[1.7.10] Making a tool have special effects on certain blocks

flamedragonX2 · March 21, 2016

So I'm making a mod, and I want a tool that, when mining certain blocks, has the block drop something different (not all blocks, just certain ones). For example, mining block A may drop block A, but mining block B will make it drop item C or block D. Kind of like Twilight Forest's fiery pick, except only for a few specific blocks (not anything with a smelting recipe).

How would I go about doing this? Logically I'd go about doing something to the tool's onBlockDestroyed() method, but I don't know exactly what to do about it. And this is not something that I can easily search up modding tutorials for as it is not something commonly attempted. And, if one of the blocks I want to check for is stone, would this code be appropriate for checking if the block is stone?

if(block.getIdFromBlock(block) == block.getIdFromBlock(Blocks.stone))
{
//drop a different block here
}

And finally, what would be the code for spawning a dropped item? Not sure if I need it here or not, but I think it may help in the future.

flamedragonX2 · March 21, 2016

How do I use a HarvestDropsEvent?

Do I create a separate class to handle this, or can I put it in the code for my mod pickaxe class?

flamedragonX2 · March 21, 2016

Thanks, I was able to use the harvesting event to get a block to drop something additional when a specific tool is used.

I guess I could look this up but since I'm here, how to I get the event to remove a drop?

Draco18s · March 21, 2016

event.drops.clear()

It's an array list, use it like one.

flamedragonX2 · March 21, 2016

Thanks, this will really help.

flamedragonX2 · March 21, 2016

Darn it, I've run into another problem.

So I created a pickaxe that when mining stone drops my custom block, and has a 25% chance to set the player on fire when mining a block. Code for harvest event below:

(Note: some of it is obfuscated with xxxx to keep names a secret)

@SubscribeEvent
public void xxxxPick(HarvestDropsEvent event)
{
	ItemStack theTool = event.harvester.getCurrentEquippedItem();
	if(theTool != null)
	{
		if(theTool.getItem() == ToolManager.xxxxPickaxe)
		{	
			if(random.nextInt(4) == 0)
			{
				event.harvester.setFire(5);
			}

			if(event.block != null)
			{
				if(event.block == Blocks.stone)
				{
					event.drops.clear();
					event.drops.add(new ItemStack(Item.getItemFromBlock(myBlocksClass.myCustomStone)));
				}
			}				
		}
	}

However, occasionally I get a crash report, stating a NullPointerException has occured doing my custom pick event. This really confuses me since I checked to see if both the block and the tool are not null before using them. Example below:

// Hi. I'm Minecraft, and I'm a crashaholic.

Time: 3/21/16 7:12 PM

Description: Exception ticking world

java.lang.NullPointerException: Exception ticking world

at net.xxxxxx.events.HarvestingEvents.xxxxPick(HarvestingEvents.java:38)

at cpw.mods.fml.common.eventhandler.ASMEventHandler_6_HarvestingEvents_xxxxPick_HarvestDropsEvent.invoke(.dynamic)

at cpw.mods.fml.common.eventhandler.ASMEventHandler.invoke(ASMEventHandler.java:54)

at cpw.mods.fml.common.eventhandler.EventBus.post(EventBus.java:140)

at net.minecraftforge.event.ForgeEventFactory.fireBlockHarvesting(ForgeEventFactory.java:162)

at net.minecraft.block.Block.dropBlockAsItemWithChance(Block.java:806)

at net.minecraft.block.Block.dropBlockAsItem(Block.java:795)

at net.minecraft.block.BlockBush.checkAndDropBlock(BlockBush.java:74)

at net.minecraft.block.BlockBush.updateTick(BlockBush.java:64)

at net.minecraft.world.WorldServer.func_147456_g(WorldServer.java:408)

at net.minecraft.world.WorldServer.tick(WorldServer.java:191)

at net.minecraft.server.MinecraftServer.updateTimeLightAndEntities(MinecraftServer.java:692)

at net.minecraft.server.MinecraftServer.tick(MinecraftServer.java:614)

at net.minecraft.server.integrated.IntegratedServer.tick(IntegratedServer.java:118)

at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:485)

at net.minecraft.server.MinecraftServer$2.run(MinecraftServer.java:752)

A detailed walkthrough of the error, its code path and all known details is as follows:

---------------------------------------------------------------------------------------

-- Head --

Stacktrace:

at net.xxxxxxx.events.HarvestingEvents.xxxxPick(HarvestingEvents.java:38)