Merge pull request #3 from nathyong/feature/nathyong/tetrax-randomizer

Add the Tetra Legends Tetra-X randomizer
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Ishaan Bhardwaj 2020-12-02 21:21:23 -05:00 committed by GitHub
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-- A randomizer based on Tetra Legends' "Tetra-X" game mode
-- There are two main rules:
-- * if piece hasn't been generated for 13+ pieces, force it
-- * if piece has been generated in the last two pieces, don't give it out
--
-- The official implementation also has self-balancing functionality (bias
-- towards pieces that have appeared less often).
local Randomizer = require 'tetris.randomizers.randomizer'
local TetraXRandomizer = Randomizer:extend()
function TetraXRandomizer:initialize()
local pieces = {"I", "J", "L", "O", "S", "T", "Z"}
self.count = {}
self.lastseen = {}
self.totalcount = 0
self.pieceselection = pieces
for _, piece in ipairs(pieces) do
self.count[piece] = 0
self.lastseen[piece] = -1 -- use -1 as magic value for "not seen"
end
end
function TetraXRandomizer:generatePiece()
local generated = nil
while true do
generated = self.pieceselection[math.random(#self.pieceselection)]
if not (self.lastseen[generated] == 0 or self.lastseen[generated] == 1) then
break
end
end
-- piece has not been generated in the last 13+
for piece, val in pairs(self.lastseen) do
if val >= 13 then
generated = piece
break
end
end
for piece, val in pairs(self.lastseen) do
if piece == generated then
self.lastseen[piece] = 0
else
if val ~= -1 then
self.lastseen[piece] = val + 1
end
end
end
self.count[generated] = self.count[generated] + 1
self.totalcount = self.totalcount + 1
-- shuffle the piece selection for the next time
self.pieceselection = {}
for piece, count in pairs(self.count) do
-- in this case 6 = #piece types - 1, so all probabilities sum to 1
local probability = (self.totalcount - count) / (self.totalcount * 6)
local chances = math.floor(probability * 1000 + 0.5) -- simulated "round"
for _ = 1, chances do
table.insert(self.pieceselection, piece)
end
end
return generated
end
return TetraXRandomizer