minecraft - section.go

     1  package minecraft
     2  
     3  import (
     4  	"vimagination.zapto.org/minecraft/nbt"
     5  )
     6  
     7  func yzx(x, y, z int32) uint32 {
     8  	return (uint32(y&15) << 8) | (uint32(z&15) << 4) | uint32(x&15)
     9  }
    10  
    11  func getNibble(arr nbt.ByteArray, x, y, z int32) byte {
    12  	coord := yzx(x, y, z)
    13  	data := byte(arr[coord>>1])
    14  	if coord&1 == 0 {
    15  		return data & 15
    16  	}
    17  	return data >> 4
    18  }
    19  
    20  func setNibble(arr nbt.ByteArray, x, y, z int32, data byte) {
    21  	coord := yzx(x, y, z)
    22  	oldData := byte(arr[coord>>1])
    23  	if coord&1 == 0 {
    24  		oldData = oldData&240 | data&15
    25  	} else {
    26  		oldData = oldData&15 | data<<4
    27  	}
    28  	arr[coord>>1] = int8(oldData)
    29  }
    30  
    31  type section struct {
    32  	section    nbt.Compound
    33  	blocks     nbt.ByteArray
    34  	add        nbt.ByteArray
    35  	data       nbt.ByteArray
    36  	blockLight nbt.ByteArray
    37  	skyLight   nbt.ByteArray
    38  }
    39  
    40  func newSection(y int32) *section {
    41  	s := new(section)
    42  	s.blocks = make(nbt.ByteArray, 4096)
    43  	s.add = make(nbt.ByteArray, 2048)
    44  	s.data = make(nbt.ByteArray, 2048)
    45  	s.blockLight = make(nbt.ByteArray, 2048)
    46  	s.skyLight = make(nbt.ByteArray, 2048)
    47  	for i := 0; i < 2048; i++ {
    48  		s.skyLight[i] = -1
    49  	}
    50  	s.section = nbt.Compound{
    51  		nbt.NewTag("Blocks", s.blocks),
    52  		nbt.NewTag("Add", s.add),
    53  		nbt.NewTag("Data", s.data),
    54  		nbt.NewTag("BlockLight", s.blockLight),
    55  		nbt.NewTag("SkyLight", s.skyLight),
    56  		nbt.NewTag("Y", nbt.Byte(y>>4)),
    57  	}
    58  	return s
    59  }
    60  
    61  func loadSection(c nbt.Compound) (*section, error) {
    62  	s := new(section)
    63  	s.section = c
    64  	blocks := c.Get("Blocks")
    65  	if blocks.TagID() == 0 {
    66  		return nil, MissingTagError{"[SECTION]->Blocks"}
    67  	} else if blocks.TagID() != nbt.TagByteArray {
    68  		return nil, WrongTypeError{"Blocks", nbt.TagByteArray, blocks.TagID()}
    69  	}
    70  	s.blocks = blocks.Data().(nbt.ByteArray)
    71  	if len(s.blocks) != 4096 {
    72  		return nil, ErrOOB
    73  	}
    74  	add := c.Get("Add")
    75  	if add.TagID() != 0 {
    76  		if add.TagID() != nbt.TagByteArray {
    77  			return nil, WrongTypeError{"Add", nbt.TagByteArray, add.TagID()}
    78  		}
    79  		s.add = add.Data().(nbt.ByteArray)
    80  	} else {
    81  		s.add = make(nbt.ByteArray, 2048)
    82  		c.Set(nbt.NewTag("Add", s.add))
    83  	}
    84  	if len(s.add) != 2048 {
    85  		return nil, ErrOOB
    86  	}
    87  	data := c.Get("Data")
    88  	if data.TagID() == 0 {
    89  		return nil, MissingTagError{"[SECTION]->Data"}
    90  	} else if data.TagID() != nbt.TagByteArray {
    91  		return nil, WrongTypeError{"Data", nbt.TagByteArray, data.TagID()}
    92  	}
    93  	s.data = data.Data().(nbt.ByteArray)
    94  	if len(s.data) != 2048 {
    95  		return nil, ErrOOB
    96  	}
    97  	blockLight := c.Get("BlockLight")
    98  	if blockLight.TagID() == 0 {
    99  		return nil, MissingTagError{"[SECTION]->BlockLight"}
   100  	} else if blockLight.TagID() != nbt.TagByteArray {
   101  		return nil, WrongTypeError{"BlockLight", nbt.TagByteArray, blockLight.TagID()}
   102  	}
   103  	s.blockLight = blockLight.Data().(nbt.ByteArray)
   104  	if len(s.blockLight) != 2048 {
   105  		return nil, ErrOOB
   106  	}
   107  	skyLight := c.Get("SkyLight")
   108  	if skyLight.TagID() == 0 {
   109  		return nil, MissingTagError{"[SECTION]->SkyLight"}
   110  	} else if skyLight.TagID() != nbt.TagByteArray {
   111  		return nil, WrongTypeError{"SkyLight", nbt.TagByteArray, skyLight.TagID()}
   112  	}
   113  	s.skyLight = skyLight.Data().(nbt.ByteArray)
   114  	if len(s.skyLight) != 2048 {
   115  		return nil, ErrOOB
   116  	}
   117  	y := c.Get("Y")
   118  	if y.TagID() == 0 {
   119  		return nil, MissingTagError{"[SECTION]->Y"}
   120  	} else if y.TagID() != nbt.TagByte {
   121  		return nil, WrongTypeError{"Y", nbt.TagByte, y.TagID()}
   122  	}
   123  	return s, nil
   124  }
   125  
   126  func (s *section) GetBlock(x, y, z int32) Block {
   127  	return Block{
   128  		ID:   uint16(getNibble(s.add, x, y, z))<<8 | uint16(byte(s.blocks[yzx(x, y, z)])),
   129  		Data: getNibble(s.data, x, y, z),
   130  	}
   131  }
   132  
   133  func (s *section) SetBlock(x, y, z int32, b Block) {
   134  	s.blocks[yzx(x, y, z)] = int8(b.ID & 255)
   135  	setNibble(s.add, x, y, z, byte(b.ID>>8))
   136  	setNibble(s.data, x, y, z, b.Data)
   137  }
   138  
   139  func (s *section) GetOpacity(x, y, z int32) uint8 {
   140  	return s.GetBlock(x, y, z).Opacity()
   141  }
   142  
   143  func (s *section) GetBlockLight(x, y, z int32) uint8 {
   144  	return getNibble(s.blockLight, x, y, z)
   145  }
   146  
   147  func (s *section) SetBlockLight(x, y, z int32, l uint8) {
   148  	setNibble(s.blockLight, x, y, z, l)
   149  }
   150  
   151  func (s *section) GetSkyLight(x, y, z int32) uint8 {
   152  	return getNibble(s.skyLight, x, y, z)
   153  }
   154  
   155  func (s *section) SetSkyLight(x, y, z int32, l uint8) {
   156  	setNibble(s.skyLight, x, y, z, l)
   157  }
   158  
   159  func (s *section) SetY(y int32) {
   160  	s.section.Set(nbt.NewTag("Y", nbt.Byte(y>>4)))
   161  }
   162