initial commit

internal/chunk/chunk.go

@@ -0,0 +1,119 @@
+package chunk
+
+import (
+	"github.com/df-mc/dragonfly/server/block/cube"
+	"sync"
+)
+
+// Chunk is a segment in the world with a size of 16x16x256 blocks. A chunk contains multiple sub chunks
+// and stores other information such as biomes.
+// It is not safe to call methods on Chunk simultaneously from multiple goroutines.
+type Chunk struct {
+	sync.Mutex
+	// r holds the (vertical) range of the Chunk. It includes both the minimum and maximum coordinates.
+	r cube.Range
+	// air is the runtime ID of air.
+	air uint32
+	// sub holds all sub chunks part of the chunk. The pointers held by the array are nil if no sub chunk is
+	// allocated at the indices.
+	sub []*SubChunk
+	// biomes is an array of biome IDs. There is one biome ID for every column in the chunk.
+	biomes []*PalettedStorage
+}
+
+// New initialises a new chunk and returns it, so that it may be used.
+func New(air uint32, r cube.Range) *Chunk {
+	n := (r.Height() >> 4) + 1
+	sub, biomes := make([]*SubChunk, n), make([]*PalettedStorage, n)
+	for i := 0; i < n; i++ {
+		sub[i] = NewSubChunk(air)
+		biomes[i] = emptyStorage(0)
+	}
+	return &Chunk{r: r, air: air, sub: sub, biomes: biomes}
+}
+
+// Range returns the cube.Range of the Chunk as passed to New.
+func (chunk *Chunk) Range() cube.Range {
+	return chunk.r
+}
+
+// Sub returns a list of all sub chunks present in the chunk.
+func (chunk *Chunk) Sub() []*SubChunk {
+	return chunk.sub
+}
+
+// Block returns the runtime ID of the block at a given x, y and z in a chunk at the given layer. If no
+// sub chunk exists at the given y, the block is assumed to be air.
+func (chunk *Chunk) Block(x uint8, y int16, z uint8, layer uint8) uint32 {
+	sub := chunk.subChunk(y)
+	if sub.Empty() || uint8(len(sub.storages)) <= layer {
+		return chunk.air
+	}
+	return sub.storages[layer].At(x, uint8(y), z)
+}
+
+// SetBlock sets the runtime ID of a block at a given x, y and z in a chunk at the given layer. If no
+// SubChunk exists at the given y, a new SubChunk is created and the block is set.
+func (chunk *Chunk) SetBlock(x uint8, y int16, z uint8, layer uint8, block uint32) {
+	sub := chunk.sub[chunk.subIndex(y)]
+	if uint8(len(sub.storages)) <= layer && block == chunk.air {
+		// Air was set at n layer, but there were less than n layers, so there already was air there.
+		// Don't do anything with this, just return.
+		return
+	}
+	sub.Layer(layer).Set(x, uint8(y), z, block)
+}
+
+// BiomeSub returns a list of all biome sub chunks present in the chunk.
+func (chunk *Chunk) BiomeSub() []*PalettedStorage {
+	return chunk.biomes
+}
+
+// Biome returns the biome ID at a specific column in the chunk.
+func (chunk *Chunk) Biome(x uint8, y int16, z uint8) uint32 {
+	return chunk.biomes[chunk.subIndex(y)].At(x, uint8(y), z)
+}
+
+// SetBiome sets the biome ID at a specific column in the chunk.
+func (chunk *Chunk) SetBiome(x uint8, y int16, z uint8, biome uint32) {
+	chunk.biomes[chunk.subIndex(y)].Set(x, uint8(y), z, biome)
+}
+
+// HighestBlock iterates from the highest non-empty sub chunk downwards to find the Y value of the highest
+// non-air block at an x and z. If no blocks are present in the column, 0 is returned.
+func (chunk *Chunk) HighestBlock(x, z uint8) int16 {
+	for index := int16(len(chunk.sub) - 1); index >= 0; index-- {
+		if sub := chunk.sub[index]; !sub.Empty() {
+			for y := 15; y >= 0; y-- {
+				if rid := sub.storages[0].At(x, uint8(y), z); rid != chunk.air {
+					return int16(y) | chunk.subY(index)
+				}
+			}
+		}
+	}
+	return int16(chunk.r[0])
+}
+
+// Compact compacts the chunk as much as possible, getting rid of any sub chunks that are empty, and compacts
+// all storages in the sub chunks to occupy as little space as possible.
+// Compact should be called right before the chunk is saved in order to optimise the storage space.
+func (chunk *Chunk) Compact() {
+	for i := range chunk.sub {
+		chunk.sub[i].compact()
+	}
+}
+
+// subChunk finds the correct SubChunk in the Chunk by a Y value.
+func (chunk *Chunk) subChunk(y int16) *SubChunk {
+	return chunk.sub[chunk.subIndex(y)]
+}
+
+// subIndex returns the sub chunk Y index matching the y value passed.
+func (chunk *Chunk) subIndex(y int16) int16 {
+	return (y - int16(chunk.r[0])) >> 4
+}
+
+// subY returns the sub chunk Y value matching the index passed.
+func (chunk *Chunk) subY(index int16) int16 {
+	return (index << 4) + int16(chunk.r[0])
+}