Posted: 10/14/2018 8:08 PM
Post subject: Lua manipulation of joypad
Quote
Gikkman
Joined: 12/9/2010
Posts: 3
Location: Falun, Sweden
Hi. I tinkered around a bit with the Lua scripts, and came up with an idea I tried to implement. The idea is to take the intersection between button presses on controller 1 and button presses on controller 2, and only pass that as the input to controller 1. In essence, both players has to play at the same time. But I ran into a problem: if I set the joypad of controller 1, the next frame I can only retrieve what I assigned to the joypad the previous frame (this is made clear in the documentation too). So, I was wondering, is it possible to access the raw input from both players, and not the joypad state as seen by the emulator? Here is my current script: 
Language: lua
-- Filter out the input on a certain player
function split(player, joypad) 
	local ret = {}
	for k,v in pairs(joypad) do
		if k:sub(1,2) == player then ret[k:sub(4)]=v end
	end
	return ret
end

function intersection(p1, p2)
	local ret = {}
	for k,v in pairs(p1) do
		ret[k]= p1[k] and p2[k]
	end
	return ret
end

-- Make string from all pressed buttons
function dump(o)
  local s = ''
  for k,v in pairs(o) do
	 if v then s = s .. tostring(k) .. ' ' end
  end
  return s
end

while true do
	-- Read the current joypad state
	local pad = joypad.getimmediate()
	-- Split the input for player 1 and player 2
	local p1 = split("P1", pad)
	local p2 = split("P2", pad)
	-- Find the intersection between the two
	local inter = intersection(p1, p2)
	
	-- Render some help text
	gui.drawText(0,10, "P1: " .. dump(p1), null, null, 10)
	gui.drawText(0,25, "P2: " .. dump(p2), null, null, 10)
	gui.drawText(0,40, "Out: " .. dump(inter), null, null, 10)
	
	-- Set joypad 1 to the intersection of the two
	joypad.set(inter, 1)
	
	emu.frameadvance()
end
Thanks!
Geez... I've been gone a long time and not a single new post in the ZSNES forum... :'-(
Posted: 10/21/2018 3:17 PM
Quote
Gikkman
Joined: 12/9/2010
Posts: 3
Location: Falun, Sweden
I've done quite some research by now, and asked several questions on IRC too, but I am still drawing up short. So far, it looks like the problem I have might be that you cannot really un-set button presses via the Lua script. This thread seems to suggest that there was some issues with passing false as a button press to the joypad.set method. The thread mentioned that the issue should be fixed soon, but I am not sure if that was ever done. Also, this Github issue mentions that joypad.set cannot be used to un-set buttons, which seems to be in line with my findings too. Both these sources are very old though, so I am not sure if these issues should have been fixed (or if they are even issues at all, it might be by design). Is it possible today to somehow un-set buttons pressed on the joypad?
Geez... I've been gone a long time and not a single new post in the ZSNES forum... :'-(
Posted: 10/22/2018 6:39 PM
Quote
Gikkman
Joined: 12/9/2010
Posts: 3
Location: Falun, Sweden
After some detective work from zeromus (as reported in this thread) I got the script working as intended. My full script now is: 
Language: lua
local reset = joypad.get(1)
for k,v in pairs(reset) do
	reset[k] = ""
end

-- Set P1 to intersection of P1 and P2
event.onframestart( function()
    local p1 = joypad.get(1)
    local p2 = joypad.get(2)
    local consolidated = intersection(p1, p2)
	
	gui.drawText(0,10, "P1: " .. dump(p1))
    gui.drawText(0,25, "P2: " .. dump(p2))
	
	joypad.set(consolidated,1);
end )
 
 -- Reset P1
event.onframeend( function()	
	joypad.set(reset, 1)
end )
 
-- Set each button to pressed only if it is pressed by
-- by both players
function intersection(p1, p2)
    local ret = {}
    for k,v in pairs(p1) do
        ret[k] = p1[k] and p2[k]
	end
    return ret
end
 
-- Print all pressed buttons
function dump(o)
  local s = ''
  for k,v in pairs(o) do
     if v then s = s .. tostring(k) .. ' ' end
  end
  return s
end
 
-- Main loop
while true do
    emu.frameadvance()
end
Geez... I've been gone a long time and not a single new post in the ZSNES forum... :'-(