Marble Madness Camera Hack (Lua Script)

--Marble Madness camhack script for Aglar's run.
--Script by TheAxeMan
--
--I usually put the rewind code in a separate module but combined it here for distribution.
--
--This module is designed to provide "frame rewind" where
--holding down R and pressing frame advance once will bring
--you back one frame. You should be able to pick up from
--there with no trouble.

messagesToDisplay = {}
dispCount = 0
newframe = false

gui.register(
function()
  dispCount = dispCount+1
  for i,m in pairs(messagesToDisplay) do
    gui.text(m.x, m.y, m.text)
  end;
  newframe = false
end
)

local function addMessage(x, y, text)
  table.insert(messagesToDisplay, {x=x, y=y, text=text})
end;
local function clearMessages()
  messagesToDisplay = {}
end;

local function readRewindButton()
  keysPressed = input.get()
  return keysPressed["R"];
end;


rewindSaveStateBuffer = {}
rewindInputBuffer = {}
rewindBufferDepth = 0
rewindLastFramecount = movie.framecount()
--This gets set to "rewind" when rewinding
rewindLastFrameAction = "advance"


function manageRewind()
  if readRewindButton() then
    if rewindBufferDepth > 2 then
      addMessage(10,10, "rewinding")
      local loadIndex = movie.framecount()-2
      savestate.load(rewindSaveStateBuffer[loadIndex])
      joypad.set(1, rewindInputBuffer[loadIndex+1])
      rewindBufferDepth = rewindBufferDepth-1
      --FCEU.frameadvance()
      --clearMessages()
      --newframe=true
    elseif rewindBufferDepth <= 2 then
      local loadIndex = movie.framecount()-1
      savestate.load(rewindSaveStateBuffer[loadIndex])
      --joypad.set(1, rewindInputBuffer[loadIndex])
      addMessage(10,10, "end of buffer")
    end;
  else
    --Add to buffer
    local bufferIndex = movie.framecount()
    if rewindSaveStateBuffer[bufferIndex] == nil then
      rewindSaveStateBuffer[bufferIndex] = savestate.create()
    end;
    savestate.save(rewindSaveStateBuffer[bufferIndex])
    rewindInputBuffer[bufferIndex] = joypad.read(1)
    rewindBufferDepth = rewindBufferDepth + 1

  end;
  addMessage(10,20, "Buffer depth is "..rewindBufferDepth)

end;


function frameAdvanceWithRewind()
  FCEU.frameadvance()
  manageRewind();
  clearMessages()
  newframe=true
end;
function pauseWithRewind()
  FCEU.pause()
  manageRewind();
end;

FCEU.pause()

while true do
  --Aggressively move screen down
  scrollpos = 50
  --Be less aggressive at beginning of intermediate race
  if movie.framecount() > 3050 and movie.framecount() < 3480 then scrollpos=100 end;
  --Don't do this during part of aerial race
  if movie.framecount() > 5100 and movie.framecount() < 5460 then scrollpos=300 end;
  --if movie.framecount() > 5100 and movie.framecount() < 6000 then scrollpos=300 end;
  --In the Silly race everything you know is wrong
  if movie.framecount() > 6500 and movie.framecount() < 7800 then scrollpos = 300 end;
  --Disable during Ultimate race to avoid desync
  if movie.framecount() > 8400 then scrollpos=300 end;

  relpos = memory.readbyte(0x0450)
  if relpos > scrollpos then
    memory.writebyte(0x0450, 155)
  end;

  --Special aerial fix
  if movie.framecount() == 5500 then
    memory.writebyte(0x00A0, 0x33)
  end;

  --In the Silly race everything you know is wrong
  if movie.framecount() > 6500 and movie.framecount() < 7800 then
      --This forces screen to just keep scrolling.
      memory.writebyte(0x0458, 127)
  end;

  frameAdvanceWithRewind()
end;