This tutorial shows how to set up Paint Dynamics to make tapered lines.
Important note: This tutorial works only in the Git master
development version of GIMP 2.7. It will not work in GIMP 2.6.
Tapered lines work as of March 2010.
I will update this if the UI changes.
Bring up the Paint Dynamics window with Windows->Dockable dialogs->Paint dynamics.
Make a new dynamic by clicking on the New button. Give it some sort of helpful name like Tapered lines. You'll get an editing window showing a matrix of options.
Under Mapping matrix in the Dynamics editor,
Size should vary with Fade and nothing else should be checked.
Then back in Tool Options, turn on Fade out and Reverse.
Now draw in the image window -- you should have a taper!
You can adjust the length of the taper with Fade out Length
in Tool Options. You may also want to adjust the Spacing of the brush,
in the Brushes dialog.
You can even do double-tapered lines. For that, choose the Size
menu in the dynamics editor and drag the upper right point of the
curve down to the bottom. Then drag the middle up so your curve looks
like an inverse U. You may want to go back to Tool Options and
turn off Reverse.
And voilà -- lovely smooth double-tapered lines! It doesn't
work every time -- sometimes you get odd glitches. But remember, this
is just the development version, and this code is very young yet.
It's pretty awesome already!