1 files changed, 51 insertions, 0 deletions
diff --git a/common/map.lua b/common/map.lua
index fe4b9e0..5bcd09e 100644
--- a/common/map.lua
+++ b/common/map.lua
@@ -3,4 +3,55 @@
 -- the specifics of which are then implemented separately for client and server
 -- it will probably also do things relating to entities and multiblock things
 
+local class = require"common.class"
+local chunk = require"common.chunk"
+local CHUNK_SIZE = require"common.constants".CHUNK_SIZE
 
+local Map = class()
+function Map.make(cls)
+	return setmetatable({chunks={}},cls)
+end
+function Map.add_chunk(self,cp,the_chunk)
+	print("adding chunk",cp)
+	assert(the_chunk.cp == cp,"attempting to add chunk with the wrong cp")
+	if not self.chunks[cp.u] then self.chunks[cp.u] = {} end
+	self.chunks[cp.u][cp.v] = the_chunk
+end
+function Map.unload_chunk(self,cp)
+	if not self.chunks[cp.u] then return end
+	self.chunks[cp.u][cp.v] = nil
+	-- remove list if empty
+	if next(self.chunks[cp.u]) == nil then self.chunks[cp.u] = nil end
+end
+function Map.chunk(self,cp)
+	-- return chunk at chunk coord cp
+	-- if that chunk isn't loaded return nil
+	return self:_chunkuv(cp.u,cp.v)
+end
+function Map._chunkuv(self,u,v)
+	-- same as above but with numbers instead of objects
+	-- to avoid allocations inside loop
+	return self.chunks[u] and self.chunks[u][v]
+end
+function Map.at(self,hpos)
+	-- returns tile at world coord hpos
+	-- if that tile's containing chunk isn't loaded, return nil
+
+	-- not using the methods for doing this, in order to avoid lots of allocations
+	-- inside the main drawing loop
+	local cpu,cpv = math.floor(hpos.q/CHUNK_SIZE),math.floor(hpos.r/CHUNK_SIZE)
+	local hoffq,hoffr = hpos.q-(cpu*CHUNK_SIZE), hpos.r-(cpv*CHUNK_SIZE)
+	local ch = self:_chunkuv(cpu,cpv)
+	if ch == nil then return nil end
+	return ch:_atqr(hoffq,hoffr)
+end
+function Map.set_at(self,hpos,tile)
+	local cp,hoffs = hpos:chunk_and_offset()
+	local ch = self:chunk(cp)
+	-- setting a tile in an unloaded chunk is silently ignored
+	-- this might change one day
+	if ch == nil then return nil end
+	ch:set_at(hoffs,tile)
+end
+
+return {Map=Map}