方块朝向 1.21 Fabric

本篇教程的视频

本篇教程的源代码

Github地址：TutorialMod-Facing-1.21

介绍

这里我们将用两篇教程来讲解方块状态，这一篇讲解方块朝向，下一篇讲解可连接方块的方块状态

简单介绍一下，方块状态是方块独有的一种属性，它可以用来表示方块的不同状态，方块状态的种类相当多，有穷举变种型（variants，名字是我自己定义的），比如以下的acacia_button

{
  "variants": {
    "face=ceiling,facing=east,powered=false": {
      "model": "minecraft:block/acacia_button",
      "x": 180,
      "y": 270
    },
    "face=ceiling,facing=east,powered=true": {
      "model": "minecraft:block/acacia_button_pressed",
      "x": 180,
      "y": 270
    },
    "face=ceiling,facing=north,powered=false": {
      "model": "minecraft:block/acacia_button",
      "x": 180,
      "y": 180
    },
    "face=ceiling,facing=north,powered=true": {
      "model": "minecraft:block/acacia_button_pressed",
      "x": 180,
      "y": 180
    },
    "face=ceiling,facing=south,powered=false": {
      "model": "minecraft:block/acacia_button",
      "x": 180
    },
    "face=ceiling,facing=south,powered=true": {
      "model": "minecraft:block/acacia_button_pressed",
      "x": 180
    },
    "face=ceiling,facing=west,powered=false": {
      "model": "minecraft:block/acacia_button",
      "x": 180,
      "y": 90
    },
    "face=ceiling,facing=west,powered=true": {
      "model": "minecraft:block/acacia_button_pressed",
      "x": 180,
      "y": 90
    },
    "face=floor,facing=east,powered=false": {
      "model": "minecraft:block/acacia_button",
      "y": 90
    },
    "face=floor,facing=east,powered=true": {
      "model": "minecraft:block/acacia_button_pressed",
      "y": 90
    },
    "face=floor,facing=north,powered=false": {
      "model": "minecraft:block/acacia_button"
    },
    "face=floor,facing=north,powered=true": {
      "model": "minecraft:block/acacia_button_pressed"
    },
    "face=floor,facing=south,powered=false": {
      "model": "minecraft:block/acacia_button",
      "y": 180
    },
    "face=floor,facing=south,powered=true": {
      "model": "minecraft:block/acacia_button_pressed",
      "y": 180
    },
    "face=floor,facing=west,powered=false": {
      "model": "minecraft:block/acacia_button",
      "y": 270
    },
    "face=floor,facing=west,powered=true": {
      "model": "minecraft:block/acacia_button_pressed",
      "y": 270
    },
    "face=wall,facing=east,powered=false": {
      "model": "minecraft:block/acacia_button",
      "uvlock": true,
      "x": 90,
      "y": 90
    },
    "face=wall,facing=east,powered=true": {
      "model": "minecraft:block/acacia_button_pressed",
      "uvlock": true,
      "x": 90,
      "y": 90
    },
    "face=wall,facing=north,powered=false": {
      "model": "minecraft:block/acacia_button",
      "uvlock": true,
      "x": 90
    },
    "face=wall,facing=north,powered=true": {
      "model": "minecraft:block/acacia_button_pressed",
      "uvlock": true,
      "x": 90
    },
    "face=wall,facing=south,powered=false": {
      "model": "minecraft:block/acacia_button",
      "uvlock": true,
      "x": 90,
      "y": 180
    },
    "face=wall,facing=south,powered=true": {
      "model": "minecraft:block/acacia_button_pressed",
      "uvlock": true,
      "x": 90,
      "y": 180
    },
    "face=wall,facing=west,powered=false": {
      "model": "minecraft:block/acacia_button",
      "uvlock": true,
      "x": 90,
      "y": 270
    },
    "face=wall,facing=west,powered=true": {
      "model": "minecraft:block/acacia_button_pressed",
      "uvlock": true,
      "x": 90,
      "y": 270
    }
  }
}

这里的face、facing、powered都是方块的属性

显然易见，variants类型的方块状态是根据方块的属性来穷举出所有状态的方块模型，当然它的缺点也很明显，就是当属性过多时，会导致方块状态文件过于庞大，不利于维护

