Devil Island - Hitboxes and Watches v1.3

--Hitboxes and Watches v1.3 for GBC Devil Island (Emo Dao) by ThunderAxe31

local R2ub= memory.read_u16_be
local R2ul= memory.read_u16_le
local R1u= memory.read_u8

local white = 0xFFFFFFFF
local black = 0xFF000000

local player_x = R1u(0xD001)
local actions  = R1u(0xD008)

local combined_x_old = -1
local combined_x_lagcount = 0
local framecount_old = -1

local function draw_watches()
    local combined_x = player_x + R2ul(0xC122) --add level x

    --count x lag
    local framecount = emu.framecount()
    if framecount_old ~= (framecount-1) then --if a state has been loaded, reset values
        combined_x_lagcount = 0
        combined_x_old = -1
    end
    if (combined_x_old > -1) and (combined_x_old == combined_x) then --checks if the x value is unchanged
        combined_x_lagcount = combined_x_lagcount + 1 --updates the movement lag count
        if combined_x_lagcount > 9999 then --reset counter
            combined_x_lagcount = 0
        end
    end
    combined_x_old = combined_x --updates the x value
    framecount_old = framecount --updates the frame count

    --exp stuff
    local exp_amount = R2ub(0xCFF8)
    local exp_next = 0
    local attack = 0
    if exp_amount < 3072 then
        attack = 1
        exp_next =  3072 - exp_amount
    elseif exp_amount <  6144 then
        attack = 2
        exp_next =  6144 - exp_amount
    elseif exp_amount <  8192 then
        attack = 3
        exp_next =  8192 - exp_amount
    elseif exp_amount < 10240 then
        attack = 4
        exp_next = 10240 - exp_amount
    elseif exp_amount < 12288 then
        attack = 5
        exp_next = 12288 - exp_amount
    elseif exp_amount < 14336 then
        attack = 6
        exp_next = 14336 - exp_amount
    elseif exp_amount < 16384 then
        attack = 7
        exp_next = 16384 - exp_amount
    else
        attack = 8
        exp_next = 0
    end

    --display watches
    if bit.band(actions, 128) ~= 128 then --if menu is open, don't display.
        gui.pixelText(0, 0, "X_POS:     EXP:      ATK: \nX_LAG:     NEXT:     HP:",  white, black)
        gui.pixelText(24, 0, string.format("%4s", combined_x), white, black) --current X position in level
        gui.pixelText(24, 7, string.format("%4s", combined_x_lagcount), white, black) --current movement X lag counted
        gui.pixelText(60, 0, string.format("%5s", exp_amount), white, black) --experience total
        gui.pixelText(64, 7, string.format("%4s", exp_next), white, black) --experience left for next level
        gui.pixelText(100,0, attack, white, black) --attack level
        gui.pixelText(96, 7, string.format("%2s", R1u(0xCFF5)),  white, black) --player HP
        gui.pixelText(108, 0, "$:" .. R2ul(0xCFF6), white, black) --money
    end
end

local function fix_negative(value) --wrap negative coordinates correctly
    if (value>212) then
        return value-256
    end
    return value
end

local function enemy_hitboxes()
    for i = 0, 3 do --yes, there are just 4 object slots
        local addr = 0xC200+i*0x20 --data chunks for objects are 32 bytes long
        if R1u(addr) ~= 0 then --enemy hitboxes
            gui.drawRectangle(fix_negative(R1u(addr+0x01))+R1u(addr+0x12)-8, fix_negative(R1u(addr+0x02))+R1u(addr+0x14)-16, R1u(addr+0x13)-1, R1u(addr+0x15)-1)
            local obj_type = R1u(addr+0x16)
            local label = ""
            if obj_type==0 then --if enemy, show HP
                if R1u(addr+0x0F)~=255 then
                    label = R1u(addr+0x07)
                end
            elseif obj_type==1 then --if money, show how much
                label = "$"..R1u(addr+0x17)
            elseif obj_type==2 then --if health, display a simple hospital cross
                label = "+"
            elseif obj_type==3 then --if pass
                label = "PASS"
            elseif obj_type==4 then --if whip piece
                label = "WHIP\nPIECE"
            else --if unknown, just in case
                label = "?"
            end
            gui.pixelText(fix_negative(R1u(addr+0x01))-7, fix_negative(R1u(addr+0x02))-15, label, white, black)
        end
    end

    --since there is currently no better solution, we're simply gonna splat these bosses HP on the screen upper left...
    local head_hp = R1u(0xC1B3)
    local core_hp = R1u(0xC1B4)
    local boss_hp = R1u(0xC1A5)
    if head_hp > 0 then
        gui.pixelText(0, 14, "HEAD HP: " .. head_hp, white, black)
    end
    if core_hp > 0 then
        gui.pixelText(0, 21, "CORE HP: " .. core_hp, white, black)
    end
    if boss_hp > 0 then
        gui.pixelText(0, 28, "BOSS HP: " .. boss_hp, white, black) --using a different Y cooradinate, just in case
    end --and no, all other bosses use the regular enemy object structure. this would explain why only these three have an invicibility timer.
end

local function player_hitboxes()
    local player_y = R1u(0xD000)
    local whip_x = player_x + 8
    local whip_y = player_y - 8
    local player_height = 32
    local whip_height   = 32

    if bit.band(actions, 4) == 4 then --if crouched
        player_y = player_y + 8
        player_height = 24
        whip_y = whip_y + 8
        whip_height = 40
    end

    gui.drawRectangle(player_x, player_y, 16, player_height) --player hitbox

    if bit.band(actions, 2) == 2 then --if attacking
        if R1u(0xD005) == 2 then --if facing left
            whip_x = whip_x -16
        end
        gui.drawRectangle(whip_x, whip_y, 16, whip_height) --whip hitbox
    end
end

while true do
    player_x = R1u(0xD001)
    actions  = R1u(0xD008)

    draw_watches()
    enemy_hitboxes()
    player_hitboxes()

    emu.frameadvance()
end