🚀 go-pugleaf

Perhaps you try the attached spline procedure
I've not tested it, but it looks worth a try.

%!Procedure BSpl by InterViews
/BSpl {% argument: n_pixels
0 begin
storexyn
newpath
n 1 gt {
0 0 0 0 0 0 1 1 true subspline
n 2 gt {
0 0 0 0 1 1 2 2 false subspline
1 1 n 3 sub {
/i exch def 1 sub dup i dup i 1 add dup i 2 add dup false subspline } for n 3 sub dup n 2 sub dup n 1 sub dup 2 copy false subspline
} if
n 2 sub dup n 1 sub dup 2 copy 2 copy false subspline
stroke
} if end
} dup 0 4 dict put def

/midpoint {
0 begin
/y1 exch def
/x1 exch def
/y0 exch def
/x0 exch def
x0 x1 add 2 div
y0 y1 add 2 div
end
} dup 0 4 dict put def

/thirdpoint {
0 begin
/y1 exch def
/x1 exch def
/y0 exch def
/x0 exch def
x0 2 mul x1 add 3 div
y0 2 mul y1 add 3 div
end
} dup 0 4 dict put def

/subspline {
0 begin
/movetoNeeded exch def
y exch get /y3 exch def
x exch get /x3 exch def
y exch get /y2 exch def
x exch get /x2 exch def
y exch get /y1 exch def
x exch get /x1 exch def
y exch get /y0 exch def
x exch get /x0 exch def
x1 y1 x2 y2 thirdpoint
/p1y exch def
/p1x exch def
x2 y2 x1 y1 thirdpoint
/p2y exch def
/p2x exch def
x1 y1 x0 y0 thirdpoint
p1x p1y midpoint
/p0y exch def
/p0x exch def
x2 y2 x3 y3 thirdpoint
p2x p2y midpoint
/p3y exch def
/p3x exch def
movetoNeeded { p0x p0y moveto } if
p1x p1y p2x p2y p3x p3y curveto
end
} dup 0 17 dict put def

/storexyn {
/n exch def
/y n array def
/x n array def
n 1 sub -1 0 {
/i exch def
y i 3 2 roll put
 i 3 2 roll put
} for
} def

% Example
%
% 100 100
% 150 150
% 200 125
% 250 300
% 4 BSpl
% showpage

Helge,

I find this /proc { 0 begin ... end } dup 0 4 dict put def

structure not very straightforward. Would you care to comment on it?

Miklos

Hi Helge,
Thanks for your help.
But I get an error when I try to run your proc.
The error is on the put command. I have no idea which line.
I'm a beginer at this, so I'm still trying to figure out
your procedure.
Could you check your proc and resend it to me at
coypham@yahoo.com

Thanks!

Khoi,

Sorry, there is an error caused by cut & paste, obviously. Near the end of the procedure, there are two lines

y i 3 2 roll put
 i 3 2 roll put

Please change the second line to
x i 3 2 roll put


Mikos,

I just tested the proc, and it painted a spline.
I didn't try to fully understand how it works.

Hi Helge,
I fix the second line and I remove the comment from the example like
this.

% Example
%
100 100
150 150
200 125
250 300
4 BSpl
showpage

Then I ran the procedure, but I get this error message log.

%%[ Error: stackunderflow; OffendingCommand: sub ]%%
Stack:
1
%%[ Flushing: rest of job (to end-of-file) will be ignored ]%%
%%[ Warning: PostScript error. No PDF file produced. ] %%

Can you help?

Thanks,
Khoi