另外，也有组合型（multipart），比如acacia_fence

{
  "multipart": [
    {
      "apply": {
        "model": "minecraft:block/acacia_fence_post"
      }
    },
    {
      "apply": {
        "model": "minecraft:block/acacia_fence_side",
        "uvlock": true
      },
      "when": {
        "north": "true"
      }
    },
    {
      "apply": {
        "model": "minecraft:block/acacia_fence_side",
        "uvlock": true,
        "y": 90
      },
      "when": {
        "east": "true"
      }
    },
    {
      "apply": {
        "model": "minecraft:block/acacia_fence_side",
        "uvlock": true,
        "y": 180
      },
      "when": {
        "south": "true"
      }
    },
    {
      "apply": {
        "model": "minecraft:block/acacia_fence_side",
        "uvlock": true,
        "y": 270
      },
      "when": {
        "west": "true"
      }
    }
  ]
}

这里的multipart类型的方块状态是根据方块的属性来选择应用哪个方块模型，比如这里的栅栏，根据四个面是否可连接来决定应用哪个方块模型（如果说要用穷举法，那得写多长的文件啊）

不过，其实很多方块的方块状态还是用variants类型的，而里面的属性也是相当多的，这里我们就不展开讲解了，有兴趣的可以去看看原版的方块状态文件

我们这里要讲解的参数是facing，上面的acacia_button的其中一个属性就是facing，它表示按钮的朝向，不同的朝向对应不同的模型

原版的门、楼梯等都有facing属性，我们可以去看看它们的源代码，看看它们的这个属性是怎么定义，如何使用的

查看源代码

这里我们以楼梯为例，看看它的facing属性是怎么定义的

StairsBlock类

public static final DirectionProperty FACING = HorizontalFacingBlock.FACING;

在StairsBlock这个类中，我们可以看到它定义了一个DirectionProperty类型的属性FACING，这个属性是HorizontalFacingBlock.FACING，我们再看看HorizontalFacingBlock这个类

HorizontalFacingBlock类

public abstract class HorizontalFacingBlock extends Block {
	public static final DirectionProperty FACING = Properties.HORIZONTAL_FACING;

	protected HorizontalFacingBlock(AbstractBlock.Settings settings) {
		super(settings);
	}

	@Override
	protected abstract MapCodec<? extends HorizontalFacingBlock> getCodec();

	@Override
	protected BlockState rotate(BlockState state, BlockRotation rotation) {
		return state.with(FACING, rotation.rotate(state.get(FACING)));
	}

	@Override
	protected BlockState mirror(BlockState state, BlockMirror mirror) {
		return state.rotate(mirror.getRotation(state.get(FACING)));
	}
}

在HorizontalFacingBlock这个类中，我们可以看到它定义了一个DirectionProperty类型的属性FACING，这个属性是原版定义好的，我们可以直接使用

Properties类

public static final DirectionProperty HORIZONTAL_FACING = DirectionProperty.of("facing", Direction.Type.HORIZONTAL);

我们还可以在追溯至Properties这个类，我们可以看到它定义了一个DirectionProperty.of("facing", Direction.Type.HORIZONTAL)

这个字段注册的id就是facing，也就是对应我们方块状态文件中的facing属性

而在Properties类中还有很多其他的属性，你可以根据需要去查看

实现方块朝向

这里我们就开始来实现方块朝向，我们以前一篇教程的SimpleBlock为例，我们来实现一个朝向的方块

方块类

public class SimpleBlock extends Block {
    
    public SimpleBlock(Settings settings) {
        super(settings);
    }

}

我们先不管其中的碰撞箱，我们先来实现方块朝向

引入FACING属性

public static final DirectionProperty FACING = Properties.HORIZONTAL_FACING;

我们在SimpleBlock这个类中定义一个DirectionProperty类型的属性FACING，直接引用原版的Properties.HORIZONTAL_FACING即可

当然，我们可以让我们的方块类继承HorizontalFacingBlock，这样就不用自己定义FACING属性了，同时也不用再重写那些方法了，但是得写个编解码器

重写rotate、mirror、getPlacementState方法

@Override
protected BlockState rotate(BlockState state, BlockRotation rotation) {
    return state.with(FACING, rotation.rotate(state.get(FACING)));
}

@Override
protected BlockState mirror(BlockState state, BlockMirror mirror) {
    return state.rotate(mirror.getRotation(state.get(FACING)));
}

