(Line)APX_screenchange
{exch pop}

(Rhomboid)APX_screenchange
{abs exch abs .9 mul add 2 div}

(Diamond)APX_screenchange
{abs exch abs 2 copy add .75 le{dup mul exch dup mul add 1 exch sub}{2 copy add 1.25 le{.85 mul add 1 exch sub}{1 sub dup mul exch 1 sub dup mul add 1 sub}ifelse}ifelse}

(-) 3{pop}repeat

(Euclidean)APX_screenchange
{abs exch abs 2 copy add 1 gt{1 sub dup mul exch 1 sub dup mul add 1 sub}{dup mul exch dup mul add 1 exch sub}ifelse}

(Elliptical Inverse)APX_screenchange
{dup mul .9 mul exch dup mul add 1 sub}

(Elliptical)APX_screenchange
{dup mul .9 mul exch dup mul add 1 exch sub}

(Double Inverse)APX_screenchange
exch 2 div exch{2{360 mul sin 2 div exch}repeat add neg}

(Double)APX_screenchange
exch 2 div exch{2{360 mul sin 2 div exch}repeat add}

(Round Inverse)APX_screenchange
{dup mul exch dup mul add 1 sub}

(Round)APX_screenchange
{dup mul exch dup mul add 1 exch sub}

(-) 3{pop}repeat

(Default)APX_screenchange
currentscreen 3 1 roll pop pop dup type/dicttype eq{/SpotFunction get}if