diff options
Diffstat (limited to 'common')
| -rw-r--r-- | common/chunk.lua | 5 | ||||
| -rw-r--r-- | common/rle.lua | 50 |
2 files changed, 53 insertions, 2 deletions
diff --git a/common/chunk.lua b/common/chunk.lua index 39fcaaf..563723e 100644 --- a/common/chunk.lua +++ b/common/chunk.lua @@ -1,6 +1,7 @@ local json = require"common.dkjson" local class = require"common.class" local coords = require"common.coords" +local rle = require"common.rle" local CHUNK_SIZE = require"common.constants".CHUNK_SIZE @@ -32,14 +33,14 @@ function Chunk.set_at(self,hoffs,tile) end function Chunk.data_packet(self) - return json.encode{t="chunk",tiles=self.tiles,u=self.cp.u,v=self.cp.v} + return json.encode{t="chunk",tiles=rle.encode(self.tiles),u=self.cp.u,v=self.cp.v} end function Chunk.from_packet_data(cls,packet) -- assuming packet has already been json.decoded -- since otherwise how would we know it's a chunk packet local cp = coords.ChunkPos:make(packet.u,packet.v) - return cls:make(cp,packet.tiles) + return cls:make(cp,rle.decode(packet.tiles)) end return { diff --git a/common/rle.lua b/common/rle.lua new file mode 100644 index 0000000..2944c4c --- /dev/null +++ b/common/rle.lua @@ -0,0 +1,50 @@ +-- run length encoding + +local function encode(l) + local out = {} + + local last = l[1] + local count = 1 + + local function ap() + if count == 1 then + table.insert(out,last) + elseif count == 2 then + table.insert(out,last) + table.insert(out,last) + else + table.insert(out,{count,last}) + end + end + + for ix=2,#l do + local val = l[ix] + if val == last then + count = count + 1 + else + ap() + last = val + count = 1 + end + end + + ap() + + return out +end + +local function decode(l) + local out = {} + for _,r in ipairs(l) do + if type(r) == "table" and #r == 2 then + for i = 1,r[1] do + table.insert(out,r[2]) + end + else + table.insert(out,r) + end + end + return out +end + +return {encode=encode,decode=decode} |