Walking on water

[yanksrock1019]

So a youtuber named Syndicate said that he really wanted an enchantment that would let you walk on water.  How would I go about doing that? Would I have the effect use the property of a boat floating in order to float on water?

[Mitchellbrine]

I'd make the player's motionY 0.0 when the block below him is water.

[yanksrock1019]

Would I put that in my tick handler class

[coolAlias]

Why not put it in whatever Item class that has the enchantment? Or would the enchantment be on many different kinds of items?

 

In the latter case, I'd put it in the PlayerTickEvent.

 

I've done something similar in the past, and I found that subtracting the previous motionY before equalizing it gave the best results, something like:

flag = is block directly under player a water block?
if (flag && player.motionY < 0.0D) {
player.posY += -player.motionY; // player is falling, so motionY is negative, but we want to reverse that
player.motionY = 0.0D; // no longer falling
player.fallDistance = 0.0F; // otherwise I believe it adds up, which may surprise you when you come down
}

[yanksrock1019]

Not sure what to do with the flag

[Mitchellbrine]

World.getBlock much?

[yanksrock1019]

Nope doesn't work

[coolAlias]

Nope doesn't work

<sigh> Your last few comments sorely contest the bold statement in your signature...

 

int i = MathHelper.floor_double(player.posX);
int j = MathHelper.floor_double(player.boundingBox.minY);
int k = MathHelper.floor_double(player.posZ);
Material m = world.getBlock(i, j, k).getMaterial();
boolean flag = (m == Material.water); // or m.isLiquid() or whatever you want.

[yanksrock1019]

"Cannot make a static reference to the non-static method getBlock(int, int, int) from the type World"

 

Sorry this may be noob questions

 

The signature was just so that people started helping me rather than saying "Learn Basic Java" in situations that had nothing to do with basic java

[yanksrock1019]

BTW, the first thing is the error I get on World.getBlock(i, j, k).getMaterial();

[Tikaji]

couldnt you check to see if the block below is an instance of BlockLiquid and then make your y movement 0?

[coolAlias]

"Cannot make a static reference to the non-static method getBlock(int, int, int) from the type World"

 

Sorry this may be noob questions

 

The signature was just so that people started helping me rather than saying "Learn Basic Java" in situations that had nothing to do with basic java

Sure, but that is exactly the kind of thing people mean when they say 'Learn Basic Java' - that error message is basic Java, as in you cannot do "World.method()" because the method is not a static method, so you need an instance of World to access it.

 

A little time on Google or Oracle's Java tutorials page goes a long way.

[yanksrock1019]

So that would be like "public static getBlock(int i, int j, int k)"

[coolAlias]

So that would be like "public static getBlock(int i, int j, int k)"

Just Google 'cannot make a static reference' and you'll learn all about it. And no, you are NOT going to be re-writing the class methods of World. You need an instance of World - Google 'instance of class' or 'class object' or go through any basic Java tutorial and you'll learn what that is. Please.

[yanksrock1019]

So I did some research and I tried "World world = new World();" but I get "Cannot instantiate the type World" and I can't find an answer for this

[coolAlias]

So I did some research and I tried "World world = new World();" but I get "Cannot instantiate the type World" and I can't find an answer for this

Even if you could instantiate it, it would be wrong to do so - how did you plan on initializing that object to contain all the correct information? Anyway, at least you did some research.

 

Whenever you are in need of something, chances are you can find it in the parameters passed to whatever method you are in (you are writing this code inside of some class method somewhere, right? like onItemUpdate or something, right???).

[yanksrock1019]

Yes, it's under onPlayerTick

[coolAlias]

Yes, it's under onPlayerTick

So what's the problem? Every entity has a world object, and the player is an entity.

[jabelar]

For finding the block under an entity, you need to be bit careful with the y value as entities have a yOffset.  if you follow the code in the build-in method onEntityWalking() I think you need code like this:

 

public Block findBlockUnderEntity()
{
    return worldObj.getBlock(MathHelper.floor_double(posX), 
          MathHelper.floor_double(posY - 0.20000000298023224D - (double)yOffset), 
          MathHelper.floor_double(posZ));
}

[coolAlias]

For finding the block under an entity, you need to be bit careful with the y value as entities have a yOffset.  if you follow the code in the build-in method onEntityWalking() I think you need code like this:

 

public Block findBlockUnderEntity()
{
    return worldObj.getBlock(MathHelper.floor_double(posX), 
          MathHelper.floor_double(posY - 0.20000000298023224D - (double)yOffset), 
          MathHelper.floor_double(posZ));
}

Or you could use what I mentioned earlier, though I forgot to mention you need to subtract 1 to get the block underneath:

int j = MathHelper.floor_double(player.boundingBox.minY);

That way you don't have to worry about any offset, as it's already at your feet regardless of the entity's size.

[jabelar]

Yeah, boundingbox is good idea, but I was worried about your lack of -1 ...  I know I've been immensely frustrated before trying to debug why code wasn't returning the block until I realized the -1 was missing... so I got in the habit of just copying the vanilla onEntityWalking().  But now that you mention it, for custom entities the yOffset is likely not very trustworthy while boundingbox is.  Good idea.

 

(Note this thread is becoming one of those where we all have fun showing off our expertise, but I'm not sure the person who started the thread is really making progress...) 

 

 

[yanksrock1019]

So what's the problem? Every entity has a world object, and the player is an entity.

 

I don't know why I'm getting that error, here is the entire code

 

public static void onPlayerTick(EntityPlayer player){

	if(player.getCurrentArmor(0)!= null){



		ItemStack boots = player.getCurrentArmor(0);	

		if(boots.getItem() == Items.diamond_boots || boots.getItem() == Items.golden_boots || boots.getItem() == Items.iron_boots || boots.getItem() == Items.leather_boots || boots.getItem() == Items.chainmail_boots || boots.getItem() == PupletItems.bootsPuplet){

			World world = new World();
			int i = MathHelper.floor_double(player.posX);
			int j = MathHelper.floor_double(player.boundingBox.minY - 1);
			int k = MathHelper.floor_double(player.posZ);
			Material m = world.getBlock(i, j, k).getMaterial();
			boolean flag = (m == Material.water);

			int l = EnchantmentHelper.getEnchantmentLevel(MainClass.waterWalking.effectId, boots);

				if(l > 0 && flag && player.motionY < 0.0D){
					player.posY += -player.motionY; 
					player.motionY = 0.0D; 
					player.fallDistance = 0.0F; 
			}
		}
	}
}

[target.san]

<sigh>

replace

World world = new World();

with

World world = player.worldObj;

 

Every entity instance has a field with reference to world it belongs to. And yes, go learn some basic Java. Learn to analyze Forge sources you already have at your hand.

[coolAlias]

public static void onPlayerTick(EntityPlayer player)

That's not how events work.

 

Here is a tutorial on how to use events.

[yanksrock1019]

That's not how events work.

Yeah, just reliazed.  However, now whenever I walk on water with the boots minecraft gives me an error that says "Illegal stance."