@Nullable
@Override
public BlockState getPlacementState(ItemPlacementContext ctx) {
    return this.getDefaultState().with(FACING, ctx.getHorizontalPlayerFacing().getOpposite());
}

这里我们重写了rotate、mirror、getPlacementState方法，这三个方法是用来处理方块朝向的

这里的写法和原版的HorizontalFacingBlock类中的不太一样，我们多写了getPlacementState方法，你可以自己来测试一下有什么不同

重写appendProperties方法

@Override
protected void appendProperties(StateManager.Builder<Block, BlockState> builder) {
    builder.add(FACING);
}

以后写方块状态的属性时候记得写这个，这是非常重要的点！！！

不然后面会报错、崩溃

这里我们添加了FACING属性，后面我们在游戏中按F3查看方块状态时就会看到facing属性了

碰撞箱

接下来我们结合方块的朝向，利用BlockBench来生成碰撞箱

public static final VoxelShape SHAPE_N = Stream.of(
    Block.createCuboidShape(0, 0, 0, 16, 2, 16),
    Block.createCuboidShape(0, 14, 0, 16, 16, 16),
    Block.createCuboidShape(0, 2, 2, 16, 14, 16)
).reduce((v1, v2) -> VoxelShapes.combineAndSimplify(v1, v2, BooleanBiFunction.OR)).get();

public static final VoxelShape SHAPE_W = Stream.of(
    Block.createCuboidShape(0, 0, 0, 16, 2, 16),
    Block.createCuboidShape(0, 14, 0, 16, 16, 16),
    Block.createCuboidShape(2, 2, 0, 16, 14, 16)
).reduce((v1, v2) -> VoxelShapes.combineAndSimplify(v1, v2, BooleanBiFunction.OR)).get();

public static final VoxelShape SHAPE_S = Stream.of(
    Block.createCuboidShape(0, 0, 0, 16, 2, 16),
    Block.createCuboidShape(0, 14, 0, 16, 16, 16),
    Block.createCuboidShape(0, 2, 0, 16, 14, 14)
).reduce((v1, v2) -> VoxelShapes.combineAndSimplify(v1, v2, BooleanBiFunction.OR)).get();

public static final VoxelShape SHAPE_E = Stream.of(
    Block.createCuboidShape(0, 0, 0, 16, 2, 16),
    Block.createCuboidShape(0, 14, 0, 16, 16, 16),
    Block.createCuboidShape(0, 2, 0, 14, 14, 16)
).reduce((v1, v2) -> VoxelShapes.combineAndSimplify(v1, v2, BooleanBiFunction.OR)).get();


@Override
protected VoxelShape getOutlineShape(BlockState state, BlockView world, BlockPos pos, ShapeContext context) {
    return switch (state.get(FACING)) {
        case WEST -> SHAPE_W;
        case SOUTH -> SHAPE_S;
        case EAST -> SHAPE_E;
        default -> SHAPE_N;
    };
}

东西南北，一共四个方向，我们分别定义了四个碰撞箱，然后根据方块的朝向来返回对应的碰撞箱

在使用BlockBench生成碰撞箱时，前面说过，我们要将所有的体块放在一个叫VoxelShapes的组下才能导出，名字不能错，大小写也是

然后不同方向的碰撞箱，可以先选中所有体块，然后将枢轴点设置到xz平面的中心，高度轴y可以任意，然后我们选中所有体块，一次旋转90度（建议逆时针，这样就是按照上面的顺序来的），再导出

最后就可以得到我们上面那一堆了

修改构造函数

public SimpleBlock(Settings settings) {
    super(settings);
    this.setDefaultState(this.getStateManager().getDefaultState().with(FACING, Direction.NORTH));
}

这里我们在构造函数中设置了默认的方块朝向为NORTH

注册方块

前面我们已经注册过了，这里就不再赘述了（当然如果你自己又写了一个的话，记得注册，还有物品栏）

数据文件

语言文件我们就不写了，和前面一样的

模型文件

我们方块的模型文件还是之前的，但是方块状态文件得改

blockStateModelGenerator.registerNorthDefaultHorizontalRotation(ModBlocks.SIMPLE_BLOCK);

这里我们用registerNorthDefaultHorizontalRotation方法注册我们的方块，默认面向是NORTH，这样和我们在方块构造函数中设置的默认朝向一致，并且这里会生成带有facing属性的方块状态文件

而后，我们就可以在游戏中测试我们的方块了