MC 1.19.3 Fabric双格高方块交互功能实现求助

1. 修复顶部区域交互问题 #

Minecraft默认方块射线检测仅识别自身坐标Y=0到Y=1范围内的碰撞，要让2格高的顶部区域触发交互，需重写getRaycastShape方法，将射线检测范围设为与碰撞箱一致的2格高：

@Override
public VoxelShape getRaycastShape(BlockState state, BlockView world, BlockPos pos, ShapeContext context) {
    return SHAPE;
}

修改后，玩家点击顶部区域时，射线会命中下方的VendingMachineBlock，进而触发onUse方法。你原有代码中的相对Y位置判断逻辑，此时就能正确响应顶部区域的点击。

2. 阻止上方放置方块覆盖 #

当前canReplace方法仅处理替换现有方块的场景，玩家向空的上方位置放置方块时不会生效。需通过自定义BlockItem拦截放置行为：

步骤1：创建自定义BlockItem #

public class VendingMachineBlockItem extends BlockItem {
    public VendingMachineBlockItem(Block block, Settings settings) {
        super(block, settings);
    }

    @Override
    public ActionResult place(ItemPlacementContext context) {
        BlockPos targetPos = context.getBlockPos();
        // 拦截在自动售货机正上方的放置操作
        if (context.getWorld().getBlockState(targetPos.down()).isOf(getBlock())) {
            return ActionResult.FAIL;
        }
        return super.place(context);
    }
}

步骤2：注册方块时关联自定义BlockItem #

在模组注册类中，注册方块时使用自定义的VendingMachineBlockItem：

public static final Block VENDING_MACHINE = registerBlock("vending_machine",
        new VendingMachineBlock(),
        new Item.Settings().group(ItemGroup.MISC));

// 注册方法示例
private static Block registerBlock(String name, Block block, Item.Settings settings) {
    Block registeredBlock = Registry.register(Registry.BLOCK, new Identifier(MOD_ID, name), block);
    Registry.register(Registry.ITEM, new Identifier(MOD_ID, name), new VendingMachineBlockItem(block, settings));
    return registeredBlock;
}

3. 完整修改后的VendingMachineBlock代码 #

public class VendingMachineBlock extends Block {
    private static final VoxelShape SHAPE = Block.createCuboidShape(0, 0, 0, 16, 32, 16);

    public VendingMachineBlock() {
        super(Settings.of(Material.METAL)
                .nonOpaque()
                .strength(4.0f)
                .requiresTool()
                .sounds(BlockSoundGroup.METAL)
        );
    }

    @Override
    public VoxelShape getOutlineShape(BlockState state, BlockView world, BlockPos pos, ShapeContext context) {
        return SHAPE;
    }

    @Override
    public VoxelShape getCollisionShape(BlockState state, BlockView world, BlockPos pos, ShapeContext context) {
        return SHAPE;
    }

    @Override
    public VoxelShape getRaycastShape(BlockState state, BlockView world, BlockPos pos, ShapeContext context) {
        return SHAPE;
    }

    @Override
    public boolean canReplace(BlockState state, ItemPlacementContext context) {
        BlockPos pos = context.getBlockPos();
        if (context.getWorld().getBlockState(pos.down()).isOf(this)) {
            return false;
        }
        return super.canReplace(state, context);
    }

    @Override
    public ActionResult onUse(BlockState state, World world, BlockPos pos, PlayerEntity player, Hand hand, BlockHitResult hit) {
        double relativeHitY = hit.getPos().y - pos.getY();
        // 覆盖0到2的完整2格范围，处理所有区域的交互
        if (relativeHitY >= 0 && relativeHitY <= 2) {
            if (!world.isClient) {
                player.sendMessage(Text.of("Hello, world!"), false);
                // 后续可在此处添加GUI打开逻辑
                // player.openHandledScreen(state.createScreenHandlerFactory(world, pos));
            }
            return ActionResult.SUCCESS;
        }
        return super.onUse(state, world, pos, player, hand, hit);
    }
}

内容的提问来源于stack exchange，提问作者Captain