Accessing Blocks

Grundlæggende oplysninger

Blocks are most commonly identified and accessed by their Location. This location points to a certain coordinate within an Extent. In most cases a World will be used as the Extent.

import org.spongepowered.api.Sponge;
import org.spongepowered.api.world.Location;
import org.spongepowered.api.world.World;

public Location<World> getBlockAt(String worldName, int posX, int posY, int posZ) {
    World world = Sponge.getServer().getWorld(worldName).get();
    Location<World> blockLoc = new Location<World>(world, posX, posY, posZ);
    return blockLoc;
}

Advarsel

Bemærk at eksemplet ovenfor ikke kontrollere, om verden eksisterer. ›‹ getWorld(worldName).get()‹‹ mislykkes, hvis der indlæses ingen verden af samme navn.

With this Location object you can then obtain further information about the block. The following code checks if a referenced block is any kind of banner by checking the blocks type.

import org.spongepowered.api.block.BlockType;
import org.spongepowered.api.block.BlockTypes;

public boolean isBanner(Location<World> blockLoc) {
    BlockType type = blockLoc.getBlock().getType();
    return type.equals(BlockTypes.STANDING_BANNER)
            || type.equals(BlockTypes.WALL_BANNER);
}

Tip

Funktion ›‹ ==‹‹ kunne anvendes i stedet for ›‹ equals()‹‹ der er kun én :javadoc: ›BlockType‹ instans for hver blok, men det er generelt anbefalet at bruge ›‹ equals()‹‹.

Block Data Manipulators

The data of a block is held as a DataManipulator, similar to other parts of the API. This is the container that holds information on components of our block such as the orientation of a block, specific types (stone vs. granite), and so on. Checking the values of these manipulators is easy, you just need to check the block’s direction DirectionalData.

import org.spongepowered.api.data.key.Keys;
import org.spongepowered.api.data.manipulator.mutable.block.DirectionalData;

public boolean isFacingNorth(Location<World> blockLoc) {
    Optional<DirectionalData> optionalData = blockLoc.get(DirectionalData.class);
    if (!optionalData.isPresent()) {
        return false;
    }
    DirectionalData data = optionalData.get();
    if (data.get(Keys.DIRECTION).get().equals(Direction.NORTH)) {
        return true;
    }
    return false;
}

First, we need to know which DataManipulator sub-interface we need. Those that are applicable to blocks are found in the org.spongepowered.api.data.manipulator.mutable and org.spongepowered.api.data.manipulator.mutable.block packages. Then, we can just pass that class to the get(DataManipulator) method of Location which will return an Optional. We then have to check if our DataManipulator actually exists for our block by checking ifPresent(). If it exists, then we can use it.

More on DataManipulators can be found in the data documentation.

Tip

If a block will never stop supporting a particular DataManipulator, such as DirectionalData with stairs, then there is no need to check for isPresent(). Just remove the optional around the DataManipulator and fetch the non-optional data by adding .get() to the end of the statement. Note, that this will cause a NullPointerException if a block ever stops supporting a particular DataManipulator.

Block States

A BlockState contains a BlockType, any DataManipulators and properties that are applied to the block, and any BlockTraits for a block. It stores all immutable value’s for a particular block. One use of this is getting an ImmutableDataManipulator, as shown below:

import org.spongepowered.api.block.BlockState;
import org.spongepowered.api.data.manipulator.immutable.ImmutableWetData;

public void isWet(Location blockLoc) {
    BlockState sponge = blockLoc.getBlock();
    if (!sponge.getType().equals(BlockTypes.SPONGE)) {
        return false;
    }
    Optional<ImmutableWetData> wetness = sponge.get(ImmutableWetData.class);
    return wetness.isPresent();
}

More information on mutable and immutable DataManipulators can be found in the data documentation.

Block Properties

Blocks can contain certain properties. A property is a pre-set value that defines the game logic of that particular block. For example, blocks can contain pre-determined blast-resistance values that can be used to determine what you’re working with, without actually checking the type of block it could be one by one. For example, if we wanted to get the blast resistance of a block and checking if it is greater than or equal to one, it would be done like so:

import org.spongepowered.api.data.property.DoubleProperty;
import org.spongepowered.api.data.property.block.BlastResistanceProperty;

public boolean blastResistanceGreaterThanOne(Location<World> blockLoc) {
    Optional<BlastResistanceProperty> optional =
        blockLoc.getProperty(BlastResistanceProperty.class);

    if(optional.isPresent()) {
        BlastResistanceProperty resistance = optional.get();
        DoubleProperty one = DoubleProperty.greaterThanOrEqual(1);
        return one.matches(resistance);
    }
    return false;
}

This will get the blast resistance of our block and compare it to a new DoubleProperty, as BlastResistanceProperty inherits from DoubleProperty. The method will then return if the blast resistance of our block is greater than one, the value in placed matches(). If we wanted to see if it was less than two, we would replace it with lessThan().

If we were comparing two pre-existing properties, it will take the Operator of our first value, the one we are creating a double property for. If the Operator is DELEGATE, which is the none operator, then it will take the Operator of the second value, the one in matches(). Comparison will return false if both are DELEGATE. An example of comparing two PoweredPropertys, a BooleanProperty, can be seen below:

import org.spongepowered.api.data.property.block.PoweredProperty;

public boolean areBlocksPowered(Location<World> blockLoc, Location<World> blockLoc2) {
    Optional<PoweredProperty> optional = blockLoc.getProperty(PoweredProperty.class);
    Optional<PoweredProperty> optional2 = blockLoc2.getProperty(PoweredProperty.class);

    if(optional.isPresent() && optional2.isPresent()) {
        PoweredProperty property1 = optional2.get();
        PoweredProperty property2 = optional2.get();
        BooleanProperty booleanProperty = BooleanProperty.of(property1);
        BooleanProperty booleanProperty2 = BooleanProperty.of(true);

        if(booleanProperty2.matches(property1)) {
            return booleanProperty.matches(property2);
        }
    }
    return false;
}

The second if check checks if one of the properties is true. If it is true and both are equal, then both of the values must be true. Therefore, eliminating the need to check the second value. Now we know that both blocks are being powered.

A list of possible block properties can be found in the org.spongepowered.api.data.property.block package.

Block Traits

A block trait is a certain value on the current state of a block. A block may or may not contain block traits depending on the type of block. For example, a bed has a BooleanTrait called BED_OCCUPIED. As a boolean can only have two values, true and false, the BED_OCCUPIED trait can only be true or false. Checking this value is simple, just call the BlockState#getTraitValue(BlockTrait) method. An example of this with a bed is shown below:

import org.spongepowered.api.block.trait.BooleanTraits;

public boolean isBedOccupied(Location<World> blockLoc) {
    if(blockLoc.getBlock().getType().equals(BlockTypes.BED)) {
        return blockLoc.getBlock().getTraitValue(BooleanTraits.BED_OCCUPIED).get();
    }
    return false;
}

Advarsel

If possible, it is recommended to use DataManipulators in place of BlockTraits where possible as they are only to be meant as a fallback for modded compatibility.