Which is better: Changing my tile entity data on both the server and client but never sync it, or changing it only on the server and sync it to the client? And if the answer is the second one, how would I do it?

That depends:

Does the client ever need to know this information?

Yes.

Then sync the data.

Ok, how would I go about that? I played around a bit with tile entities in 1.7.10 but the syncing system has changed so I'm completely lost.

Override getUpdatePacket and getUpdateTag()

 

getUpdatePacket will return a new package with the contents returned from getUpdateTag, where you write all the TE's information in it.  You can get away with just using the same nbt that's saved to disk, as long as there isn't a ton of data the client doesn't need.

I tried that but it doesn't work. Heres my code:

public class TileCrystalFurnace extends TileEntity implements ITickable {

private static ArrayList<Block> hotBlocks = new ArrayList();

static {
	hotBlocks.add(Blocks.LAVA);
	hotBlocks.add(Blocks.FLOWING_LAVA);
	hotBlocks.add(Block.getBlockFromName("magma"));
}

private ItemStackHandler inventory = new ItemStackHandler(2) {
	@Override
	protected void onContentsChanged(int slot) {
		TileCrystalFurnace.this.markDirty();
	}

	@Override
	protected int getStackLimit(int slot, ItemStack stack) {
		if (slot == 0) {
			if (stack.getItem() == Items.DIAMOND) return super.getStackLimit(slot, stack);
		} else if (slot == 1) {
			if (stack.getItem() == Item.getItemFromBlock(Blocks.GLASS)) return super.getStackLimit(slot, stack);
		}
		return 0;
	}

};

private FluidTank crystalTank = new FluidTank(Fluid.BUCKET_VOLUME * 2) {
	@Override
	protected void onContentsChanged() {
		TileCrystalFurnace.this.markDirty();
	}
};

public boolean isHeated;
public boolean isMelting;
public int meltTime = 0;

public TileCrystalFurnace() {
	crystalTank.setCanFill(false);
}

@Override
public void update() {
	isHeated = worldObj.getBlockState(pos.add(0, -1, 0)) != null && hotBlocks.contains(worldObj.getBlockState(pos.add(0, -1, 0)).getBlock());

	if (worldObj.isRemote) return;

	if (isHeated && !isMelting && inventory.extractItem(0, 1, true) != null && inventory.extractItem(1, 3, true) != null && inventory.extractItem(1, 3, true).stackSize == 3 && crystalTank.fillInternal(new FluidStack(EnchantedAura.liquidCrystal, 500), false) == 500) {
		inventory.extractItem(0, 1, false);
		inventory.extractItem(1, 3, false);
		isMelting = true;
		meltTime = 400;
		this.markDirty();
	}

	if (isMelting && meltTime == 0) {
		isMelting = false;
		crystalTank.fillInternal(new FluidStack(EnchantedAura.liquidCrystal, 500), true);
		this.markDirty();
	}

	if (isMelting && isHeated) {
		meltTime--;
		this.markDirty();
	}

}

@Override
public void readFromNBT(NBTTagCompound compound) {
	super.readFromNBT(compound);

	inventory.deserializeNBT(compound.getCompoundTag("inventory"));
	crystalTank.readFromNBT(compound.getCompoundTag("crystalTank"));

	meltTime = compound.getInteger("meltTime");
	isMelting = compound.getBoolean("isMelting");
}

@Override
public NBTTagCompound writeToNBT(NBTTagCompound compound) {
	compound.setTag("inventory", inventory.serializeNBT());
	compound.setTag("crystalTank", crystalTank.writeToNBT(new NBTTagCompound()));

	compound.setInteger("meltTime", meltTime);
	compound.setBoolean("isMelting", isMelting);

	return super.writeToNBT(compound);
}

@Override
public boolean hasCapability(Capability<?> capability, EnumFacing facing) {
	if (capability == CapabilityItemHandler.ITEM_HANDLER_CAPABILITY || capability == CapabilityFluidHandler.FLUID_HANDLER_CAPABILITY)
		return true;
	return super.hasCapability(capability, facing);
}

@Override
public <T> T getCapability(Capability<T> capability, EnumFacing facing) {
	if (capability == CapabilityItemHandler.ITEM_HANDLER_CAPABILITY)
		return (T) inventory;
	else if (capability == CapabilityFluidHandler.FLUID_HANDLER_CAPABILITY)
		return (T) crystalTank;
	return super.getCapability(capability, facing);
}

@Override
public final NBTTagCompound getUpdateTag() {
	return this.writeToNBT(new NBTTagCompound());
}

@Override
public SPacketUpdateTileEntity getUpdatePacket() {
	return new SPacketUpdateTileEntity(this.getPos(), 1, this.getUpdateTag());
}

}

 

My GUI never shows the progress bar moving, or liquid entering the tank. It does show the items disappearing however thats probably because the container syncs items.

1) Mark dirty says "this needs to be saved to disk" not "send this to the client."

2) I believe the method you want is now called

worldObj.markAndNotifyBlock(pos, chunk, iblockstate, newState, flags);

3) The client isn't updating its own values on its end because you did

if (worldObj.isRemote) return;

(you can safely remove that for the most part)

2) I believe the method you want is now called worldObj.markAndNotifyBlock(pos, chunk, iblockstate, newState, flags);

 

If the only reason for marking an update is to sync tile entity data to the client for rendering purposes, then worldObj.notifyBlockUpdate(pos, oldState, newState, flags) looks to be a better option.  markAndNotifyBlock() works - it calls notifyBlockUpdate() - but it also notifies the block's neighbours of a blockstate change, and may cause some comparator recalculation - extra unnecessary server load if you're just syncing TE data.

 

Thanks desht.

 

I have trouble finding that method because the 1.7 name was "markBlockForUpdate" or similar, so I type "mark..." and autocompletion gives me results that don't include that one.