From b4c189ab1b6233c7e7e260446e80b789f375b5d6 Mon Sep 17 00:00:00 2001
From: ubq323 <ubq323@ubq323.website>
Date: Sat, 11 Feb 2023 15:33:13 +0000
Subject: change from random worldgen to be based on a hash of position;
 implement serverside chunk unloading

---
 client/main.lua     |  2 +-
 server/chunk.lua    |  3 ++-
 server/map.lua      |  5 +----
 server/noise.lua    | 24 ++++++++++++++++++++----
 server/server.lua   | 31 +++++++++++++++++++++++++------
 server/worldgen.lua | 18 +++++++++---------
 6 files changed, 58 insertions(+), 25 deletions(-)

diff --git a/client/main.lua b/client/main.lua
index a544250..03df16a 100644
--- a/client/main.lua
+++ b/client/main.lua
@@ -89,7 +89,7 @@ function love.update(dt)
 		update_local_player(local_player,dt)
 		if love.keyboard.isScancodeDown"q" then camera.zoom = camera.zoom*1.05 end
 		if love.keyboard.isScancodeDown"e" then camera.zoom = camera.zoom/1.05 end
-		camera.zoom = math.max(2.25,math.min(50,camera.zoom))
+		camera.zoom = math.max(1,math.min(50,camera.zoom))
 		sync_local_player(local_player)
 	end
 
diff --git a/server/chunk.lua b/server/chunk.lua
index 4fb2960..1e2e135 100644
--- a/server/chunk.lua
+++ b/server/chunk.lua
@@ -5,7 +5,7 @@ local json = require"common.dkjson"
 local ChunkS = class.extend(Chunk)
 function ChunkS.make(cls,...)
 	local self = Chunk.make(cls,...)
-	self.dirty = true
+	self.dirty = false
 	return self
 end
 function ChunkS.load_from_disk(cls,cp)
@@ -26,6 +26,7 @@ function ChunkS.save_if_dirty(self)
 		f:write(self:data_packet())
 		f:flush()
 		f:close()
+		self.dirty = false
 	end
 end
 function ChunkS.set_at(self,...)
diff --git a/server/map.lua b/server/map.lua
index 9627de9..3d7f377 100644
--- a/server/map.lua
+++ b/server/map.lua
@@ -29,15 +29,12 @@ function MapS.obtain(self,cp)
 	
 end
 function MapS.save_chunk(self,cp)
+	-- will only actually save anything if anything needs saving.
 	-- any attempt to save not-loaded chunks is silently ignored
 	local ch = self:chunk(cp)
 	if not ch then return end
 
 	ch:save_if_dirty()
 end
-function MapS.save_and_unload(self,cp)
-	self:save_chunk(cp)
-	self:remove_chunk(cp)
-end
 
 return {MapS=MapS}
diff --git a/server/noise.lua b/server/noise.lua
index fe254ac..bf7ac2e 100644
--- a/server/noise.lua
+++ b/server/noise.lua
@@ -1,13 +1,29 @@
 local Pos = require"common.coords".Pos
 local class = require"common.class"
+local bit = require"bit"
 local tau = 2*math.pi
 
 math.randomseed(os.time())
 
-local function random_unit_vec()
+
+local function hash_list(t)
+	local h = #t
+	for _,x in ipairs(t) do
+		x = bit.bxor(bit.rshift(x,16),x) * 0x45d9f3b
+		x = bit.bxor(bit.rshift(x,16),x) * 0x45d9f3b
+		x = bit.bxor(bit.rshift(x,16),x)
+		h = bit.bxor(h,x + 0x9e3779b9 + bit.lshift(h,6) + bit.rshift(h,2))
+	end
+	return h
+end
+
+local function hash_to_unit_vec(t)
+	local h = hash_list(t)
+	math.randomseed(h)
 	local theta = math.random()*tau
 	return Pos:make(math.cos(theta),math.sin(theta))
 end
+
 local function lerp(a,b,t) return (1-t)*a + t*b end
 local function smoothstep(x)
 	if x<0 then return 0 end
@@ -17,15 +33,15 @@ end
 local function slerp(a,b,t) return lerp(a,b,smoothstep(t)) end
 
