Castlevania Collision box viewer (BIZHAWK)

local px = 0x38C
local py = 0x354
local pl = 0x45

local ex = 0x38C
local ey = 0x354

memory.usememorydomain("PRG ROM")

local function whip()
    local box = {0,0,0} -- xoff/yoff/xrad/yrad
    local wtype = mainmemory.read_u8(0x70)
    local pos = bit.band(mainmemory.read_u8(0x434),0x7F)  -- Simons acting positon (jumping/crouching, etc...)
    box[1] = memory.read_s8(0x1E45D + wtype)
    wtype = wtype * 2
    box[2] = memory.read_s8(0x1E460 + pos)
    box[3] = memory.read_u8(0x1E464 + wtype)
    box[4] = memory.read_u8(0x1E465 + wtype)

    if mainmemory.read_u8(0x450) == 1 then  -- Simon is facing left
        box[1] = box[1] * -1
        box[3] = box[3] * -1
    end
    return box
end

local function player()
    local x = mainmemory.read_u8(px)
    local y = mainmemory.read_u8(py)
    local box
    gui.drawBox(x+4,y+mainmemory.read_u8(0x5F),x-4,y-mainmemory.read_u8(0x5F),0xFF0000FF,0x400000FF)

    if mainmemory.read_u8(0x568) == 0x11 then -- Whip is active
        box = whip()
        gui.drawBox(x+box[1]+box[3],y+box[2]+box[4],x+box[1]-box[3],y+box[2]-box[4],0xFFFFFFFF,0x40FFFFFF)
    end

end

local function buildbox(i)
    local box = {0,0}  -- xrad/yrad
    local dracform = mainmemory.read_u8(0x434 + i)

    if offset == 0x1D then
        dracform = mainmemory.read_u8(0x7A)
        if dracform == 1 then
            offset = 0x30 * 2
        else
            offset = offset * 2
        end
    else
        offset = offset * 2
    end

    box = { memory.read_u8(0x1E46A + offset),memory.read_u8(0x1E46B + offset) }

    return box
end

local function getcolor(x)
    local color = {0,0} -- Fill/Outline
    if x >= 0x28 and x < 0x30 then
        color = {0x40FFA500,0xFFFFA500}
    elseif x >= 0x30 and x <= 0x35 then
        return color
    elseif x == 0x17 then -- Simon subweapon
        color = {0x4000FFFF,0xFF00FFFF}
    elseif x == 0x1D then -- dracula invuln box
        color = {0x40FF0000,0xFFFFFFFF}
    else
        color = {0x40FF0000,0xFFFF0000}
    end
    return color
end

local function objects()
    local x
    local y
    local active
    local box
    local etype
    local c
    local oob

    for i = 3,20,1 do
        oob = mainmemory.read_u8(0x300 + i)
        if oob == 0 or oob == 0x80 then
            box = buildbox(i)
            etype = mainmemory.read_u8(0x434 + i)
            c = getcolor(etype)
            x = mainmemory.read_u8(ex + i)
            y = mainmemory.read_u8(ey + i)
            gui.drawBox(x+box[1],y+box[2],x-box[1],y-box[2],c[2],c[1])
            if etype == 0x1D then -- if dracula's invuln box
                gui.drawLine(x+box[1],y,x-box[1],y,0xFFFFFFFF)
                gui.drawLine(x,y+box[2],x,y-box[2],0xFFFFFFFF)
            end
        end
    end
end


while true do
    player()
    objects()
    emu.frameadvance()
end