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local class = require"common.class"
local CHUNK_SIZE = require"common.constants".CHUNK_SIZE
-- Hex: q,r,s. invariant that q+r+s=0
-- add, subtract
-- constructor takes 3 positions and rounds to closest hex centre.
-- round to nearest int, rounding .5 away from 0.
local function round(x)
if x<0 then
return math.ceil(x-0.5)
else
return math.floor(x+0.5)
end
end
local Pos, Hex, ChunkPos
local SR3 = math.sqrt(3)
Hex = class()
function Hex.new(cls)
return setmetatable({},cls)
end
function Hex.init(self,q,r,s)
s=s or -q-r
assert(q+r+s==0,"hex coord doesn't meet invariant")
self.q=q
self.r=r
self.s=s
return self
end
function Hex.make(cls,...)
return cls:new():init(...)
end
function Hex.round(self)
-- return a new Hex rounded to integer coordinates
local fq,fr,fs = self.q,self.r,self.s
-- round all to nearest integer
-- find which was changed the most, reset that one to be coherent with the other two.
local abs = math.abs
local rq,rr,rs = round(fq),round(fr),round(fs)
local dq,dr,ds = abs(fq-rq), abs(fr-rr), abs(fs-rs)
if dq>dr and dq>ds then
rq = -rr-rs
elseif dr>ds then
rr = -rq-rs
else
rs = -rq-rr
end
return Hex:make(rq,rr,rs)
end
function Hex.to_pos(self,into)
into = into or Pos:new()
local x = self.q*SR3 + self.r*(SR3/2)
local y = self.r*(3/2)
return into:init(x,y)
end
function Hex.containing_chunk(self)
local u = math.floor(self.q/CHUNK_SIZE)
local v = math.floor(self.r/CHUNK_SIZE)
return ChunkPos:make(u,v)
end
function Hex.chunk_and_offset(self)
local cp = self:containing_chunk()
local tl = cp:extents()
return cp, (self-tl)
end
function Hex.offset_in_chunk(self)
local cp,offs = self:chunk_and_offset()
return offs
end
function Hex.__add(self,other) return Hex:make(self.q+other.q, self.r+other.r, self.s+other.s) end
function Hex.__sub(self,other) return Hex:make(self.q-other.q, self.r-other.r, self.s-other.s) end
function Hex.__tostring(self) return string.format("H(%.2f,%.2f)",self.q,self.r) end
function Hex.__eq(a,b) return a.q==b.q and a.r==b.r end
Pos = class()
function Pos.new(cls)
return setmetatable({},cls)
end
function Pos.init(self,x,y)
self.x = x
self.y = y
return self
end
function Pos.make(cls,...)
return cls:new():init(...)
end
function Pos.__add(self,other) return Pos:make(self.x+other.x,self.y+other.y) end
function Pos.__sub(self,other) return Pos:make(self.x-other.x,self.y-other.y) end
function Pos.__mul(a,b)
if type(a) == "number" then
return Pos:make(a*b.x,a*b.y)
elseif type(b) == "number" then
return Pos:make(a.x*b,a.y*b)
else
error("can only multiply Pos by scalar")
end
end
function Pos.__div(a,b)
assert(type(b) == "number","can only divide Pos by scalar, and can't divide scalar by Pos")
return a*(1/b)
end
function Pos.__eq(a,b) return a.x==b.x and a.y==b.y end
function Pos.lensq(self) return self.x^2 + self.y^2 end
function Pos.len(self) return math.sqrt(self:lensq()) end
function Pos.norm(self) return self/self:len() end
function Pos.dot(self,other) return self.x*other.x + self.y*other.y end
function Pos.to_hex(self,into)
into = into or Hex:new()
local q = self.x*(SR3/3) - self.y*(1/3)
local r = (2/3)*self.y
return into:init(q,r,-q-r)
end
function Pos.__tostring(self) return string.format("(%.2f,%.2f)",self.x,self.y) end
-- represents coordinates of a chunk
-- ie pair of integers. the chunk at spawn is C(0,0), the one to the right of that is C(1,0), etc
ChunkPos = class()
function ChunkPos.make(cls,u,v)
return setmetatable({u=u,v=v},cls)
end
function ChunkPos.__add(self,other) return ChunkPos:make(self.u+other.u,self.v+other.v) end
function ChunkPos.__sub(self,other) return ChunkPos:make(self.u-other.u,self.v-other.v) end
function ChunkPos.__tostring(self) return string.format("C(%d,%d)",self.u,self.v) end
function ChunkPos.__eq(a,b) return a.u==b.u and a.v==b.v end
function ChunkPos.extents(self)
-- returns Hex of topleft and bottomright
local tlq,tlr = self.u*CHUNK_SIZE, self.v*CHUNK_SIZE
local brq,brr = (self.u+1)*CHUNK_SIZE -1, (self.v+1)*CHUNK_SIZE -1
return Hex:make(tlq,tlr), Hex:make(brq,brr)
end
function ChunkPos.filename(self)
-- filename of chunk with that cp
return "world/c_"..self.u.."_"..self.v..".dat"
end
return {Hex=Hex,Pos=Pos,ChunkPos=ChunkPos}
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