🚀 go-pugleaf

  I'm not exactly a PS wizard, but I'll take a stab at this. The 'concat'
operator modifies the current coordinate system. It's a generalization
of translate, scale, and rotate... basically, it takes a 6-element array,
[a b c d e f], converts it into the matrix

[a  c  0]
[b  d  0]
[e  f  1]

  (I may have the upper left corner transposed). Anyway, it then replaces
the current coordinate transformation matrix (which is what specifies
the correspondence between 'points' and device pixels) withe the old
CTM multiplied by this matrix. For instance,

[1 0 0 1 15 37] concat

 has the same effect as

15 37 translate

  ... I think. (In effect, adding 15 to every X coordinate and 37 to every Y
coordinate given from then on.) I'm not sure why a paint program would be 
changing its coordinate system before every line it draws, but who can
fathom machine-generated code?

-- 
 wiml@milton.acs.washington.edu       Seattle, Washington   
     (William Lewis)   |  47 41' 15" N   122 42' 58" W  
"These 2 cents will cost the net thousands upon thousands of 
dollars to send everywhere. Are you sure you want to do this?"