Super C Collision viewer

-- Author Pasky13

--Player
local px = 0x54C
local py = 0x532

--Player projectiles
local projxbase = 0x588
local projybase = 0x578

--Enemies
local ex = 0x53C
local ey = 0x522

local xm
local ym

local function draw_axis(x,y,color)
    gui.drawLine(x,y-4,x,y+4,color)
    gui.drawLine(x-4,y,x+4,y,color)
end

local function sign(val)
    if val > 0x7F then
        val = 256 + (val * -1)
    end
    return val
end

memory.usememorydomain("PRG ROM")

local function player()
    -- Player 1
    if mainmemory.read_u8(0xC6) ~= 0 then
        local x = mainmemory.read_u8(px)
        local y = mainmemory.read_u8(py)
        draw_axis(x,y,0xFF0000FF)
    end
    -- Player 2
    if mainmemory.read_u8(0xC7) ~= 0 then
        x = mainmemory.read_u8(px+1)
        y = mainmemory.read_u8(py+1)
        draw_axis(x,y,0xFF0000FF)
    end
end

local function bullets()
    -- P1
    if mainmemory.read_u8(0xC6) ~= 0 then
        for i = 0,9,1 do
            local x = mainmemory.read_u8(projxbase + i)
            local y = mainmemory.read_u8(projybase + i)

            if mainmemory.read_u8(0x638 + i) > 0 then
                gui.drawBox(x-2,y-2,x+2,y+2,0xFFFFFFFF,0x40FFFFFF)
            end
        end
    end

    -- P2
    if mainmemory.read_u8(0xC7) ~= 0 then
        for i = 0,9,1 do
            local x = mainmemory.read_u8(0x592 + i)
            local y = mainmemory.read_u8(0x582 + i)

            if mainmemory.read_u8(0x642 + i) > 0 then
                gui.drawBox(x-2,y-2,x+2,y+2,0xFFFFFFFF,0x40FFFFFF)
            end
        end
    end
end


local function enemies()
    local active
    local etype
    local fill
    local outl
    for i = 0,0x0D,1 do
        active = mainmemory.read_u8(0x508+i)  -- sprite frame
        etype = mainmemory.read_u8(0x73A + i)
        if etype == 4 or etype == 0x0C then
            fill = 0xFF00FF00
            outl = 0x3500FF00
        else
            fill = 0xFFFF0000
            outl = 0x35FF0000
        end

        local x = mainmemory.read_u8(ex + i)
        local y = mainmemory.read_u8(ey + i)

        -- Player 1 collision detection
        if mainmemory.read_u8(0xC6) ~= 0 then
            if active > 0 then
                local offset = ((mainmemory.read_u8(0xC6) + etype + 1) % 0x100)
                local xoff = sign(memory.read_u8(0x6000 + offset + 1)) + 1
                local xrad = memory.read_u8(0x6000 + offset + 3)
                local yoff = sign(memory.read_u8(0x6000 + offset)) + 1
                local yrad = memory.read_u8(0x6000 + offset + 2)
                gui.drawBox(x-xoff,y-yoff,x-xoff+xrad,y-yoff+yrad,fill,outl)

            end
        end

        -- Player 2 collision detection
        if mainmemory.read_u8(0xC7) ~= 0 then
            if active > 0 then
                local offset = ((mainmemory.read_u8(0xC7) + etype + 1) % 0x100)
                local xoff = sign(memory.read_u8(0x6000 + offset + 1)) + 1
                local xrad = memory.read_u8(0x6000 + offset + 3)
                local yoff = sign(memory.read_u8(0x6000 + offset)) + 1
                local yrad = memory.read_u8(0x6000 + offset + 2)
                gui.drawBox(x-xoff,y-yoff,x-xoff+xrad,y-yoff+yrad,fill,outl)
            end
        end

        -- Projectile collision
        if active > 0 and etype ~= 4 and etype ~= 0x0C then
            local poffset = etype + 0xA0
            local pxoff = sign(memory.read_u8(0x6000 + poffset + 1)) + 1
            local pxrad = memory.read_u8(0x6000 + poffset + 3) - 2
            local pyoff = sign(memory.read_u8(0x6000 + poffset)) + 1
            local pyrad = memory.read_u8(0x6000 + poffset + 2) - 2
            gui.drawBox(x-pxoff,y-pyoff,x-pxoff+pxrad,y-pyoff+pyrad,0xFFFFFF00,0x40FFFF00)
        end

    end
end

local function scaler()
    xm = client.screenwidth() / 256
    ym = client.screenheight() / 224
end

while true do
    scaler()
    player()
    bullets()
    enemies()
    emu.frameadvance()
end