Image sequence breaks in gif animation - php

Question

I am trying to animate all images in a directory with imagemagick's morph operator. I am calling the command-line arguments with PHP's exec command. The images hold a specific file name such as 000000.jpg, 000001.jpg, 000002.jpg, 000003.jpg, and so on.
the following code works fine from image sequence 000000.jpg to 000009.jpg, but when I have images such as 0000010.jpg, the 0000010.jpg comes after 000001.jpg while I want 000002.jpg should come after 000001.jpg. Can you please point out how to modify the code so that I can retain a sequence in gif animation?
$command = "convert -set delay 5 -loop 0 $img_dir/00000*.jpg -morph 10 $img_dir/morph.gif";
exec($command);

Answer 1

Normally, the length of the name is kept constant, so if you add an extra digit in going from 9 to 10, you remove one of the leading zeroes to keep the length the same. I mean, most people do this:
000008
000009
000010
000011
whereas you appear to have done this where the length changes at 10:
000008
000009
0000010
0000011
I would suggest you change the program that generates the naming so it generates a constant length name then everything will work properly.
Failing that, if you wish to, or are obliged to, stick with your naming system, ImageMagick will accept a list of files in any order you like, so you can create a file called filelist.txt or somesuch, with contents like this
000000.jpg
000001.jpg
000002.jpg
...
000009.jpg
0000010.jpg
0000011.jpg
and use it like this:
convert -delay 100 -loop 0 #filelist.txt anim.gif
Alternatively, you could let bash print your filenames always with 5 leading spaces using a command such as this:
printf "00000%d.jpg " {0..4}
000000.jpg 000001.jpg 000002.jpg 000003.jpg 000004.jpg
and embed that in your ImageMagick command
convert -delay 100 -loop 0 $(printf "00000%d.jpg " {0..4}) anim.gif