VXOR unminified & commented source code

vxor.p8

--vxor by eric billingsley
--released under cc by-nc-sa 4.0

--shift selection with wrapping (selection, board, and goal are each
--respresented as numbers, using 25 bits to represent the board positions)
function shift(button,mask,shiftamount)
	--bitshift the selection. use a mask to shift the wrapping row/column
	--separately and in the opposite direction by 4
	if (getinput(button)) selection=(selection&~mask)>>>shiftamount|(selection&mask)<<shiftamount*4
end

--make moves based on inputs
function makemoves()
	shift(0,0x8421.08,-1)--left
	shift(1,0x842.108,1)--right
	shift(2,-2048,-5)--up
	shift(3,.06055,5)--down
	
	--xor selection with board
	--when pressing ❎
	if (getinput(5)) board^^=selection
end

level=0

--generic draw board function, taking in a bitfield
--representing the positions to draw
function draw(board,glyph,colour)
	for i=0,24 do
		--if bit is set, calculate position based on index and draw glyph there
		if (board&1<<15-i!=0) ?glyph,43+i%5*9,y+i\5*9,colour
	end
end

::initlevel::

--every 5 levels, reset state to a single center light (board state 8)
--so things don't get out of control too quickly. also switch the colour
if (level%5==0) board=8 colour=9+level%6

--on new level, generate a random sound
--(gets a bit more complex-sounding at higher levels)
sound=rnd(level)

selection=board
level+=1

--while generating level, override getinput to be random
getinput=function()
	--this probability gets higher as levels increase in order to generate
	--more complex puzzles. things will break as the number reaches 0 at
	--level 256 which is not ideal...
	return rnd()>.96^level
end

initialstate=board

::generationloop::
	--make a move with random inputs
	makemoves()
	--continue looping until the board is different from initial state and
 	--not empty. also loop back if we get a	positive result from getinput(),
	--which is a random probability that increases with level number.
 	--this means later levels tend to require more steps.
	if(getinput() or board==0 or initialstate==board)goto generationloop

--now that the level is generated, set the board to initial state
--and set getinput to actually check button presses
goal=board
selection=initialstate
board=initialstate
getinput=btnp

::mainloop::

--if we have a sound, play it using a print command. the g is added
--because it sounds nice. ideally would also like to turn on reverb level 1
--using poke, but don't have the chars...
if(sound>0)?"⁷g"..sound

--refresh the screen & inputs
flip()
cls()

--print level number in top corner
?level
--if any button is pressed, a sound is generated based on the bitfield.
--3.5 was chosen through trial & error because it produced good sounds
sound=getinput()*3.5

--set vertical draw position for top board
y=13

--this string prints as a 7x7 circle outline,
--used to draw the grid & selection
o="(ᵇ~ノᵇk-)"

makemoves()

--reset puzzle when 🅾️ pressed.
--ideally we would reset selection also but don't have the characters.
if(getinput(4))board=initialstate

--draw top board
draw(~0,o,1)--grid (~0 is all 1s)
draw(board,"●",colour)--lights
draw(selection,o,7)--selection (white circle outlines)

--if we have the solution, generate a new puzzle.
--since we haven't drawn the bottom board yet, it will flash black
--for a frame, which gives some feedback to the player
if(board==goal)goto initlevel

--draw bottom board
y=73
draw(~0,o,1)--grid
draw(goal,"●",12)--lights

goto mainloop