spixsub

# spixsub 1.1
Function spixsub(clip c, int "left", int "top")
{
left=Default(left, 1) #set the "left" to 2 will make it 2 pass since the subtract mode in overlay ignore the negative result of subtracting, set it to -1 and will show the negative result only
top=Default(top, 0) #same as left parameter
Assert(!(left>2 || left<-1 || top>2 || top<-1), "spixsub: left and top modes must be between -1 to 2")
c
left != 0 ? PointResize(Width(), Height(), src_left=-1) : last
leftsub1 = left != 0 ? overlay(c,last,mode="Subtract") : last
leftsub2 = left == -1 || left > 1 ? overlay(last,c,mode="Subtract") : nop()
left > 1 ? overlay(leftsub1,leftsub2,mode="add") : left == -1 ? leftsub2 : leftsub1
h=last
top != 0 ? c : last
top != 0 ? PointResize(Width(), Height(), src_top=-1) : last
topsub1 = top != 0 ? overlay(c,last,mode="Subtract") : last
topsub2 = top == -1 || top > 1 ? overlay(last,c,mode="Subtract") : nop()
top > 1 ? overlay(topsub1,topsub2,mode="add") : top == -1 ? topsub2 : topsub1

top != 0 && left != 0 ? overlay(h,last,mode="add") : last
}