Introduction

This new deformation tool for Gimp tries to provide an new approach for deforming a part of an image. The goal is to have a more flexible and intuitive way to deform an element, with a respect of the shape of this element. It works best on already extracted elements as the transformation is only applied to the inside of the cage.

Details

This tool allows deforming an element or an image by using a cage. Cage is a closed polygon that can have more than 4 edges. The basic way to use it is:

Select the cage tool in the toolbox
Click on the image to draw a cage (surround your element with the cage)
Close the cage with a click on the first handle
The tool computes internal data, and draws a preview
Move the handles to deform your element
When you are good with the deformation, hit the enter key
The tool compute the final render and commits the change

Options

For now, the only option provided, is the choice to optionally fill the original position of the cage with the color under the first vertex of the cage (see screen-shot).

Screenshot

Internals

This tool uses the Green Coordinates, as described in the following publication, by Yaron Lipman, David Levin and Daniel Cohen-Or.

http://www.math.tau.ac.il/~lipmanya/GC/gc_techrep.pdf (Siggraph 2008)

This tool is implemented in the backend as a Gegl operation, with GIMP handling the presentation/UI.

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