-- circle map function
function circmap(x,y,r)
    for y2=-r,r do
        x2=sqrt(abs(y2*y2-r*r))
        tline(x-x2,y+y2,x+x2,y+y2,(x-x2)/8,(y+y2)/8)
    end
end

-- function to darken the palette
function dark(l)
    l=l or 0
    if l>0 then
        for i=0,15 do
            col=dpal[i] or 0
            for a=1,l-0.5 do
                col=dpal[col]
            end
            pal(i,col)
        end
    end
end

function _init()

    -- dark palette
    dpal={0,1,1,2,1,13,6,2,4,9,3,13,5,2,9}

    t=0
    x=64
    y=64
    r=32
end

function _update()

    -- circle position and size
    x=64+sin(t/100)*32
    y=64+cos(t/100)*32
    r=32+sin(t/50)*16

    -- timer and loop
    t+=1

end

function _draw()

    cls()

    -- darkens the palette 2 times
    dark(2)

    -- draws map
    map()

    -- resets palette
    pal()

    -- draws circmap
    circmap(x,y,r)

end

-- circle map function
function circmap(x,y,r)
    for y2=-r,r do
        x2=sqrt(abs(y2*y2-r*r))
        tline(x-x2,y+y2,x+x2,y+y2,(x-x2)/8,(y+y2)/8)
    end
end

-- function to darken the palette
function dark(l)
    l=l or 0
    if l>0 then
        for i=0,15 do
            col=dpal[i] or 0
            for a=1,l-0.5 do
                col=dpal[col]
            end
            pal(i,col)
        end
    end
end

function _init()

    -- dark palette
    dpal={0,1,1,2,1,13,6,2,4,9,3,13,5,2,9}

    t=0
    x=64
    y=64
    r=32
end

function _update()

    -- circle position and size
    x=64+sin(t/100)*32
    y=64+cos(t/100)*32
    r=32+sin(t/50)*16

    -- timer and loop
    t+=1

end

function _draw()

    cls()

    -- darkens the palette 2 times
    dark(2)

    -- draws map
    map()

    -- resets palette
    pal()

    -- draws circmap
    circmap(x,y,r)

end