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Using Gimp's IFS Tool

Date/Time Permalink: 04/03/10 05:56:51 pm
Category: Graphics Tutorials

Talking about Gimp's Resynthesizer tool last time got me thinking about Gimp filters again, and how so many people really don't understand how to use them and hence don't know what they're capable of. So I'm going to spotlight a few of the more intriguing ones over the next few posts. Today, Pikachu, I choose IFS, located in Filter -> Render -> Nature -> IFS.

Some general tips about using the IFS Fractal generator:

  • It takes a lot of practice. You should play with it the first few times just to get a feel for it, before you try drawing something.
  • Even though it shows the preview in foreground over background, it will not render the background color, but only the finished object on alpha transparency.
  • Dragging the little triangles around in the model view (on the left) is the worst way to handle it. A tiny tweak to something in stretch mode will turn the preview into an angry pile of sticks, and you can't figure out how to get it back. Just use the mouse for selecting the parts and moving them; leave the rest of the editing to the little spinboxes down in the bottom half of the window.
  • You can hit the 'reset' button down at the bottom at any time to restore the default Serpinski triangle formation.
  • You can also undo individual editing steps with Ctrl-Z.
  • Three things are broken in this dialog: (1) The 'rotate' button also scales when you drag with the mouse. (2) The 'stretch' button actually shears at the same time. (3) The 'select all' button doesn't do diddly. Your changes will still only affect the last selected part no matter what state the 'select all' button is in.

NOTICE: This tutorial is done with Gimp version 2.6.6!

Here's the official documentation on the Gimp IFS plug-in. It also links to some hair-graying scientific book, as if we wanted to study for our masters instead of drawing pretty pictures. Foo! Anyway, here's my example:

I start a new file, open IFS Fractal, and the first thing I do is click 'new' to add a fourth shape in the middle.

Gimp_IFS_1

Now, we want to start out with four symmetrical squares, so we use the bottom half of the dialog to set this up. We can see that shape #1 is at X=0.3, so move shape #3 to X=0.3 too. Shape #2 is at X=0.7, so let's also have #4 (the new one) at X=0.7 also. For the Y axis... here's another bug with the dialog... the crosshair is not in the middle, but rather at about Y=0.45. And by the way, did you know if you put all four shapes at Y=0.45 right now, IFS Fractal will crash and vanish? I just found that out. Anyway, have the same Y values for #1 and #2 and then a different same Y value for #3 and #4. Here I have 0.3 for the top row and 0.6 for the bottom.

Gimp_IFS_2

Shear all four shapes to -0.4. Set the four shapes' angles as follows: #1: -10.8, #2: +10.8, #3: +3.6, #4: 32.4. Scale the two shapes in the left column both to 0.46. Hey! We have something organic-looking already!

Gimp_IFS_3

We're going for a sort of pine tree branch here. However, we are not going to try to simulate the branch this way along with the foliage. We have a much better method, making it a multi-step process. Go ahead and do a color transform on shape #2 to brown if you want, though, as this will help the final product stand out. Hit 'OK'.

Now, first thing I do is select the entire shape and hit 'Ctrl-X' to cut it, 'Ctrl-V' to paste it back in, and then the rotate and scale tools to size and position it the way I want it for the time being. We're actually going to use this part like a stamp. Yes, I could have rotated and scaled the shape in the IFS Fractal dialog, but this was much easier. You can see I have also started a new layer, where we're going to do out next step.

Gimp_IFS_4

This time we're going to do the wooden branch itself, and we're going to be much more sloppy about it because we'll edit this part later. Go ahead and pick a woody brown color for the foreground, start IFS again (be careful it's in the NEW layer so we don't destroy the last shape!), and hit 'reset.' This time, since it's easier to make stick-shapes, just drag the shapes until you have something like this:

Gimp_IFS_5

I've also rotated and scaled it to taste. From here, we're going to go back and get the first shape, copy it, and paste it several times on the second shape while rotating and scaling to fit things together. Here's the structure after pasting the foliage sections on the branch.

Gimp_IFS_6

I've added a darkened pine board pattern to the background and gave it a much-needed color balance with the brightness-contrast dialog. We'll call it done there.

Gimp_IFS_branch_finished

Once again, this is intended as a quick and sloppy tutorial, just showing intermediate users what can be done. So far as I know, it's the only other Gimp IFS tutorial besides the official one. Be cool, be loose, and be gimpy!

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