Mask

local camx
local camy
function findbit(p)
    return 2 ^ (p - 1)
end

function hasbit(x, p)
    return x % (p + p) >= p
end

local function hex(val)
    val = string.format("%X",val)
    if string.len(val) == 1 then
        val = "0" .. val
    end
    return val
end

local function camera()
    camx = memory.readword(0x47)
    camy = memory.readword(0x4F)
end

local function drawbox(x1,x2,y1,y2,outl,fill)
    gui.box(x1,y1,x2,y2,outl,fill)
end

local function player()
    local x = memory.readword(0x185C) - camx
    local y = memory.readword(0x1860) - camy

    memory.registerexec(0x80B3F7, function()
            if memory.getregister("Y") == 0x1858 then -- is player
                local x1 = memory.readword(0x7B) -camx
                local x2 = memory.readword(0x7D) -camx
                local y1 = memory.readword(0x7F) -camy
                local y2 = memory.readword(0x81) -camy
                drawbox(x1,x2,y1,y2,"#0000FF40","#0000FFFF")
            end
    end)
end

local function enemies()
    memory.registerexec(0x80AD32, function()

        if hasbit(memory.readword(0x1E + memory.getregister("Y")),findbit(15)) then
            local flip = true
        else
            local flip = false
        end

        local x = memory.readword((memory.getregister("DB") * 0x10000) + 4 + memory.getregister("Y")) -camx
        local y = memory.readword((memory.getregister("DB") * 0x10000) + 8 + memory.getregister("Y")) -camy

        local x1 = memory.readword(0x77) -camx
        local x2 = memory.readword(0x79) -camx
        local y1 = memory.readwordsigned(0x838002 + memory.getregister("X")) + y
        local y2 = memory.readwordsigned(0x838006 + memory.getregister("X")) + y

        drawbox(x1,x2,y1,y2,"#FF000040","#FF0000FF")
    end)
end

local function test()
    --memory.writeword(0x7E2b96,1240)
end

while true do
    camera()
    player()
    enemies()
    test()
    emu.frameadvance()
end