94 lines
2.3 KiB
Go
94 lines
2.3 KiB
Go
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package world
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import (
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"encoding/binary"
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"fmt"
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"sort"
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"github.com/segmentio/fasthash/fnv1a"
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)
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// networkBlockHash produces the canonical "network block hash" for a (name, properties) block state.
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// This hash is used for mapping network palette entries back to runtime IDs.
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//
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// The scratch slice is used to reduce allocations. The returned slice should be passed back in on subsequent calls to
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// reuse the same backing array.
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func networkBlockHash(name string, properties map[string]any, scratch []byte) (uint32, []byte) {
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if name == "minecraft:unknown" {
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return 0xfffffffe, scratch // -2
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}
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keys := make([]string, 0, len(properties))
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for k := range properties {
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keys = append(keys, k)
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}
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sort.Strings(keys)
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data := scratch[:0]
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writeString := func(str string) {
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data = binary.LittleEndian.AppendUint16(data, uint16(len(str)))
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data = append(data, []byte(str)...)
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}
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data = append(data, 10) // compound
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data = append(data, 0)
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data = append(data, 0)
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data = append(data, 8) // string
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writeString("name")
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writeString(name)
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data = append(data, 10) // compound
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writeString("states")
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for _, k := range keys {
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v := properties[k]
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switch v := v.(type) {
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case string:
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data = append(data, 8) // string
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writeString(k)
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writeString(v)
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case uint8:
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data = append(data, 1) // tagByte
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writeString(k)
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data = append(data, byte(v))
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case int8:
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data = append(data, 1) // tagByte
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writeString(k)
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data = append(data, byte(v))
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case bool:
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b := 0
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if v {
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b = 1
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}
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data = append(data, 1) // tagByte
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writeString(k)
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data = append(data, byte(b))
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case uint16:
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data = append(data, 2) // tagInt16
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writeString(k)
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data = binary.LittleEndian.AppendUint16(data, uint16(v))
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case int16:
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data = append(data, 2) // tagInt16
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writeString(k)
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data = binary.LittleEndian.AppendUint16(data, uint16(v))
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case uint32:
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data = append(data, 3) // tagInt32
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writeString(k)
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data = binary.LittleEndian.AppendUint32(data, uint32(v))
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case int32:
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data = append(data, 3) // tagInt32
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writeString(k)
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data = binary.LittleEndian.AppendUint32(data, uint32(v))
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default:
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panic(fmt.Sprintf("unhandled nbt type: %T", v))
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}
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}
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data = append(data, 0) // end
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data = append(data, 0) // end
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return fnv1a.HashBytes32(data), data
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}
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