chunk2d.lua

--[[
	MIT License

	Copyright (c) 2019 Guthen

	Permission is hereby granted, free of charge, to any person obtaining a copy
	of this software and associated documentation files (the "Software"), to deal
	in the Software without restriction, including without limitation the rights
	to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
	copies of the Software, and to permit persons to whom the Software is
	furnished to do so, subject to the following conditions:

	The above copyright notice and this permission notice shall be included in all
	copies or substantial portions of the Software.

	THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
	IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
	FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
	AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
	LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
	OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
	SOFTWARE.
]]--

module( "Chunk2D", package.seeall )

author = "Guthen"
version = "1.0.0"

local seed = 0
local cellSize = 8
local chunkW, chunkH = 600, 800 
local surfaceY = 30
local minSurfaceY = chunkH/cellSize - 15
local maxSurfaceY = 5
local fillIDs = 
	{
		[1] = 1,
		[2] = 2,
	}

math.randomseed( seed )

--[[-------------------------------------------------------------------------
	--  > get config
---------------------------------------------------------------------------]]

function getSeed()
	return seed
end

function getCellSize()
	return cellSize
end

function getChunkSize()
	return chunkW, chunkH
end

function getSurfaceValues()
	return surfaceY, minSurfaceY, maxSurfaceY
end

function getFillSurfaces()
	return fillIDs
end

--[[-------------------------------------------------------------------------
	--  > config
---------------------------------------------------------------------------]]

function set( _seed, _cellSize, _chunkW, _chunkH, _startY, _minY, _maxY )
	seed = _seed or seed
	cellSize = _cellSize or cellSize
	chunkW = _chunkW or chunkW
	chunkH = _chunkH or chunkH
	surfaceY = _startY or surfaceY
	minSurfaceY = _minY or minSurfaceY
	maxSurfaceY = _maxY or maxSurfaceY

	if _seed then
		math.randomseed( seed )
	end
end

function setFillID( _IDs )
	fillIDs = _IDs or fillIDs
end

--[[-------------------------------------------------------------------------
	--  > chunks & world
---------------------------------------------------------------------------]]

--  > Create Empty Chunk 
function createEmptyChunk()
	local _chunk = {}
	for y = 0, chunkH/cellSize do
		_chunk[y] = {}
		for x = 0, chunkW/cellSize do
			_chunk[y][x] = 0
		end
	end
	return _chunk
end

--  > Get SurfaceY Position of the '_chunk' by given '_x' 
function getSurfaceY( _chunk, _x )
	if _x < 0 then return end
	for y, yv in pairs( _chunk ) do
		for x, xv in pairs( yv ) do
			if _x == x then
				if xv > 0 then return y end
			end
		end
	end
end

--  > Create & Generate a chunk by using the '_lastChunk'
function generateChunk( _chunk, _lastChunk )
	local function fillChunk()
		for x = 0, chunkW/cellSize do
			local y = getSurfaceY( _chunk, x )

			if y then
				local b = 0
				local surface = fillIDs[2] 
				for _y = y+1, H/cellSize do 
	 				_chunk[_y][x] = surface
		 			b = b + 1
		 			if b > 1 and fillIDs[b] then
		 				surface = fillIDs[b]
		 			end
		 		end
		 	end
		end
	end

	for x = 0, chunkW/cellSize do -- generate the surface
		
		local _y
		if _lastChunk and x == 1 then
			_y = getSurfaceY( _lastChunk, chunkW/cellSize )
		else
			_y = getSurfaceY( _chunk, x-1 )
		end

		if _y then
			local offset = math.random( -1, 1 ) -- get the Y offset
			if _chunk[_y + offset] and _chunk[_y + offset][x] then -- if it's exists
				if _y + offset < maxSurfaceY or _y + offset > minSurfaceY then
					offset = 0
				end
				_chunk[_y + offset][x] = fillIDs[1]
			end
		elseif not _lastChunk then
			_chunk[surfaceY][x] = fillIDs[1]
		end

	end

	smoothChunk( _chunk, _lastChunk )
	fillChunk()
end

--  > Create & Generate a world of 'nChunks' chunks
function generateWorld( nChunks )
	local world = {}
	for i = 1, nChunks do
		world[i] = createEmptyChunk()
		generateChunk( world[i], world[i-1] )
	end
	return world
end

--  > Smooth the chunk
function smoothChunk( _chunk, _lastChunk )
	for x = 0, chunkW/cellSize do -- smoothness

		local activeChunk = _chunk

		local y, _y, __y, ___y
		y = getSurfaceY( _chunk, x )

		if _lastChunk and not _chunk[x-1] then
			_y = getSurfaceY( _lastChunk, chunkW/cellSize-1 )
			activeChunk = _lastChunk
		else
			_y = getSurfaceY( _chunk, x-1 )
		end
		if _lastChunk and not _chunk[x-2] then
			__y = getSurfaceY( _lastChunk, chunkW/cellSize-2 )
			activeChunk = _lastChunk
		else
			__y = getSurfaceY( _chunk, x-2 )
		end
		if _lastChunk and not _chunk[x-3] then
			___y = getSurfaceY( _lastChunk, chunkW/cellSize-3 )
			activeChunk = _lastChunk
		else
			___y = getSurfaceY( _chunk, x-3 )
		end

		if y and _y and __y then
			if y == __y and not (_y == y) and math.abs( y - _y ) <= 1 and activeChunk[y] then -- if : '0 - 1 - 0' or : '1 - 0 - 1'
				if _y and y and _y < y then activeChunk[_y][x-1] = 0 end
				activeChunk[y][x-1] = 1
			elseif y == ___y and _y == __y and not y == _y then
				activeChunk[y][x-1] = 2
				activeChunk[y][x-2] = 2
			end
		end

	end
end

-- Smooth all of the world chunks 
function smoothWorld( world )
	for id = 1, #world do -- smoothness
		local curChunk = world[id]
		local lastChunk = world[id-1]

		smoothChunk( curChunk, lastChunk )
	end
end