and call only happen if the first returned

false

). This happens in

Minecraft#rightClickMouse

 

When the server receives these packets, it first checks that the entity exists and the player is close enough to interact with it. If these conditions are met, it calls the interaction method that the packet was sent for. This happens in

NetHandlerPlayServer#processUseEntity

.

 

You should open your GUI from the server-side call of

EntityLiving#interact

(called from

Entity#interactFirst

), i.e. when

world.isRemote

is

false

.

Please don't PM me to ask for help. Asking your question in a public thread preserves it for people who are having the same problem in the future.

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When the player right clicks on an entity, the client sends a packet to the server and then calls the entity's interaction method (this actually happens up to twice, once for

Entity#interactAt

and once for

Entity#interactFirst

; the second packet and call only happen if the first returned

false

). This happens in

Minecraft#rightClickMouse

 

When the server receives these packets, it first checks that the entity exists and the player is close enough to interact with it. If these conditions are met, it calls the interaction method that the packet was sent for. This happens in

NetHandlerPlayServer#processUseEntity

.

 

You should open your GUI from the server-side call of

EntityLiving#interact

(called from

Entity#interactFirst

), i.e. when

world.isRemote

is

false

.

 

Actually, I do this :

 

    @Override
    protected boolean       interact(EntityPlayer player) {
        ItemStack           itemstack = player.inventory.getCurrentItem();
        boolean             flag = itemstack != null && itemstack.getItem() == Items.spawn_egg;
        boolean             flag2 = itemstack != null && itemstack.getItem() == Items.name_tag;

        if (this.isEntityAlive() && !player.isSneaking()) {
            if (this.worldObj.isRemote) {
                player.openGui(Main.instance, Reference.GuiIdentifiers.GUI_MERCHANT, this.worldObj, this.getEntityId(), 0, 0);
            }
            return (true);
        } else if (flag && player.isSneaking())
            this.setDead();
        else if (flag2 && player.isSneaking()) {
            this.changeCustomName();
        }
        return super.interact(player);
    }

 

the isRemote being true is just a test to open a GuiScreen to draw the Entity currently rightclicked the same way it happens when you open a horse inventory. I think I have to tell you what I really want to do. In fact, I have so much questions that are related to my goal but can't be asked in the context of this topic.

 

I want to create an EntityMerchant that acts as an EntityVillager. When rightclicking on it, it opens an interface in which the player can trade with the merchant. While the interface is open,

. The EntityMerchant clicked is being drawn on the gui and all the possible trades that the player can do are related to the entityId. When the player quit the interface, the music stops.

 

For this goal, I suppose I have to trade my GuiScreen for a GuiContainer. This would require a server handling. That is all I've thought about for now.

Squirrel ! Squirrel ! Squirrel !

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When #isRemote is true, that means your code is currently on the logical client side, and is NOT when you want to open container-based GUIs.

 

Entity#interact is called on BOTH client and server side during the interaction process - first on the client during the initial mouse-click, then again on the server after the server receives a packet. You should open the GUI when the world is not remote, i.e. on the server side, since the GuiHandler will open both the Container (server side) and the GUI (client side) automatically when invoked on the server.

 

If you were in a situation that didn't have Minecraft automatically sending packets for you, say you wanted to open your Container-based GUI by a key press instead of entity interaction, then you'd have to do as Ernio said and send your own packet from the client requesting the server to open the GUI.

 

The only time you should open a GUI directly on/from the client side is when there is only a GUI component (no Container) and there are not any important conditions to the GUI being opened. If, for a non-Container based GUI, it is important to know for sure the player is e.g. close enough to the entity, then you should send a packet from the server to the client to open the GUI.

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When #isRemote is true, that means your code is currently on the logical client side, and is NOT when you want to open container-based GUIs.

 

Yes, I did know that, I took some time last days reading the Sides concept on readthedocs.

 

*snip*

 

If you were in a situation that didn't have Minecraft automatically sending packets for you, say you wanted to open your Container-based GUI by a key press instead of entity interaction, then you'd have to do as Ernio said and send your own packet from the client requesting the server to open the GUI.

 

Ok, that makes more sense to me now, thank you all. If I have the possibility to open the gui calling EntityPlayer#openGui directly, then I can do it. Otherwise I would need to send a packet from client to server (will be handled to the server then) that will be able to make some checks then opening the gui.

 

The only time you should open a GUI directly on/from the client side is when there is only a GUI component (no Container) and there are not any important conditions to the GUI being opened. If, for a non-Container based GUI, it is important to know for sure the player is e.g. close enough to the entity, then you should send a packet from the server to the client to open the GUI.

 

That means the packet will be handled in the client ? Which method should I call then ? EntityPlayer#openGui to pass through the GuiHandler or another one from Minecraft base code ?

Squirrel ! Squirrel ! Squirrel !

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