Create JoypadIntersection.lua

Adds a small script which, when run, only allows input to P1's controller if both P1 and P2 holds down the specific button simultaneously. Also useful since it demonstrates joypad manipulation.

Assets/Lua/JoypadIntersection.lua

@@ -0,0 +1,57 @@
+---------------------------------------------------------
+-- Small script for only allowing input on P1 controller
+-- if both P1 and P2 holds down a specific input
+--
+-- Note that this script only works on systems which
+-- has two or more joypads (such as NES) and not on
+-- systems with just one joypad (such as Gameboy)
+--
+-- Author: Gikkman
+---------------------------------------------------------
+
+-- Pre-made array for resetting the P1 joypad
+local reset = joypad.get(1)
+for k,v in pairs(reset) do
+    reset[k] = ''
+end
+
+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 )
+ 
+event.onframeend( function()	
+    joypad.set(reset, 1)
+end )
+ 
+-- Get intersection of P1 and P2 joypads
+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