 local PerlinNoise = class()
-function PerlinNoise.make(cls)
+function PerlinNoise.make(cls,ind_seed)
 	local grid = {}
 	setmetatable(grid,{__index=function(t,k) t[k] = {} return t[k] end})
-	return setmetatable({grid=grid},cls)
+	return setmetatable({grid=grid,ind_seed=ind_seed},cls)
 end
 function PerlinNoise.vertex(self,ix,iy)
 	local v = self.grid[ix][iy]
 	if v then return v end
-	local vv = random_unit_vec()
+	local vv = hash_to_unit_vec{ix,iy,self.ind_seed}
 	self.grid[ix][iy] = vv
 	return vv
 end
diff --git a/server/server.lua b/server/server.lua
index cc9903e..88f4efe 100644
--- a/server/server.lua
+++ b/server/server.lua
@@ -3,6 +3,7 @@ local json = require"common.dkjson"
 local chunk = require"common.chunk"
 local noise = require"noise"
 local coords = require"common.coords"
+local Pos = coords.Pos
 local worldgen = require"worldgen"
 local MapS = require"map".MapS
 local posix_time = require"posix.time"
@@ -34,7 +35,7 @@ local function random_color()
 	return {math.random(),math.random(),math.random()}
 end
 local function make_player(peer)
-	local p = {pos={0,0},color=random_color(),peer=peer,id=nextid}
+	local p = {pos=Pos:make(0,0),color=random_color(),peer=peer,id=nextid}
 	nextid = nextid + 1
 	return p
 end
@@ -42,8 +43,8 @@ end
 local function player_info_part(player)
 	return {
 		id=player.id,
-		x=player.pos[1],
-		y=player.pos[2],
+		x=player.pos.x,
+		y=player.pos.y,
 		color=player.color,
 	}
 end
@@ -95,8 +96,7 @@ local function handle_ev(ev)
 		local op = j.t
 		if op == "ppos" then
 			local x,y = j.x,j.y
-			player.pos[1] = x
-			player.pos[2] = y
+			player.pos = coords.Pos:make(x,y)
 			-- print(player.id,"-->",player.pos[1],player.pos[2])
 			for i,otherplayer in ipairs(playerlist) do
 				if otherplayer ~= player then
@@ -157,11 +157,30 @@ local ndts = 100
 local ntick = 0
 
 
+local function player_near_chunk(cp)
+	-- true: chunk at cp should stay loaded (because of a nearby player),
+	-- false: no players nearby, can be unloaded
+	-- this is kind of inefficient at the moment
+	for _,player in ipairs(playerlist) do
+		local pcp = player.pos:to_hex():containing_chunk()
+		for _,neighb in ipairs(pcp:neighborhood()) do
+			if neighb == cp then
+				return true
+			end
+		end
+	end
+	return false
+end
+
 local function tick(ntick)
 	if ntick % 30 == 0 then
-		print("saving things...")
+		print("saving things")
 		for cp,ch in map:iter_chunks() do
 			map:save_chunk(cp)
+			if not player_near_chunk(cp) then
+				print("unloading chunk",cp)
+				map:remove_chunk(cp)
+			end
 		end
 	end
 end
diff --git a/server/worldgen.lua b/server/worldgen.lua
index 2ef1ac0..0a8485b 100644
--- a/server/worldgen.lua
+++ b/server/worldgen.lua
@@ -4,18 +4,18 @@ local chunk = require"common.chunk"
 local ChunkS = require"chunk".ChunkS
 local CHUNK_SIZE = require"common.constants".CHUNK_SIZE
 
-local function p(amp,scale) return {scale=scale,amp=amp,gen=noise.PerlinNoise:make()} end
--- local ng = noise.NoiseAgg:make{
--- 	p(1,20),
--- 	-- p(0.7,2),
--- 	p(0.5,15),
--- 	--p(2,200),
--- }
+local function p(amp,scale,seed)
+	return {
+		scale=scale,
+		amp=amp,
+		gen=noise.PerlinNoise:make(seed)
+	}
+end
 
 -- whether there is a tile there or not
-local surface_ng = noise.NoiseAgg:make{p(1,20),p(0.5,15)}
+local surface_ng = noise.NoiseAgg:make{p(1,20,1),p(0.7,5,2)}
 -- if there is a tile there, what color should it be
-local color_ng = noise.NoiseAgg:make{p(1,20),p(0.5,15)}
+local color_ng = noise.NoiseAgg:make{p(1,20,3),p(0.5,15,4)}
 
 
 local function gen_chunk(chpos)
-- 
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